Novel Ring Transformation of Quinolines to Indole Derivatives in Two Steps via 1,4-Dihydroquinoline Derivatives.

Abstract Diphenyl 1-phenoxycarbonyl-1,4-dihydroquinoline-4-phosphonates 5c – g , obtained from the reaction of corresponding quinoline derivatives 1 with phenyl chloroformate and triphenyl phosphite in one step, were ozonized in CHCl 3 and CH 3 COOH. Treatment of the resulting mixture with NaHCO 3 produced the 3-formyl-1-phenoxycarbonylindole derivatives 8a – e in high yields. The ring transformation of quinolines 1 to indoles 8 proceeds under mild conditions.