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.
Synthetic Studies on a Marine Natural Product, Palmerolide A: Synthesis of C1-C9 and C15-C21 Fragments
作者:Krishna Kaliappan、Parthasarathy Gowrisankar
DOI:10.1055/s-2007-982539
日期:2007.6
An efficient cross metathesis and Pd-catalyzed allylic rearrangement have been successfully used to construct the northern hemisphere of a cytotoxic marine natural product, palmerolide A.
有效的交叉复分解和 Pd 催化的烯丙基重排已成功用于构建具有细胞毒性的海洋天然产物 Palmerolide A 的北半球。