Studies in Natural Product Chemistry

The first section of this thesis is concerned with a biogenetic-type approach to the synthesis of the aconitine-lycoctonine group of diterpene alkaloids. The synthetic precursor, atisine, was transformed in an eleven step sequence into a keto-tosylate. This material underwent a novel, stereospecific pyrolytic rearrangement to give a key intermediate in the proposed atisane-aconane biogenesis, whose constitution and stereochemistry were confirmed by anx-ray crystallographic analysis, conducted on a heavy atom derivative. Our efforts to convert this intermediate into the desired aconitine-lycoctonine skeleton, a task which had already been accomplished in principle by other workers, met with limited success. N. M. R. studies on some acetamides, obtained in the foregoing synthesis, revealed an interesting example of restricted rotation around the bond. Variable temperature work enabled a crude barrier to rotation to be extracted. The second section of the thesis, also in the realm of diterpenes, concerns the synthesis of the cassane skeleton, in a biogenetically-patterned fashion, from isopimaric acid. The route from isopimaric acid to an important intermediate enone is described. Despite numerous attempts,we could not induce the Wagner-Meerwein rearrangement in this enone,which would have resulted in the desired cassane skeleton