Kineticresolutions of N-substituted benzyl-trans-2-acetoxymethyl-5-(hydroxymethyl)pyrrolidines using lipase-catalyzed transesterification have been systematically studied. The enantioselectivity depends significantly on the position of substituent at the aromatic ring and N-3,5-dimethylbenzyl group was found to transform trans-2,5-disubstitutedpyrrolidinederivative into an efficiently-resolved substrate
Lipase-Catalyzed Transesterification of trans-2,5-Disubstituted Pyrrolidines: Effect of Substituent on Enantioselectivity
作者:Yasuhiro Kawanami、Noriko Iizuna、Kiyoka Okano
DOI:10.1246/cl.1998.1231
日期:1998.12
Kineticresolution of racemic N-arylmethylated trans-2-acetoxy-methyl-5-hydroxymethylpyrrolidines by using lipasecatalyzed transesterification has been studied. The enantioselectivity depends significantly on the structure of the aryl ring and N-3,5-dimethylbenzylpyrrolidine was found to be the best substrate for the present reaction.
Facile Non-Racemizing Route for the N-Alkylation of Hindered Secondary Amines
作者:Shabana S. Insaf、Donald T. Witiak
DOI:10.1055/s-1999-3399
日期:1999.3
A simple, generally high yielding, method for the N-alkylation of sterically hindered secondary amines bearing α-substituents is described. Alkyl tosylates in the presence of 1,2,2,6,6-pentamethylpiperidine and toluene are essential for the production of the respective tertiary amines. Chiral amino acid derivatives studied do not racemize under the reaction conditions.
Studies of N-terminal templates for .alpha.-helix formation. Synthesis and conformational analysis of (2S,5S,8S,11S)-1-acetyl-1,4-diaza-3-keto-5-carboxy-10-thiatricyclo[2.8.1.04,8]tridecane (Ac-Hel1-OH)
作者:D. S. Kemp、Timothy P. Curran、William M. Davis、James G. Boyd、Christopher Muendel
DOI:10.1021/jo00023a037
日期:1991.11
A convergent synthesis of the title compound, a conformationally restricted analogue of acetyl-L-prolyl-L-proline, from 1-acetyl-2(S)-carboxy-4(S)-mercaptopyrrolidine and trans-1-(tert-butoxycarbonyl)-2(S)-(methoxy-carbonyl)-5(S)-[(tosyloxy)methyl]pyrrolidine (Ac-Hel1-OH) is reported, along with a synthesis of (2S,8S,11S)-1-acetyl-1,4-diaza-3-keto-10-thiatricyclo[2.8.0(4,8)]tridecane. In the crystal and in CDCl3 solution the conformation of Ac-Hel1-OH is shown to approximate a staggered orientation at the 8,9-CC bond and an s-cis orientation at the acetyl amide bond. In DMF, DMSO, MeCN, and D2O significant amounts of the s-trans conformer are also present.
Base-catalyzed epimerization behavior and unusual reactivity of N-substituted derivatives of 2,5-dicarbalkoxypyrrolidine. Preparation of a novel mixed carbamic carbonic anhydride by a 4-(dimethylamino)pyridine-catalyzed acylation