Synthesis of Bromo- and Carboxylic Acid-Substituted Methylenepyrans

In this contribution we describe a series of pyranylidene derivatives bearing bromine atoms in various positions. Some of these bromo derivatives have been converted in carboxylic acid by halogen-metal exchange reaction using gaseous CO2 as electrophile. Selected compounds have been studied by UV-visible absorption and cyclic voltametry to study the influence of the substituent on the pyranylidene core.