Regioselectivity in Diels-Alder Reactions of Thiazolo[3,2-d][1,4,2]diazaphospholes and Related Compounds

Abstract

Thiazolo[3,2-d][1,4,2]diazaphospholes as well as their 5,6-dihydro and benzo derivatives undergo Diels-Alder reactions at the >C=P- functionalities with 2,3-dimethylbutadiene and with isoprene. 1,3-Azaphospholo[5,1-b]benzothiazole, however, exhibits reduced reactivity and reacts with 1,3- dienes only in the presence of an oxidising agent (O 2 , S 8 or Se n ). Reactions with isoprene occur regioselectively.