Reactions of 3,6-Diethoxyxanthen-9-one with alkylaluminium compounds

Abstract

3,6-Diethoxyxanthen-9-one reacts with trimethylaluminium to give 3,6- diethoxy-9-methylenexanthene and a little 3,6-diethoxy-9,9- dimethylxanthene. In similar reactions, triethylaluminium gives 3,6- diethoxy-9,9-diethylxanthene, diisobutylaluminium hydride gives 3,6- diethoxyxanthene, and tri-isobutylaluminium gives a mixture of 3,6- diethoxyxanthene and 3,6-diethoxy-9-isobutylxanthene. The 3,6-diethoxy- 9-methylenexanthene has been treated with base and chloroform or bromoform to obtain the corresponding 2,2-dihalo-3?,6?- diethoxyspiro[cyclopropane-1,9?-xanthene].