- The first synthesis of tonkinecin, an annonaceous acetogenin with a C-5 carbinol center
-
(formula presented) Reported herein is the first synthetic approach to tonkinecin (1) which uses a palladium-catalyzed cross-coupling reaction between the tetrahydrofuran unit (4) and the butenolide (3) as the key step for constructing the backbone of 1. The stereogenic centers at C-5, C-21, C-22, and C-36 were derived from D-xylose, D-glucose, and L-lactate, respectively, whereas those at C-17, and C-18 were generated using Sharpless asymmetric dihydroxylation.
- Hu, Tai-Shan,Yu, Qian,Lin, Qi,Wu, Yu-Lin,Wu, Yikang
-
-
Read Online
- An expeditious synthesis of alk-2-yn-1-ols
-
A convenient inexpensive preparation of alk-2-yn-1-ols, commencing from terminal alkynes, has been developed. This procedure allows for using paraformaldehyde instead of gaseous formaldehyde for hydroxymethylation of alk-1-ynylmagnesium bromides.
- Zwierzak, Andrzej,Tomassy, Beata
-
-
Read Online
- Synthesis of medium- and large-sized lactones in an aqueous-organic biphasic system
-
(Chemical Equation Presented) Saving solvent: An aqueous-ethyl acetate biphasic system allows an efficient synthesis of medium- and large-sized lactones by an intramolecular Tsuji-Trost reaction (see scheme, n = 1-5). The macrocyclization protocol does not require a large quantity of solvents or a slow-addition technique.
- Kinoshita, Hidenori,Shinokubo, Hiroshi,Oshima, Koichiro
-
-
Read Online
- A simple, convenient, general procedure for the synthesis of 2-alkyn-1-ylboronates.
-
Representative 2-alkyn-1-ylboronates have been synthesized in good to excellent yields using the reaction of the newly available diisopropyl iodomethylboronate with alkynyllithiums generated in situ. Comparable yields are obtained from both acyclic and cyclic boronates. However, 2-(iodomethyl)-1,3,2-dioxa-4,4,5-tetramethylborolane gave superior yields with a wide variety of alkynyllithiums. This procedure offers a simple and convenient alternative route to existing methodologies in terms of the milder reaction condition and the ease of the operation.
- Brown, Herbert C.,Roy, Chandra Deo,Soundararajan, Raman
-
-
Read Online
- Gold(I)-Catalyzed Angle Strain Controlled Strategy to Furopyran Derivatives from Propargyl Vinyl Ethers: Insight into the Regioselectivity of Cycloisomerization
-
A unique strategy for the regiospecific synthesis of bicyclic furopyran derivatives has been developed via a gold(I)-catalyzed propargyl-Claisen rearrangement/6-endo-trig cyclization of propargyl vinyl ethers. The introduction of angle strain into the substrates significantly altered the reaction's regioselectivity. Insight into the regioselectivity of the cycloisomerization was obtained with density functional theory calculations. (Chemical Equation).
- Jin, Shengfei,Jiang, Chongguo,Peng, Xiaoshi,Shan, Chunhui,Cui, Shanshan,Niu, Yuanyuan,Liu, Yang,Lan, Yu,Liu, Yongxiang,Cheng, Maosheng
-
-
Read Online
- Preparation and cancer cell invasion inhibitory effects of C16-alkynic fatty acids.
-
Five C(16)-alkynic fatty acids (2-6) were prepared and examined their inhibitory effects on cancer cell invasion. It has been found that hexadeca-6,8,10-triynoic acid (5) and hexadeca-8,10,12-triynoic acid (6) exhibit similar potent inhibitory activities with that of octadeca-8,10,12-triynoic acid (1) which was isolated from Scurrula atropurpurea (Loranthaceae).
- Ohashi, Kazuyoshi,Winarno, Hendig,Mukai, Mutsuko,Shibuya, Hirotaka
-
-
Read Online
- Enantioselective Rhodium-Catalyzed Dimerization of ω-Allenyl Carboxylic Acids: Straightforward Synthesis of C2-Symmetric Macrodiolides
-
Herein, we report on the first enantioselective and atom-efficient catalytic one-step dimerization method to selectively transform ω-allenyl carboxylic acids into C2-symmetric 14- to 28-membered bismacrolactones (macrodiolides). This convenient asymmetric access serves as an attractive route towards multiple naturally occuring homodimeric macrocyclic scaffolds and demonstrates excellent efficiency to construct the complex, symmetric core structures. By utilizing a rhodium catalyst with a modified chiral cyclopentylidene-diop ligand, the desired diolides were obtained in good to high yields, high diastereoselectivity, and excellent enantioselectivity.
- Steib, Philip,Breit, Bernhard
-
-
Read Online
- Facile synthesis of substituted 3-aminofurans through a tandem reaction of N-sulfonyl-1,2,3-triazoles with propargyl alcohols
-
A relay catalysis strategy for substituted 3-aminofurans synthesis has been developed. This transformation involves a tandem reaction sequence through aza-vinyl-rhodium(ii) carbene O-H bond insertion, thermal propargyl-Claisen rearrangement and gold(i)-catalyzed intramolecular cyclization. More importantly, the current strategy employs simple feedstocks as starting materials, providing substituted 3-aminofurans in a highly efficient manner.
- Cheng, Xing,Yu, Yinghua,Mao, Zhifeng,Chen, Jianxin,Huang, Xueliang
-
-
Read Online
- Synthesis of polyacetylenic acids isolated from Heisteria acuminata
-
matrix presented Four linear polyacetylenic compounds were synthesized. Pentadeca-6,8,10-triynoic acid 1 and octadeca-8,10,12-triynoic acid 2 were synthesized by using acetylene coupling reactions. The syntheses of (Z)-hexadec-11-en-7,9-diynoic acid 3 and (Z)-octadec-12-en-7,9-diynoic acid 4 by using vinylic telluride coupling reactions were accomplished.
- Zeni, Gilson,Panatieri, Rodrigo B.,Lissner, Eliseo,Menezes, Paulo H.,Braga, Antonio L.,Stefani, Helio A.
-
-
Read Online
- A Convenient One-Pot Method for the Hydroxymethylation of Grignard Reagents
-
Grignard reagents and alkynyllithiums can be hydroxymethylated in a two-step one-pot reaction by reaction of a Grignard reagent with 1-chloro-2-(chloromethoxy)ethane (1), followed by treatment with sodium-potassium alloy and aqueous workup.The reaction was found to work for primary, secondary, tertiary, benzylic, allylic and aryl Grignard reagents in yields ranging from 57 - 95 percent.
- Ogle, C. A.,Wilson, T. E.,Stowe, J. A.
-
-
Read Online
- A facile, catalytic, and environmentally benign method for selective deprotection of teri-butyldimethylsilyl ether mediated by phosphomolybdic acid supported on silica gel
-
An environmentally benign PMA supported on SiO2 is found to be an efficient catalyst for the chemoselective deprotection of TBDMS ethers under very mild conditions. Various labile functional groups such as isopropylidene acetal, OTBDPS, OTHP, Oallyl, OBn, alkene, alkyne, OAc, OBz, N-Boc, N-Cbz, N-Fmoc, mesylate, and azide are found to be stable under the reaction conditions. This "truly catalytic" heterogeneous reaction does not require aqueous workup, and the supported catalyst and the solvent can be readily recovered and recycled.
- Kishore Kumar,Baskaran, Sundarababu
-
-
Read Online
- An efficient synthesis of (-)-pestalotin and its enantiomer using Sharpless asymmetric dihydroxylation
-
With Sharpless asymmetric dihydroxylation as a key step, syntheses of (-)-pestalotin and its enantiomer have been accomplished in a four-step sequence in high stereoselectivity.
- Wang, Zhi-Min,Shen, Ming
-
-
Read Online
- An improved synthesis route to functionalized 2-alkyn-1-ylboronates: Useful intermediates for the preparation of α-allenic alcohols
-
Functionalized 2-alkyn-1-ylboronates were successfully prepared in good yields by reacting various acyclic and cyclic (iodomethyl)boronates with various alkynyllithium salts. Amongst various (iodomethyl)boronates studied, 2-(iodomethyl)-1,3,2-dioxa-4,4,5,5-tetramethylborolane provided improved chemical yields of 2-alkyn-1-ylboronates with pyran- and triisopropylsilyl- substituted alkynyllithium salts. 2-Alkyn-1-ylboronate bearing an acid sensitive structure (pyran) was successfully synthesized which would be very difficult to achieve under previously reported reaction conditions. The exceptionally rapid rearrangement of the "ate" complex derived from the pinacol (iodomethyl)boronate, suppression of the side product formation, and the stability of the pinacol 2-alkyn-1-ylboronate are some of the notable merits of this protocol. This new procedure offers a simple and convenient alternative route to the existing methodologies, in terms of the milder reaction conditions, functional group compatibility, and the ease of the operation. The synthesis scope of this class of 2-alkyn-1-ylboronates was demonstrated by reacting the pinacol 2-alkyn-1-ylboronate with benzaldehyde, which yielded the α-allenic alcohol in good yield and regioselectivity.
- Roy, Chandra D.,Soundararajan, Raman,Brown, Herbert C.
-
-
Read Online
- Metal-Free Catalyzed Cyclization of N-Methoxybenzamides to Construct Quaternary Carbon-Containing Isoindolinones
-
Through the intramolecular cyclization of N-methoxybenzamides, a simple and efficient method for constructing valuable isoindolinones under metal-free conditions was developed. The reaction was featured by employing low-cost catalyst, simple operation, 100% atomic economy and excellent regioselectivity. Moreover, a detailed computational study on the reaction system has been performed to clarify the mechanism. This protocol tolerated a variety of functional groups and provided a metal-free protocol for the synthesis of chromane- or tetrahydroquinoline-fused isoindolinones in good yields.
- Zhang, Lin-Bao,Wang, Zi-Chen,Sun, Sheng-Zheng,Ni, Shao-Fei,Wen, Li-Rong,Li, Ming
-
supporting information
p. 903 - 908
(2021/04/09)
-
- Synthesis of (5Z,7E)-dodecane-5,7-diene-1-alcohol as well as acetate and propionate thereof
-
The invention belongs to the technical field of insect pheromone synthesis, and discloses a new method for synthesizing (5Z,7E)-dodecane-5,7-diene-1-alcohol as well as acetate and propionate thereof.The method takes propynol as an initial raw material to be subjected to coupling with 1-bromobutane to generate 2-heptyne-1-alcohol, triple bond is reduced to be E-type double bond through LiAlH4, 2-heptyne-1-alcohol is oxidized to be olefine aldehyde through PDC, olefine aldehyde reacts with a Wittig reagent (5-ethyoxyl-5-oxopentyl)triphenyl phosphonium bromide to produce (5Z,7E)-dodecane-5,7-dienoic acid ethyl ester which is reduced by LiAlH4 to obtain (5Z,7E)-dodecane-5,7-diene-1-alcohol, (5Z,7E)-dodecane-5,7-diene-1-alcohol reacts with acetyl chloride and propionyl chloride finally to obtain (5Z,7E)-dodecane-5,7-diene-1-alcohol acetate and (5Z,7E)-dodecane-5,7-diene-1-alcohol propionate. The method utilizes LiAlH4 to reduce the triple bond to be the E-type double bond, and utilizes theWittig reaction of the Wittig reagent with the tail end provided with ester group and aldehyde to directly build the Z-type double bond, the synthesis route is simple, convenient and efficient, and the reaction condition is moderate and environmentally friendly.
- -
-
Paragraph 0026-0028
(2019/03/28)
-
- Catalytic Generation of Rhodium Silylenoid for Alkene-Alkyne-Silylene [2 + 2 + 1] Cycloaddition
-
An alkene-alkyne-silylene [2 + 2 + 1] cycloaddition takes place in the rhodium-catalyzed reaction of 1,6-enynes with borylsilanes bearing an alkoxy group on the silicon atoms, which react as synthetic equivalents of silylene. The reaction proceeds efficiently in 1,2-dichloroethane at 80-110 °C in the presence of a rhodium catalyst bearing bis(diphenylphosphino)methane (DPPM) as a ligand to afford 1-silacyclopent-2-enes in good to high yields.
- Ohmura, Toshimichi,Sasaki, Ikuo,Suginome, Michinori
-
supporting information
p. 1649 - 1653
(2019/03/20)
-
- Direct Access to Allenylphosphine Oxides via a Metal Free Coupling of Propargylic Substrates with P(O)H Compounds
-
A direct and convenient approach for the coupling of propargylic substrates with diphenylphosphine oxide in the presence of Tf2O and 2,6-lutidine has been developed. The method provides a general approach for the construction of attractive allenylphosphoryl skeletons with high atom and step economy under metal free conditions.
- Yang, Chun-Hua,Fan, Huihui,Li, Huimin,Hou, Shenyin,Sun, Xiangkun,Luo, Donghao,Zhang, Yinchao,Yang, Zhantao,Chang, Junbiao
-
supporting information
p. 9438 - 9441
(2019/11/20)
-
- Rhodium-catalyzed asymmetric synthesis of β-branched esters from allylic amines
-
Allylic amines are converted to chiral, β-branched esters under rhodium catalysis in the presence of alcohol nucleophiles. Allylic amines with aliphatic and aromatic vinylic substituents are converted to ester products with excellent enantioselectivities in all cases. Several alcohol nucleophiles have been utilized in the reaction including 1° and 2° derivatives.
- Laffoon, Summer D.,Wu, Zhao,Hull, Kami L.
-
supporting information
p. 7814 - 7817
(2018/07/25)
-
- Stereoselective Alkyne Hydrohalogenation by Trapping of Transfer Hydrogenation Intermediates
-
A catalytically generated vinylcopper complex, the reactive intermediate of a copper(I)-catalyzed alkyne transfer hydrogenation, can be trapped by commercially available halogen electrophiles. In this manner, internal alkynes can stereoselectively be hydrohalogenated to the corresponding vinyl chlorides, bromides, and iodides.
- Das, Manas,Kaicharla, Trinadh,Teichert, Johannes F.
-
supporting information
p. 4926 - 4929
(2018/08/24)
-
- Benzannulation of triynes to generate functionalized arenes by spontaneous incorporation of nucleophiles
-
The thermal reaction of ester-tethered 1,3,8-triynes provides novel benzannulation products with concomitant incorporation of a nucleophile. Evidence suggests that this reaction proceeds via an allene-enyne intermediate generated by an Alder-ene reaction in the first step. Depending on the substituent of the alkyne moiety on the allene-enyne intermediate, the subsequent transformation can take one of two different paths, each leading to discrete aromatization products. The benzannulation of a silane-substituted 1,3,8-triynes provides arene products with a nucleophile incorporated onto the newly formed benzene core, whereas an aryl substituent leads to nucleophile trapping at the benzylic carbon atom connected to the aryl substituent. The formation of these two different products results from the involvement of two regioisomeric allene-enyne intermediates.
- Karmakar, Rajdip,Yun, Sang Young,Chen, Jiajia,Xia, Yuanzhi,Lee, Daesung
-
supporting information
p. 6582 - 6586
(2015/06/02)
-
- First stereoselective total synthesis of pectinolide C and total synthesis of pectinolide A
-
The first stereoselective synthesis of pectinolide C and synthesis of pectinolide A, from easily accessible 1-hexyne and d-mannitol are reported in a convergent manner. The salient features include acetylenic addition to the chiral aldehyde and Still-Genn
- Sabitha, Gowravaram,Das, Sukant Kishore,Ankireddy, Praveen,Yadav
-
p. 1097 - 1099
(2013/04/23)
-
- Silver(I)-Catalyzed deprotection of p -methoxybenzyl ethers: A mild and chemoselective method
-
The p-methoxybenzyl protecting group (PMB) on various alcohols and an acid was efficiently and selectively cleaved by the action of a catalytic amount of silver(I) hexafluoroantimonate combined with 0.5 equiv of 1,3,5- trimethoxybenzene in dichloromethane at 40 °C.
- Kern, Nicolas,Dombray, Thomas,Blanc, Aurelien,Weibel, Jean-Marc,Pale, Patrick
-
p. 9227 - 9235,9
(2012/12/12)
-
- Copper-catalyzed enantioselective allylic substitution with alkylboranes
-
The first catalytic enantioselective allylic substitution reaction with alkylboron compounds has been achieved. The reaction between alkyl-9-BBN reagents and primary allylic chlorides proceeded with excellent γ-selectivities and high enantioselectivities under catalysis of a Cu(I)-DTBM-SEGPHOS system. The protocol produces terminal alkenes with an allylic stereogenic center branched with functionalized sp3-alkyl groups. The reaction with a γ-silicon-substituted allyl chloride affords an efficient strategy for the enantioselective synthesis of functionalized α-stereogenic chiral allylsilanes.
- Shido, Yoshinori,Yoshida, Mika,Tanabe, Masahito,Ohmiya, Hirohisa,Sawamura, Masaya
-
supporting information
p. 18573 - 18576
(2013/01/15)
-
- First stereoselective total synthesis of gallicynoic acids G and H
-
A stereoselective convergent total synthesis of two acetylenic acids, gallicynoic acid G (1) and H (2), is reported, involving asymmetric reduction of alkynones 3 and 4, respectively, with the Corey- Bakshi-Sibata (CBS) catalyst as a key step (Scheme 3), 3 and 4 being obtained from a common intermediate, the chiral alkynol 12 (Scheme 2). Copyright
- Radha Krishna, Palakodety,Anitha, Kadimi
-
experimental part
p. 1246 - 1253
(2011/09/14)
-
- Regioselective radical bromoallylation of allenes leading to 2-bromo-substituted 1,5-dienes
-
The regioselective radical bromoallylation of allenes proceeded efficiently in the presence of AIBN as a radical initiator to give 2-bromo-substituted 1,5-dienes in excellent yields. The addition of a bromine radical took place regioselectively onto the central carbon of allenes generating a stable allyl radical, which underwent addition/β-fragmentation reactions with allylbromides. The products could be further functionalized by Pd-catalyzed coupling reactions.
- Kippo, Takashi,Fukuyama, Takahide,Ryu, Ilhyong
-
supporting information; experimental part
p. 3864 - 3867
(2011/09/15)
-
- Polyunsaturated alkyl amides from echinacea: Synthesis of diynes, enynes, and dienes
-
The synthesis of 20 alkyl amides, including 15 naturally occurring polyunsaturated alkyl amides previously identified from Echinacea spp. (1-13 and 62) or from Achilla sp. (55) and five previously unknown geometric isomers (23, 28, 67, 73, and 80), is described. Importantly, these amides include all of the major alkyl amides present in commercially used Echinacea extracts. The syntheses demonstrate methodology used for constructing alkyl amides containing conjugated diyne and isomerically pure enyne and diene moieties and may be adapted easily for the preparation of other alkyl amides present in Echinacea spp. Terminal-conjugated diynes were prepared by a Cadiot-Chodkiewitz coupling/deprotection sequence utilizing a protected bromoacetylene, and methyl-substituted diynes were made via a base-catalyzed rearrangement of terminal-skipped diynes. Conjugated dienes were prepared conveniently and with high stereoselectivity by the reduction of enynes or diynes with Rieke zinc. With the exception of 1-2 and 11-12, the alkyl amides are synthesized here for the first time, and their NMR data are consistent with that of the reported isolated natural compounds.
- Matovic, Nicholas J.,Hayes, Patricia Y.,Penman, Kerry,Lehmann, Reginald P.,De Voss, James J.
-
scheme or table
p. 4467 - 4481
(2011/07/30)
-
- Enantioselective synthesis of Anomala osakana pheromone and Janus integer pheromone: A flexible approach to chiral γ-butyrolactones
-
The enantioselective synthesis of Anomala osakana pheromone and Janus integer pheromone has been achieved without using any protecting groups. The synthesis involved using an asymmetric alkynylation to obtain γ-hydroxy-α,β-acetylenic esters with high ee (84%) and yields (~80%), followed by selective hydrogenation and lactonization in high overall yields (87% and 89%).
- Lin, Li,Zhao, Qiangyang,Li, A-Ni,Ren, Fengbo,Yang, Fanzhi,Wang, Rui
-
supporting information; experimental part
p. 3663 - 3665
(2009/10/23)
-
- Asymmetric synthesis of α-allenylglycines
-
The coupling of the homocuprate of the bislactim ether of cyclo-(-L-Val-Gly-) (9) with primary propargyl halides produces the allenyl-substituted bislactim ethers 11 in a highly diastereoselective manner, whereas the alkylation of the lith-iated bislactim ether of cyclo-(-L-Val-Gly-) yields the proparg-yl-substituted bislactim ethers 12. Subsequent hydrolysis affords, after protection of the amino group, the methyl α- allenylglycinates 15, the α-allenylglycines 16, and the methyl α-propargylglycinates 17.
- Bucuroaia, Carmen,Groth, Ulrich,Huhn, Thomas,Klinge, Michael
-
experimental part
p. 3605 - 3612
(2009/12/01)
-
- A facile and regioselective synthesis of 2,5-disubstituted pyrroles via gold-catalyzed cycloisomerization of acetylenylaziridines
-
Gold-catalyzed cycloisomerization reaction of acetylenylaziridines provides 2,5-disubstituted pyrroles in high yields. The presence of protic species accelerates the reaction rate and improves the yields of pyrrole products.
- Chen, Dong-Dong,Hou, Xue-Long,Dai, Li-Xin
-
supporting information; experimental part
p. 6944 - 6946
(2010/02/27)
-
- De novo formal synthesis of (-)-apicularen A via an iterative asymmetric hydration sequence
-
(Chemical Equation Presented) A de novo approach to the formal total synthesis of the macrolide natural product (-)-apicularen A has been achieved in 18 steps'from achiral starting materials. Both the absolute and relative stereochemistries of apicularen A were introduced by a Sharpless asymmetric dihydroxylation, a π-allyl-palladium catalyzed reduction, a stereoselective reduction, and a base-promoted transannulation to install the C-9 stereocenter.
- Li, Miaosheng,O'Doherty, George A.
-
p. 6087 - 6090
(2007/10/03)
-
- Epoxycarboxamide compound, azide compound, and amino alcohol compound, and process for preparing alpha-keto amide compound using them
-
The present invention is to provide manufacturing intermediates which can be led to useful α-ketoamide compounds having protease-inhibiting activity extremely economically and stereoselectively, and to provide epoxycarboxamide compounds, azide compounds and amino alcohol compounds represented by the following formulae: wherein R1 and R2 each represents alkyl group, alkenyl group, aromatic hydrocarbon group or heterocyclic group; R3 represents alkyl group, alkenyl group, aromatic hydrocarbon group, heterocyclic group, R6—O— or R7—N(R8)—; where R6 represents alkyl group, alkenyl group, aromatic hydrocarbon group or heterocyclic group; R7 and R8 each represents hydrogen atom, alkyl group, alkenyl group, aromatic hydrocarbon group or heterocyclic group, and, R4 and R5 represent the same groups as R7 and R8, respectively, and R4 and R5 optionally form a ring together; and X represents —O— or —N(R9)—, where R9 represents hydrogen atom or alkyl group, and X optionally forms a ring together with R4 or R5, and processes for preparing α-keto amide compound using the same.
- -
-
-
- Synthesis of (15S,16S,21R)-4-deoxyrollicosin analog
-
Synthesis of 4-deoxy rollicosin analog 2 was completed in nine steps, which was based on palladium-catalyzed coupling of two building blocks 3 and 4. Lactone 3 was synthesized from 5-hexyn-1-ol, and vinyl iodide 4 was accessed from L-glutamate and 1-hexyne.
- Lee, Jeng-Lin,Lin, Chi-Fong,Hsieh, Ling-Yu,Lin, Wan-Ru,Chiu, Huey-Fen,Wu, Yang-Chang,Wang, Kun-Sheng,Wu, Ming-Jung
-
p. 7833 - 7835
(2007/10/03)
-
- Electrotelluration: A new approach to tri- and tetrasubstituted alkenes
-
A novel electrotelluration process is described in which a Michael addition of an alkyl or aryl tellurolate anion occurs onto an activated alkyne with subsequent trapping of a vinyl anion with electrophiles (aldehydes and ketones) other than a proton. This process provides an efficient regio-and stereospecific route to tri- and tetrasubstituted alkenes. Methodologically significant examples of this chemistry were studied in which aryl and alkyl tellurolate anions were added to ω-keto alkynyl esters in a Michael reaction, and the incipient vinyl anions were trapped intramolecularly by the internal aldehydes. The reactive centers were tethered by different lengths of alkyl chains to form highly functionalized five-, six-, seven-, and eight-membered rings in modest to good yields.
- Marino, Joseph P.,Nguyen, Hanh Nho
-
p. 6291 - 6296
(2007/10/03)
-
- Enzyme-triggered enantioconvergent transformation of haloalkyl epoxides
-
Biocatalytic hydrolysis of 2,3-disubstituted rac-cis- and rac-trans-haloalkyl epoxides 1a-8a using the epoxide hydrolase activity of whole bacterial cells furnished the corresponding vicinal diols 1b-8b as intermediates; these (spontaneously) underwent ring closure to yield cyclic products 1c-6c through an enzyme-triggered cascade reaction. In particular, cis-configured substrates (1a, 3a, 5a, 7a) were transformed in an enantioconvergent fashion, which resulted in the formation of single stereoisomeric products in 100% des and up to 92% ees from the racemates.
- Mayer, Sandra F.,Steinreiber, Andreas,Orru, Romano V. A.,Faber, Kurt
-
p. 4537 - 4542
(2007/10/03)
-
- An enzyme-triggered enantio-convergent cascade-reaction
-
The biocatalytic hydrolysis of the (±)-2,3-disubstituted cis-chloroalkyl epoxides 1a and 2a using resting cells of Rhodococcus sp. did not give the corresponding chloroalkyl vic-diols 1b, and 2b, respectively, but furnished the rearranged products (2R,3R)-1c and (2R,3R)-2c in high e.e. as the sole products via an enzyme-triggered enantio-convergent cascade-reaction.
- Mayer, Sandra F.,Steinreiber, Andreas,Orru, Romano V.A.,Faber, Kurt
-
-
- Chromium(II)-Mediated Stereodivergent Additions of Allylic Phosphates and Halides to Aldehydes
-
The addition of γ-disubstituted allylchromium(III) reagents to aldehydes proceeds in a stereodivergent manner, in contrast to the case of γ-monosubstituted allylchromium(III) species.The method allows the preparation of a variety of homoallylic alcohols bearing a quaternary center of defined relative configuration in the α-position.The preparation of both stereomeric homoallylic alcohols 13 is possible by using either of the two (E)- or (Z)-allylic precursors.The reaction has been extended to a γ-monosubstituted β-(trimethylsilyl)allylic system.The intermediate allylic chromium(III) reagents can be conveniently prepared from the corresponding phosphates (or chlorides) in DMPU or THF in the presence of catalytic amounts of LiI.
- Nowotny, Stefan,Tucker, Charles E.,Jubert, Carole,Knochel, Paul
-
p. 2762 - 2772
(2007/10/02)
-
- Preparation of Polyfunctional Allenic Alcohols by the Regioselective Addition of Functionalized Propargylic Chromium(III) Organometallics to Carbonyl Compounds
-
The reaction of propargylic halides 1 (X = Cl, Br) with an aldehyde or ketone (0.67 equiv) in the presence of CrCl2 (2.0 equiv) and LiI (2 equiv, necessary if X = Cl) affords allenic alcohols 3 with excellent regioselectivities (3-6percent of the regioiso
- Belyk, Kevin,Rozema, Michael J.,Knochel, Paul
-
p. 4070 - 4074
(2007/10/02)
-
- Synthesis of lysophosphatidylserine with 19:4 acyl group, as a novel sodium-potassium ATPase inhibitor, in relation to DLIS-2, an endogenous digoxin-like substance
-
A lysophosphatidylserine with 19:4 acyl group proposed as a candidat of DLIS-2, an endogenous digoxin-like substance was chemically synthesized. The synthetic compound showed a significant activity of Na+,K+-ATPase inhibition, which has been accepted as a major indicator activity for the essential hypertension.
- Inami,Teshima,Emura,Shiba
-
p. 4033 - 4036
(2007/10/02)
-
- 2,5,6,7-tetranor-18,18,19,19-tetradehydro-4,8-inter-m-phenylene PGI2 derivatives
-
Disclosed herein are novel prostaglandin I2 (PGI2) derivatives exhibiting excellent physiological activities, said derivatives being represented by the general formula: STR1 wherein R1, R2 and R3 are as defined herein.
- -
-
-
- REACTIONS OF ?-ALLYL COMPLEXES OF Ti(III) WITH ALLYL, ALKYL, AND PROPARGYL ELECTROPHILES
-
The reactions of the ?-allyl complexes of Ti(III) with allyl bromides lead to the production of a mixture of cross-coupling and homocoupling products.In the case of alkyl and propargyl halides the dehalogenation products are formed.The reaction of the ?-allyl complexes of Ti(III) with allyl acetates, allyl phenyl ethers, and allyl aryl sulfones are catalyzed by Pd(PPh3)4 and give cross-coupling or elimination products, depending on the structure of the initial substrate.
- Kasatkin, A. N.,Kulak, A. N.,Tolstikov, G. A.,Lomakina, S. I.
-
p. 1875 - 1889
(2007/10/02)
-
- Synthesis of the optical antipodes of 4-alkyl-γ-lactones
-
Optical antipodes of 4-alkyl-γ-lactones 3 have been prepared by photochemical rearrangement of optically active α,β-epoxy diazomethyl ketones 1 in ethanol to give 4-hydroxy-alkenoates 2, followed by reduction of the alkene bond and subsequent lactonization.The required epoxy diazomethyl ketones 1 were obtained via the following sequence of reactions: alkylation of 2-propyn-1-ol, subsequent reduction to the alkenols 6, Sharpless epoxidation to 2,3-epoxy alcohols 7, oxidation to glycidic esters 8 and finally conversion to diazo ketones 1.The enantiomeric purities range from 84 to 100percent.
- Thijs, Lambertus,Waanders, Peter P.,Stokkingreef, Edwin H. M.,Zwanenburg, Binne
-
p. 332 - 337
(2007/10/02)
-
- A New Synthesis of (Z)-9-Tetradecen-1-yl Acetate
-
Alkylation of propargyl alcohol dianion with n-butyl bromide provides hept-2-yn-1-ol (II) which is converted into its bromide (III) and subsequently alkylated with monosodio ethyl malonate to furnish the diester (IV).The latter on decarbethoxylation with NaCl/DMSO affords the ester (V).Catalytic hydrogenation of V in the presence of Lindlar's catalyst produces ethyl non-4Z-en-1-oate (VI) which on LAH reduction gives the carbinol (VII) whose corresponding bromide (VIII) on coupling reaction with 1-bromo-5-tetrahydropyranyloxypentane gives IX.Removal of the protective pyranyl moiety from IX followed by treatment with acetic acid-acetyl chloride yields the title compound (I).
- Vig, O. P.,Sharma, M. L.,Kumari, Sarla,Vohra, Neelam
-
p. 962 - 964
(2007/10/02)
-
- Synthesis of Z,Z-Skipped Diene Macrolide Pheromones for Cryptolestes and Oryzaephilus Grain Beetles (Coleoptera Cucujidae)
-
Three macrolide aggregation pheromones for Cryptolestes pusillus, Cryptolestes turcicus, and Oryzaephilus mercator were synthesized stereoselectively from acyclic precursors.The first, 13-methyl-(5Z,8Z)-tridecadienolide (I), is an aggregation pheromone for C. turcicus and had been tentatively identified previously in Phoracantha synonyma.The second, 11-methyl-(3Z,6Z)-undecadienolide (II), is an aggregation pheromone for O. mercator.The third, (3Z,6Z)-dodecadienolide (III) is an aggregation pheromone for O. mercator and is also slightly attractive to C. pusillus.The racemic and enantiomeric forms of I were synthesized.
- Millar, Jocelyn G.,Oehlschlager, Allan C.
-
p. 2332 - 2338
(2007/10/02)
-
- LONG-ACTING CONTRACEPTIVE AGENTS: LEVONORGESTREL ESTERS OF UNSATURATED ACIDS
-
Esters of levonorgestrel (13β-ethyl-17α-ethynyl-17β-hydroxygon-4-en-3-one) with a variety of unsaturated carboxylic acids have been synthesized for evaluation as potential long-acting, injectable contraceptive agents.
- Wan, A. S. C.,Ngiam, T. L.,Leung, S. L.,Go, M. L.,Francisco, C. G.,et al.
-
p. 339 - 348
(2007/10/02)
-
- A Case of Highly Diastereoselective Addition to Unsymmetrical Ketones: lk-Addition of (2-Alkenyl)triphenoxytitanium Derivatives
-
(2-Butenyl)-, (4-methyl-2-pentenyl)-, and (2-heptenyl)triphenoxytitanium (2a-c) add to dialkyl, alkyl aryl-, and alkinyl aryl ketones to give high yields of tertiary homoallylic alcohols (5-12), which are diastereomerically enriched up to 98percent.Config
- Seebach, Dieter,Widler, Leo
-
p. 1972 - 1981
(2007/10/02)
-
- Chain-extension Reactions of Acetylenes. Part 4. Reaction of 1,3-Dilithioacetylides with Carbonyl Electrophiles, Hexamethylphosphoric Triamide, and Benzylideneaniline
-
The regioselectivity of the reactions of 1,3-dilithioalk-1-ynes with various electrophiles has been examined.With formaldehyde and cyclic ketones, reaction occur at C-1 and C-3 to give alk-2-yne-1,5-diols.In contrast reactions with carbon dioxide give allene-1,3-dicarboxylic acids. 1,3-Dilithioalk-1-ynes decompose hexamethylphosphoric triamide and the resulting N-methylmethyleneamine undergoes addition only at the propargylic site.Further reaction with either 1-bromobutane or water gives alkynylamines.Benzylideneaniline also reacts with 1,3-dilithiohex- and hept-1-ynes only at the propargylic site to give N-phenylbut-3-ynylamines.
- Pover, Keith A.,Scheinmann, Feodor
-
p. 2338 - 2345
(2007/10/02)
-
- An approach to the synthesis of C18 tri-insaturated fatty acids.
-
New approaches for the synthesis of cis, trans, trans, octadeca-9,11,13-trienoic acid (I) and its trans, trans, cis isomer (II), starting from the easily available propargyl alcohol are described.
- Petragnani,Brocksom,Gato
-
p. 627 - 634
(2007/10/12)
-