Benzynes from benzothiadiazole-1,1-dioxide

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). 

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

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