Squalene. chiral methyl

More direct methods for the degradation of the side-chain of cyclolaudenol have been published/ It has been shown, using the squalene 2,3-oxide (38) with a chiral methyl group, that the 1,3-proton loss in the formation of the cyclopropane ring of cycloartenol occurs with retention of configuration at the C-10 methyl group/ ... 

As part of the extensive studies by Cornforth and co-workers of squalene biosynthesis, the stereochemistry of the last step has now been elucidated. This concerns the stereochemistry of proton addition to isopentenyl pyrophosphate with formation of the new methyl group of dimethylallyl pyrophosphate under the influence of isopentenyl isomerase (EC 5.3.3.2). The investigation hinged on the generation of a chiral methyl. CHDT. [2- C,2R- H,3R]- and [2- C,2S- H,3/ ]-mevalonic acid were separately converted in the presence of... 

The direct resolution of underivatised enantiomers has been effected with the aid of some metal-containing chiral stationary phases. Particular attention has been paid to the resolution of chiral alkenes and epoxides using stationary phases derived from chiral metal chelate complexes. The rhodium dicarbonyl P-diketonate complex (5), when dissolved in squalene and coated onto a capillary column, permitted the quantitative enantiomer resolution of 3-methylcyclopentene while methyl oxirane was similarly resolved... 

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