1.3-dipolar cycloaddition reactions of trans-2-methylene-1,3-dithiolane 1,3-dioxide with 3-oxidopyridinium and 3-oxidopyrylium betaines: a highly diastereoselective route to the tropane skeleton

Research output: Contribution to journalArticle

Authors

  • VK Aggarwal
  • GK Newton
  • PL Spargo
  • AD Hobson
  • H Adams

Colleges, School and Institutes

Abstract

The C2-symmetric vinyl sulfoxide, trans-2-methylene-1,3-dithiolane 1,3-dioxide, was found to react with a range of 3-oxidopyridinium betaines (bearing different substituents on nitrogen) in high yield and with total diastereoselectivity. A 2.3:1 mixture of regioisomers was formed with all of the 3-oxidopyridinium betaines but the ratio was found to change over prolonged periods of time due to reversibility of the minor regioisomer. 3-Oxidopyridinium betaines bearing methyl substituents at either the 2- or 6-position were also tested in the cycloaddition process. Improved regioselectivity (8:1) and again high diastereoselectivity were observed with the betaine having an additional substituent at the 2-position, but with betaines having a substituent in the 6-position although high regioselectivity was observed (9.9:1), the major isomer was formed with low diastereoselectivity (5.5:4.4). The origin of the regio- and diastereo-selectivity with all the betaines is discussed. Finally, the C2-symmetric vinyl sulfoxide, trans-2-methylene-1,3-dithiolane 1,3-dioxide was reacted with an oxidopyrylium betaine in moderate yield. Good regioselectivity and moderate diastereoselectivity were observed.

Details

Original languageEnglish
Pages (from-to)1884-1893
Number of pages10
JournalOrganic and Biomolecular Chemistry
Volume1
Publication statusPublished - 1 Jan 2003