Total synthesis of 1-deoxy-7,8a-di-epi-castanospermine and formal synthesis of pumiliotoxin-251D
摘要:
A concise and efficient synthesis of (6R,7S,8R,8aS)-6,7,8-trihydroxyindolizidine (1-deoxy-7,8a-di-epi-castanospermine) 2 is described. The synthesis employs cross metathesis in building the key intermediate 9 and is used effectively in constructing indolizidine skeleton for the total synthesis of 1-deoxy-7, 8a-di-epi-castanospermine and also for the bicyclic framework of pumiliotoxin 251D 12,13. The indolizidine skeleton is achieved in one pot sequence of transformations such as deprotection of Cbz group, reduction of double bond, and cyclization. The configurational and conformational structures of compound 10 are unambiguously confirmed by X-ray analysis. (C) 2012 Elsevier Ltd. All rights reserved.
Total synthesis of 1-deoxy-7,8a-di-epi-castanospermine and formal synthesis of pumiliotoxin-251D
摘要:
A concise and efficient synthesis of (6R,7S,8R,8aS)-6,7,8-trihydroxyindolizidine (1-deoxy-7,8a-di-epi-castanospermine) 2 is described. The synthesis employs cross metathesis in building the key intermediate 9 and is used effectively in constructing indolizidine skeleton for the total synthesis of 1-deoxy-7, 8a-di-epi-castanospermine and also for the bicyclic framework of pumiliotoxin 251D 12,13. The indolizidine skeleton is achieved in one pot sequence of transformations such as deprotection of Cbz group, reduction of double bond, and cyclization. The configurational and conformational structures of compound 10 are unambiguously confirmed by X-ray analysis. (C) 2012 Elsevier Ltd. All rights reserved.
α,β-Unsaturated Diazoketones as Platforms in the Asymmetric Synthesis of Hydroxylated Alkaloids. Total Synthesis of 1-Deoxy-8,8a-diepicastanospermine and 1,6-Dideoxyepicastanospermine and Formal Synthesis of Pumiliotoxin 251D
作者:Barbara Bernardim、Vagner D. Pinho、Antonio C. B. Burtoloso
DOI:10.1021/jo301967w
日期:2012.11.2
A versatile and concise approach for the stereoselective synthesis of mono-, di-, and trihydroxylated indolizidines is presented in four to six steps from Cbz-prolinal and a diazophosphonate. The key steps involved a Wolff rearrangement, followed by a stereoselective dihydroxylation/epoxidation reaction, from an α,β-unsaturated diazoketone. The strategy also permits extension to the synthesis of many