Collect. Czech. Chem. Commun.
2009, 74, 785-798
https://doi.org/10.1135/cccc2009001
Published online 2009-04-21 10:20:52
Preparation and rearrangement study of novel thiophenium- and selenophenium-ylides
Aleš Macharaa, Václav Kozmíka, Michaela Pojarováb, Hana Dvořákovác and Jiří Svobodaa,*
a Department of Organic Chemistry, Institute of Chemical Technology, Prague, Technická 5, CZ-166 28 Prague 6, Czech Republic
b Department of Solid State Chemistry, Institute of Chemical Technology, Prague, Technická 5, CZ-166 28 Prague 6, Czech Republic
c Central Laboratories, Institute of Chemical Technology, Prague, Technická 5, CZ-166 28 Prague 6, Czech Republic
Abstract
A series of the title ylides was prepared by reaction of fused thiophene and selenophene derivatives with di-tert-butyl diazomalonate. Their thermal stability depended highly on their structure. While the terminal thiophenium- and selenophenium-ylides smoothly rearranged to the corresponding thiopyran and selenopyran derivatives, the internal thiophene ylides showed remarkable stability. The latter also exhibited hindered rotation around the S–C ylide bond and a high rotational barrier could be established in an NMR study.
Keywords: Heterocycles; Thiophene; Selenophene; Thiopyran; Selenopyran; Ylides; Rearrangement; Ring expansion.
References: 37 live references.
