Reductive Alkylation of Pentaphenylthiopyrylium Perchlorate: An Approach to Regiospecific Synthesis of Hexasubstituted 2H-Thiopyrans

Abstract

Regiospecific synthesis of some new hexasubstituted 2H-thiopyrans was examined by reductive alkylation of pentaphenylthiopyrylium perchlorate and found to be in quantitative yields. Under our experimental conditions, the formation of unstable thiabenzene intermediates could be observed through detectable color changing during the addition of C-nucleophiles to thiopyrylium perchlorate. Moreover, the effect of phenyl groups on the 3,5-positions of thiopyrylium perchlorate on the regioselectivity were compared with other analogs having methyl groups on the same positions.

Keywords:

• C-Nucleophile
• pentaphenylthiopyrylium
• reductive alkylation
• 2H-thiopyrans

Acknowledgments

Thanks are due to Prof. H. Pirelahi for his help. Partial support of this investigation by the Research Council at the University of Shahid Chamran is gratefully acknowledged.