Synthetic Studies directed toward the Diterpenoid Alkaloids

Synthetic Studies directed toward the Diterpenoid Alkaloids.—In studies directed toward the synthesis of the C19 diterpenoid alkaloids, Chatterjee has reported45 the preparation of intermediate (150) by a very unusual synthetic sequence. 

Cornforth46 has severely criticized this scheme and stated that all claims in this paper should be accepted as fact after, but not before, verification by independent experiment. Amongst other points, he noted that the conversion of (151) into (152) requires (a) an abnormal reaction of a /S-keto-ester with a Grignard reagent, and (b) a so-called dehydration involving the wholly unexplained disappearance of a C-methyl group. 

Methods reported by Meyer and co-workers48 (cf. Vol. 9, p. 235) could be used for the conversion of compound (160) into (161), which has previously been formally converted into atisine, veatchine, and garryine. 

Acknowledgment The authors express their appreciation to Dr. Naresh V. Mody for reviewing the manuscript and making several helpful suggestions. 

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