Improvements in or relating to 4h-benzo[4,5]cyclohepta[1,2-b]thiophen-4-one derivatives

摘要

The invention comprises compounds of the formula where R represents chlorine or bromine or a C1- 4 alkoxy radical and Z represents the radical -CH2-CH2- or -CH=CH-. The compounds are prepared by cyclization of a 2-[2-(2-thienyl)ethyl] benzoic acid of the Formula (II) by treatment with polyphosphoric acid, followed, if desired, by dehydrogenation in the 9,10-position by halogenating the 9,10-dihydro-compound and subsequently dehydrohalogenating the halo-compound. Examples relate to the 6-chloro-, 6-bromo-, 6-methoxy- and 7-chloro-derivatives. The benzoic acid derivative (II) is prepared by heating the appropriate o-phthalide with N-bromosuccinimide to give the 3-bromophthalide of the formula which is heated with water to give the phthalaldehydic acid of the formula which is then condensed with 2-thienyl-diethyl-phosphonate to yield the benzoic acid of the formula which is reduced to yield the benzoic acid of the Formula (II).