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

VK Aggarwal*, Richard S Grainger, Gary K Newton, Peter L Spargo, Adrian D Hobson, Harry Adams

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

32 Citations (Scopus)

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.

Original languageEnglish
Pages (from-to)1884-1893
Number of pages10
JournalOrganic and Biomolecular Chemistry
Volume1
Issue number11
DOIs
Publication statusPublished - 13 May 2003

Keywords

  • CHIRAL KETENE EQUIVALENT
  • L-GLUTAMIC ACID
  • GONG-TENG-A
  • ENANTIOSELECTIVE SYNTHESIS
  • (1R,3R)-2-METHYLENE-1,3-DITHIOLANE 1,3-DIOXIDE
  • ENANTIOSPECIFIC SYNTHESIS
  • ASYMMETRIC-SYNTHESIS
  • CYCLO-ADDITION
  • (+)-FERRUGININE
  • NITRONES

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