- Chemistry of Tertiary Carbon Center in the Formation of Congested C?O Ether Bonds
-
Nucleophilic substitutions, including SN1 and SN2, are classical and reliable reactions, but a serious drawback is their intolerance for both bulky nucleophiles and chiral tertiary alkyl electrophiles for the synthesis of a chiral quaternary carbon center. An SRN1 reaction via a radical species is another conventional method used to carry out substitution reactions of bulky nucleophiles and alkyl halides, but chiral tertiary alkyl electrophiles cannot be used. Therefore, a stereospecific nucleophilic substitution reaction using chiral tertiary alkyl electrophiles and bulky nucleophiles has not yet been well studied. In this paper, we describe the reaction of tertiary alkyl alcohols and non-chiral or chiral α-bromocarboxamides as a tertiary alkyl source for the formation of congested ether compounds possessing two different tertiary alkyl groups on the oxygen atom with stereoretention.
- Hirata, Goki,Takeuchi, Kentarou,Shimoharai, Yusuke,Sumimoto, Michinori,Kaizawa, Hazuki,Nokami, Toshiki,Koike, Takashi,Abe, Manabu,Shirakawa, Eiji,Nishikata, Takashi
-
supporting information
p. 4329 - 4334
(2020/12/23)
-
- Silver-Promoted Fluorination Reactions of α-Bromoamides
-
Silver-promoted C?F bond formation in α-bromoamides by using AgF under mild conditions is reported. This simple method enables access to tertiary, secondary, and primary alkyl fluorides involving biomolecular scaffolds. This transformation is applicable to primary and secondary amides and shows broad functional-group tolerance. Kinetics experiments revealed that the reaction rate increased in the order of 3°>2°>1° α-carbon atom. In addition, it was found that the acidic amide proton plays an important role in accelerating the reaction. Mechanistic studies suggested generation of an aziridinone intermediate that undergoes subsequent nucleophilic addition to form the C?F bond with stereospecificity (i.e., retention of configuration). The synthesis of sterically hindered alcohols and ethers by using AgI is also demonstrated. Examples of reactions of α-bromoamides with O nucleophiles are presented.
- Mizuta, Satoshi,Kitamura, Kanami,Kitagawa, Ayako,Yamaguchi, Tomoko,Ishikawa, Takeshi
-
supporting information
p. 5930 - 5935
(2021/02/01)
-
- Amidation of Carboxylic Acids with Amines by Nb2O5 as a Reusable Lewis Acid Catalyst
-
Among 28 types of heterogeneous and homogenous catalysts tested, Nb2O5 shows the highest yield for direct amidation of n-dodecanoic acid with a less reactive amine (aniline). The catalytic amidation by Nb2O5 is applicable to a wide range of carboxylic acids and amines with various functional groups, and the catalyst is reusable. A comparison of the results of the catalytic study and an infrared study of the acetic acid adsorbed on the catalyst suggests that activation of the carbonyl group of the carboxylic acid by Lewis acid sites on Nb2O5 is responsible for the high activity of the Nb2O5 catalyst. Kinetic studies show that Lewis acid sites on Nb2O5 are more water-tolerant than conventional Lewis acidic oxides (Al2O3, TiO2). In comparison with the state-of-the-art homogeneous Lewis acid catalyst for amidation (ZrCl4), Nb2O5 undergoes fewer negative effects from basic additives in the solution, which indicates that Nb2O5 is a more base-tolerant Lewis acid catalyst than the homogeneous Lewis acid catalyst.
- Ali,Siddiki,Onodera, Wataru,Kon, Kenichi,Shimizu, Ken-Ichi
-
p. 3555 - 3561
(2015/11/10)
-
- Versatile synthesis of quaternary 1,3-oxazolidine-2,4-diones and their use in the preparation of α-hydroxyamides
-
A new approach to the synthesis of 1,3-oxazolidine-2,4-diones, via a two-step reaction sequence, starting from the readily available α-ketols and isocyanates, is reported. The condensation of the latter led to the key precursors 4-methylene-2-oxazolidinon
- Merino, Omar,Santoyo, Blanca M.,Montiel, Luisa E.,Jiménez-Vázquez, Hugo A.,Zepeda, L. Gerardo,Tamariz, Joaquín
-
experimental part
p. 3738 - 3742
(2010/08/19)
-
- Reactions of 2-[(2-arylimino-2-cyano-1,1-dimethylethyl)arylamino]-3-methylbut-2-enenitrile with copper(II) acetate: Synthesis of 2-(2,3-dihydro-2,2-dimethyl-3-oxo-1H-indol-1-yl)-3-methylbut-2-enenitriles
-
Treatment of 2-[(2-arylimino-2-cyano-1,1-dimethylethyl)arylamino]-3-methylbut-2-enenitrile 15, prepared by reactions of N-aryl α-cyanoenamines 3 with Cu(OAc)2·H2O (2 equiv.) in the presence of pyridine (2 equiv.) in EtOH at reflux, and with Cu(OAc)2·H2O (1 equiv.) in HOAc at reflux gave 2-(2,3-dihydro-2,2-dimethyl-3-oxo-1H-indol-1-yl)-3-methylbut-2-enenitriles 11 in moderate to good yields.
- Yun, Sangmin,Kim, Kyongtae
-
p. 2360 - 2369
(2007/10/03)
-
- Bromoamides as starting materials in the synthesis of α-hydroxy- and α- alkoxy derivatives
-
Silver oxide promotes substitution of the bromine at position 2 of α- bromocarboxamides, with a hydroxyl or an alkoxyl group.
- Cavicchioni
-
p. 2223 - 2227
(2007/10/02)
-
- ETHER-AMIDES AND GLYCOSIDE-AMIDES FROM 2-BROMOISOBUTYRAMIDES AND SACCHARIDES BEARING A FREE PRIMARY, SECONDARY OR ANOMERIC ALCOHOLIC GROUP
-
Glycoylamides were obtained in high yields in the presence of silver oxide at room temperature from 2-bromoisobutyramides and the partially protected monosaccharides, 1,2:3,4-di-O-isopropylidene-D-galactopyranose, 5, 1,2:5,6-di-O-isopropylidene-D-glucofuranose, 6, and 2,3,4,6-tetra-O-benzyl-D-glucopyranose, 7.Full characterization through 1H and 13C NMR spectra has been achieved.
- Catelani, Giorgio,Nejad, Farzaneh Moftakhari Kamrani,D'Angeli, Ferruccio,Cavicchioni, Giorgio,Marchetti, Paolo
-
-
- The Conversion of Phenols to Primary and Secondary Aromatic Amines via a Smiles Rearrangement
-
The conversion of phenols to 2-aryloxy-2-methylpropanamides (1) and the Smiles rearrangement of these to N-aryl-2-hydroxy-2-methyl propanamides are described; hydrolysis of the latter compounds yields anilines.The scope and limitations of reaction are discussed.Routes, some involving α-lactams, from phenols to N-substituted derivatives of (1) have been developed.Under the conditions of the Smiles rearrangement these secondary 2-methylpropanamides can form directly anilides, N-alkylanilines, or benzoxazinones.
- Coutts, Ian G. C.,Southcott, Mark R.
-
p. 767 - 771
(2007/10/02)
-
- Scope and Limitations of the TiCl4-Mediated Additions of Isocyanides to Aldehydes and Ketones with Formation of α-Hydroxycarboxylic Acid Amides
-
The adducts obtained from TiCl4 and achiral (8-12) or chiral, nonracemic (13-22) isocyanides are combined with aldehydes (aromatic or aliphatic) and ketones (acetone, cyclohexanone, acetophenone) to give, after aqueous workup, α-hydroxyamides (27-55) .The transformation is compatible with a variety of functional groups (aromatic and heterocyclic rings, amino, ether, ester, and amido groups, halides, and phosphonate substituents).The yields range from 14 to over 95percent (with the lower values in the case of more highly functionalised isocyanides).No diastereoselectivity is observed with chiral isocyanides.If the R groups of the isocyanide (R-NC) form a rather stable cation (t-alkyl or benzylic), cyanohydrins may result from the reaction, rather than the N-substituted α-hydroxyamides (see Scheme 2).
- Seebach, Dieter,Adam, Geo,Gees, Thomas,Schiess, Martin,Weigand, Wolfgang
-
p. 507 - 518
(2007/10/02)
-