Benzyne from benzothiadiazole-1,1-dioxide

Wittig and Hoffmann (1961) obtained benzyne from a compound of somewhat similar structure, 1,2,3-benzothiadiazole 1,1-dioxide, at 0°. 

It is known that benzenediazonium-2-carboxylate decomposes to give benzyne via the zwitter-ion (128) 161>. We therefore checked that benzyne is involved in our reactions by carrying out reactions with cinnamaldehyde using benzyne generated from benzothiadiazole-1,1-dioxide 162), diphenyhodonium-2-carboxylate i 3,164)( weil as fr0m anthranilic acid165). Flavene was isolated from each reaction and hence our reactions do involve aiynes and are not arynoid 13 8). 

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