Structure of pithecolobine. III. The synthesis of the 1,5- and 1,3-desoxypithecolobines

The second communication of this series has shown that "pithecolobine" is a family of closely related analogues represented by the general formula 1 . In the present paper a crude semiquantitative estimate of the individual components is achieved by a combination of vapor-phase chromatography and chemical degradation.The synthesis of the desoxypithecolobines 3 a and 3 b and their tetratosylates 11 a and b 11 b is described. A comparison of these compounds with the corresponding "natural" mixtures by thin-layer chromatography in several systems, infrared, nuclear magnetic resonance, and mass spectrometry was found to support strongly the conclusions reached by the previous degradative work.