Reaction of selenobenzophenones with olefins. Formation of 1H-2-benzoselenopyrans. Reaction of 1H-2-benzoselenopyrans with diazoalkanes
Selenobenzophenone reacts as a diene with dimethyl acetylenedicarboxylate (DMAD) to lead to dimethyl 1H-1-diphenylmethyl-1-phenyl-2-benzoselenopyran-3,4-dicarboxylate (5c) in moderate yield; the initial [4 + 2] cycloaddition is followed by the addition of another 1 mol equiv of selenobenzophenone. The reaction might proceed through carbene insertion of the primary cycloadduct. On the other hand, 4,4'-dimethoxyselenobenzophenone combines as a diene with DMAD furnishing dimethyl 1H-1-p-methoxyphenyl-6-methoxy-2-benzoselenopyran-3,4-dicarboxylate (4a). The reaction of benzoselenopyran derivative (4) with diaryldiazomethanes afforded another type of carbene insertion product.
Okuma
K
Department of Chemistry, Faculty of Science, Fukuoka University, Japan.
Koga
Y
Kojima
K
Shioji
K
Matsuyama
H
Yokomori
Y