PENTAMETHINE SYSTEMS

A review deals with structure, synthesis, and reactivity of compounds containing pentamethine systems (i.e. pentamethinium salts, aminopenta dienals, glutaconic aldehydes, and cyanine dyes). Their syntheses of t hese compounds via ring opening of the heterocycles, by building the s keleton, or by addition reactions are described, as well as their reac tivity to nucleophilic and electrophilic reagents, including ring-clos ure reactions.