C. Perez et al., ISOXAZOLES AS LATENT ALPHA-CYANOALDEHYDES - CONSTRUCTION OF THE INDOLE[2,3-A]QUINOLIZINE RING-SYSTEM, Tetrahedron, 52(3), 1996, pp. 987-992
A new access to the indolo[2,3-a]quinolizine ring system was devised u
sing the thermal decarboxylative ring-opening of 3-carboxyl isoxazoles
into alpha-cyano aldehydes. Thus, from acetal 8b the indolo[2,3-a]qui
nolizine 5 was obtained in four steps via the beta-carboline 11 which
on heating gave compound 5.