A stereoselective total synthesis of multiplolide A (1) and of its diastereoisomer 2 was described from easily accessible starting materials (Schemes 2–4). The synthetic strategy involves a Jacobsen resolution, Sharpless epoxidation, Swern oxidation, Yamaguchi reaction, and ring‐closing metathesis (RCM).
The asymmetric Sharpless epoxidation of divinylcarbinol (1), a secondary, achiral allylic alcohol, is described in detail. The epoxidation proceeds with high enantio-control and diastereo-selection. The resulting 1,2-epoxy-4-pentene-3-ols 2 are equilibrated to afford the internal epoxides 5. Hydrolysis of the regioisomers 2 and 5, respectively, furnishes opposite enantiomers of erythro-4-pentenitols
Chemo-Enzymatic Total Synthesis of 3-Epiaustraline, Australine, and 7-Epialexine
作者:Alex Romero、Chi-Huey Wong
DOI:10.1021/jo000933d
日期:2000.12.1
Sequential enzymatic aldol reaction and bis-reductive amination leads to the total syntheses of tetrahydroxylated pyrrolizidine alkaloids, 3-epiaustaline (14), australine (1), and 7-epialexine (11). This approach allows for their rapid construction without the need for protecting group manipulation of the hydroxyl functionality. In addition, an improved procedure for the asymmetric epoxidation of divinyl
Novel enantioselective synthesis of penaresidin A and Allo-penaresidin A via the construction of a highly functionalized azetidine
作者:Ding-Guo Liu、Guo-Qiang Lin
DOI:10.1016/s0040-4039(98)02345-4
日期:1999.1
A new and highly enantioselective synthesis of penaresidin A has been achieved via the construction of a highly functionalized azetidine with the requisite stereogenic centers, which can also be regarded as an advanced intermediate for the synthesis of penaresidin B and penazetidine A. (C) 1998 Elsevier Science Ltd. All rights reserved.