Preparation and Properties of 1,1′-Disubstituted Trichotomine Derivatives with a Twisted C=C Bond

Green trichotomine derivatives bearing alkyl groups on C¹ and C^1′ were prepared. In their absorption spectra, the λ_max shifted to longer wavelengths as the 1,1′-substituents became bulkier, and the bathochromism indicated twisting of the central C²=C^2′ double bond. A 1,1′-dimethyltrichotomine derivative underwent autooxidation to give orange-red 1,11b-dihydroxylated and 1,11b-seco-dicarbonyl compounds, in which twisting of the central C²=C^2′ double bond might be relieved by the decreasing steric interactions between the substituents on C¹ and the C^3′ carbonyl groups.