Symmetry-Assisted Synthesis of C2-Symmetric trans-α,α‘-Bis(hydroxymethyl)pyrrolidine and -piperidine Derivatives via Double Sharpless Asymmetric Dihydroxylation of α,ω-Terminal Dienes
摘要:
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, Min; Inoue, Yoshihisa, Journal of the Chemical Society. Perkin Transactions 2 (2001), 1998, # 8, p. 1725 - 1729
作者:Shi, Min、Inoue, Yoshihisa
DOI:——
日期:——
Two novel chiral rhodium complexes as catalysts for the enantioselective allylation of arylaldehydes
作者:Min Shi、Gui-Xin Lei、Yukio Masaki
DOI:10.1016/s0957-4166(99)00229-3
日期:1999.6
Two novel chiral rhodium complexes were successfully synthesized from the reaction of a new class of bidentate nitrogen ligands with RhCl3. 3H(2)O in ethanol under reflux. The crystal structure of 4a was unambiguously established by X-ray analysis. Their corresponding cationic metal complexes prepared in situ from the reaction of 4a or 4b with AgBF4 catalyze the enantioselective allylation of arylaldehydes with allylstannane in 5-50% ee, (C) 1999 Elsevier Science Ltd. All rights reserved.