Chiral C 2 -symmetric 2,3-disubstituted aziridine and 2,6-disubstituted piperidine as chiral ligands in the addition reaction of diethylzinc with arylaldehydes
作者:Min Shi、Jian-Kang Jiang、Yan-Shu Feng
DOI:10.1016/s0957-4166(00)00479-1
日期:2000.12
Chiral C2-symmetric 2,3-disubstituted aziridines and 2,6-disubstituted piperidines having a β-amino alcohol moiety have been successfully synthesized and their catalytic chiral induction properties have been examined in the asymmetricaddition reactions of diethylzinc with arylaldehydes in hexane. When N-(2,2-diphenyl-2-hydroxyethyl)-(S,S)-2,3-bis(methoxymethyl)aziridine 11 was used as a catalytic
A new synthesis of both enantiomers of C2-symmetric trans-2,6-bis(hydroxymethyl)piperidine derivatives 1 by the use, as a key reaction, of the Sharpless asymmetric dihydroxylation of a symmetric diene 2 is presented.
Symmetry-Assisted Synthesis of <i>C</i><sub>2</sub>-Symmetric <i>trans</i>-α,α‘-Bis(hydroxymethyl)pyrrolidine and -piperidine Derivatives via Double Sharpless Asymmetric Dihydroxylation of α,ω-Terminal Dienes
A new strategy has been developed for the synthesis of C-2-symmetric trans-alpha,alpha'-bis(hydroxymethyl)pyrrolidine and piperidine derivatives 1-3 starting from symmetric alpha,omega-terminal dienes 4-6. The double-asymmetric dihydroxylation (AD) reaction of 4-6 gave C-2-symmetric tetrols, which were converted in a four-step sequence to C-2-symmetric azacycloalkanes 17, 9, and 22, respectively. These azacycloalkanes were transformed into 1-3 in high enantiomeric excess (82% --> 98%ee). The double AD reaction proved to cause enantiomeric enhancement, even though the asymmetric induction for the first AD reaction is moderate. In addition, it was observed that the chromatography on silica gel of several C-2-symmetric azacycloalkanes (17, 20, and 22) of varying ee's resulted in marked enantiomeric fractionation.
Shi; Jiang; Shen, Journal of Chemical Research - Part S, 2001, # 9, p. 375 - 377