Formation and reaction of carbonyl ylides. Structure of 2:1-cycloadducts of 1-methoxy-2-benzopyrylium-4-olate with isocyanates
Abstract
The Cu(acac)2-catalysed (Hacac = pentane-2,4-dione) decomposition of o-methoxycarbonyl-α-diazoacetophenone in the presence of aryl isocyanates gave 2:1-adducts of the intermediate 1-methoxy-2-benzopyrylium-4-olate with isocyanates; the crystal structure of one such adduct has been determined.