Total Syntheses of Ningalins D and G

A flexible synthetic strategy for the total syntheses of ningalins D and G is described. The highly effective TMS-OTf/2,6-lutidine-mediated [3,3]-sigmatropic rearrangement of densely loaded dinaphthyl hydrazides and cyclization of the resulting 2,2′-diamino-1,1′-dinaphthyls afforded the key 7<i>H</i>-dibenzo­[<i>c</i>,<i>g</i>]­carbazole intermediates. Successful conversions to biphenylene quinone methides followed by regioselective brominations completed the total syntheses of the titled marine alkaloids