Hydrolysis studies of chalcogenopyrylium trimethine dyes. 1. Product studies in alkaline solution (pH≥8) under anaerobic And aerobic conditions

摘要

hydrolyses of chalcogenopyrylium dyes 1-9 give product distributions that are both heteroatom and oxygen dependent. Under anaerobic or aerobic onditions at pH 8, hydrolyses of dyes 1-4, which each contain a pyrylium ring, give 2-pentene-1,5-diones 10-13, respectively, in >90/100 yield from addition of hydroxide to the 2-position of the pyrylium ring followed by ring opening and tautomerization. Telluropyrylium dye 8 under anaerobic conditions over the pH range 6.9-11.0 gives a 1:1 mixture of telluropyranylidene aldehyde 14 and tris(telluropyranylidenementhyl)methane 15 derived from addition of hydroxide to the central carbon of the trimethine bridge.