The synthesis of 9,10-dimethyl-4,6,6a,7,8,9,10,10a-octahydroindolo[3,4-gh]isoquinoline, the 8,9-dimethyl-8-aza analogue of ergoline
The title compound (15) has been synthesised by ring expansion of the cyclopentanone 4-acetyl-9-methyl-4,5,5a,6,6a,7,9,9a-octahydroindeno[6,5.4-cd]indol-8-one (5) by means of the Schmidt reaction. The stereochemistry at C-6a, -9, and -9a of the starting ketone and at C-6a, -10, and -10a of the four lactams produced by the reaction is established by means of the 1H n.m.r. spectral analysis. Two of these isomeric lactams and the corresponding isomers of the title compound have been isolated and characterised.