112245-13-3Relevant articles and documents
An Iridium(I) N-Heterocyclic Carbene Complex Catalyzes Asymmetric Intramolecular Allylic Amination Reactions
Ye, Ke-Yin,Cheng, Qiang,Zhuo, Chun-Xiang,Dai, Li-Xin,You, Shu-Li
, p. 8113 - 8116 (2016)
A chiral iridium(I) N-heterocyclic carbene complex was reported for the first time as the catalyst in the highly enantioselective intramolecular allylic amination reaction. The current method provides facile access to biologically important enantioenriched indolopiperazinones and piperazinones in good yields (74–91 %) and excellent enantioselectivities (92–99 % ee). Preliminary mechanistic investigations reveal that the C?H activation occurs at the position ortho to the N-aryl group of the ligand.
Highly Selective Asymmetric Acetate Aldol Reactions of an N-Acetyl Thiazolidinethione Reagent
Zhang, Yingchao,Phillips, Andrew J.,Sammakia, Tarek
, p. 23 - 25 (2004)
(Equation presented) A highly diastereoselective acetate aldol reaction that uses a tert-leucine-derived thiazolidinethione auxiliary and dichlorophenylborane has been developed. The reaction proceeds in excellent yields and with high diastereoselectivities (drs range from 9.5:1 to >100:1).
A scalable synthesis of the (S)-4-(tert-butyl)-2-(pyridin-2-yl)-4,5- dihydrooxazole ((S)-t-BuPyOx) ligand
Shimizu, Hideki,Holder, Jeffrey C.,Stoltz, Brian M.
, p. 1637 - 1642 (2013)
An efficient method for the synthesis of the (S)-4-(tert-butyl)-2-(pyridin- 2-yl)-4,5-dihydrooxazole ((S)-t-BuPyOx) ligand has been developed. Inconsistent yields and tedious purification in known routes to (S)-t-BuPyOx suggested the need for an efficient, dependable, and scalable synthetic route. Furthermore, a route suitable for the synthesis of PyOx derivatives is desirable. Herein, we describe the development of a three-step route from inexpensive and commercially available picolinic acid. This short procedure is amenable to multi-gram scale synthesis and provides the target ligand in 64% overall yield.
Acetylene - Dicobaltcarbonyl complexes with chiral phosphinooxazoline ligands: Synthesis, structural characterization, and application to enantioselective intermolecular Pauson-Khand reactions
Castro, Jaume,Moyano, Albert,Pericas, Miquel A.,Riera, Antoni,Alvarez-Larena, Angel,Piniella, Joan F.
, p. 7944 - 7952 (2000)
The reaction of the phenylacetylene - dicobalthexacarbonyl complex (2) with the 4-R-2-(2-diphenylphosphinophenyl)oxazolines 1 (R = Ph) and 4 (R = CH2CH2SCH3) leads to the selective formation of the chelated complexes 3 and 5, respectively. On the other hand, the tert-butyl-substituted phosphinooxazoline 6 acts as a monodentate ligand, and its reaction with several 1-alkyne-derived complexes (2,7 - 10) affords readily separable mixtures of the diastereomer nonchelated complexes 11a,b - 15a,b. The interconversion rate between diastereomeric pairs is dependent on the steric bulk of the alkyne substituent, and neither 3 nor 5 epimerize at room temperature. The structures of both kinds of complexes have been ascertained by a combination of spectroscopical (IR, NMR), X-ray diffraction, and chiroptical methods; this has allowed the development of a practical procedure for the establishment of the absolute configuration of the chiral alkyne - dicobaltcarbonyl complexes obtained by the selective substitution of a carbon monoxide on one of the diastereotopic cobalt atoms. The intermolecular Pauson - Khand reaction of the chelated complexes 3 and 5 with norbornadiene respectively affords the (+) and (-) enantiomers of expected enone adduct 25, but in low enantiomeric excesses. Contrary to that, the tertiary amine N-oxide-promoted intermolecular Pauson - Khand reactions of nonchelated complexes 11a,b - 13a,b give the corresponding norbornadiene- or norbornene-derived adducts both in high yields (85-99%) and enantioselectivities (93-97% enantiomeric excess), in what constitutes a substantial improvement over preexisting procedures for this reaction. The possibility of achieving chiral induction in the Pauson - Khand reaction of symmetrical alkynes (via the corresponding dicobaltpentacarbonyl complexes with ligand 6) has been demonstrated for the first time. An enantioselectivity mnemonic rule and a mechanistic model that explains the observed asymmetric sense of induction have been developed, and have been found to be in agreement with the results of model semiempirical molecular orbital calculations.
An Improved Procedure for the Preparation of 2,2-Bis[2-[4(S)-tert -butyl-1,3-oxazolinyl]] propane [(S,S)-tert-Butylbis(oxazoline)] and Derived Copper(II) Complexes
Evans, David A.,Peterson, Gretchen S.,Johnson, Jeffrey S.,Barnes, David M.,Campos, Kevin R.,Woerpel, Keith A.
, p. 4541 - 4544 (1998)
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Total Synthesis of the Alleged Structure of Crenarchaeol Enables Structure Revision**
Cunha, Ana V.,Havenith, Remco W. A.,Holzheimer, Mira,Minnaard, Adriaan J.,Schouten, Stefan,Sinninghe Damsté, Jaap S.
supporting information, p. 17504 - 17513 (2021/07/06)
Crenarchaeol is a glycerol dialkyl glycerol tetraether lipid produced exclusively in Archaea of the phylum Thaumarchaeota. This membrane-spanning lipid is undoubtedly the structurally most sophisticated of all known archaeal lipids and an iconic molecule in organic geochemistry. The 66-membered macrocycle possesses a unique chemical structure featuring 22 mostly remote stereocenters, and a cyclohexane ring connected by a single bond to a cyclopentane ring. Herein we report the first total synthesis of the proposed structure of crenarchaeol. Comparison with natural crenarchaeol allowed us to propose a revised structure of crenarchaeol, wherein one of the 22 stereocenters is inverted.
N-1 BRANCHED ALKYL ETHER SUBSTITUTED IMIDAZO[4,5-C]QUINOLINE COMPOUNDS, COMPOSITIONS, AND METHODS
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Page/Page column 47, (2020/06/19)
Imidazo[4,5-c]quinoline compounds having a substituent that is attached at the N-1 position by a branched group, single enantiomers of the compounds, pharmaceutical compositions containing the compounds, and methods of making the compounds are disclosed. Methods of use of the compounds as immune response modifiers, for inducing cytokine biosynthesis in humans and animals, and in the treatment of diseases including infectious and neoplastic diseases are also disclosed.
