The total syntheses of (+)-crotanecine, (-)-hastanecine and (-)-rosmarinecine utilizing the tandem (4+2)/(3+2) cycloadditions of nitroalkenes

A short and efficient asymmetric synthesis of the pyrrolizidine necine base (${-}$)-hastanecine is described. The key reaction in the synthesis is a sequential inter (4+2) /inter (3+2) cycloaddition. The Lewis acid promoted (4+2) cycloaddition between 2-acyloxy nitroalkene 90 and chiral vinyl ether (+)-28 afforded a nitronate which underwent facile (3+2) cycloaddition with dimethyl maleate. The resulting nitroso acetal (${-}$)-96 had all the required stereocenters for (${-}$)-hastanecine. The critical unmasking of the nitroso acetal (${-}$)-96 employed a hydrogenolytic cleavage to give the 1-azabicyclo (3.3.0) octane skeleton of (${-}$)-hastanecine.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Chemistry, Organic

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Thorarensen, Atli

Contributors dc:contributor

• Denmark, Scott E.

• Chemistry, Organic

Statement dc:rights

• Copyright 1996 Thorarensen, Atli

Language dc:language

eng

Identifier

9780591199413
AAI9712459
(UMI)AAI9712459

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/19961