Terpenoids. Part XXXVIII. Ring B contraction of kauranolides and related compounds into gibberellane-type compounds
- 1 January 1976
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 1
- No. 20,p. 2144-2149
- https://doi.org/10.1039/p19760002144
Abstract
A detailed investigation of ring B contraction has been carried out with several derivatives containing the ent-3β,20-epoxy-3,16α-dimethoxy-17-norkaurane skeleton (1). The 19,6β-lactone 7α-methanesulphonate (3) on treatment with base and subsequent methylation gave the gibberellane aldehyde (8) and the epimeric norkaurane derivative (9). The 6β-hydroxy-7α-methanesulphonate (4) on similar treatment gave a similar result. The 19,6α-lactone 7α-methanesulphonate (6) on treatment with potassium hydroxide in t-butyl alcohol–water and subsequent methylation afforded only the desired product (8), in almost quantitative yield. The ring B contraction reaction did not proceed with the 6β-methanesulphonate 7α-acetate (7). The results are rationalised in terms of stereochemical considerations.This publication has 0 references indexed in Scilit: