Ethylidene lophenol

Fig. 8. Formation of 24-methylene lophenol and 24-ethylidene lophenol from 24-methylene cycloartanol [9].

A - A ) (details of these reactions are still obscure) yields 24-methylene lophenol which is then methylated to 24-ethylidene lophenol. 

The second methylation step has recently been demonstrated in vitro in preparations from bramble cell cultures (Fonteneau et al., 1977). The enzyme, which is microsomal, is specific for 24-methylene lophenol (5-F) and will not act on substrates with an intact cyclopropane ring such as 24-methylene cycloartanol (2-F) the product of the reaction is 24-ethylidene lophenol (2-C). A similar enzyme which uses lanosterol (1-A) as substrate was reported in the uredospores of Uromyces phaseoli (Liu and Knoche, 1974), which is one of the few fungi which synthesize C29 sterols (Liu and Knoche, 1976). 

VI. TRANSFORMATIONS INVOLVING 24-METHYLENE LOPHENOL AND 24-ETHYLIDENE LOPHENOL... 

The presence of only 4 deuteriums in poriferasterol (4-B) formed from [C HjJmethionine in Ochromonas implies the formation of an intermediate ethyl-idene compound. Feeding experiments showed that the 28-Z isomers ethylidene lophenol (5-C) and isofucosterol (4-C) are both effectively incorporated into... 

When methylene lophenol and ethylidene lophenol are converted to sterols, the following major changes have to occur in the molecule in addition to those already indicated in Section III (1) removal of the remaining 4a-methyl group, (2) conversion of a A derivative into a A derivative, and (3) insertion of a double bond into the side chain at C-22. 

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