The reaction of diyne 1 which has nitrogen in a tether with chromium carbene complex 2 afforded isoindoline 4 in good yield. In this reaction, the two carbene carbons (carbene carbon of chromium carbene complex and carbon monoxide) reacted with the two alkynes, respectively, to form an aromatic ring, that is, [2+2+1+1] cocyclization. Using this procedure, isoquinoline derivatives, 6a, 7a, and 9a, were synthesized.
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