Cyclopropyl trimethylsilyl ethers, synthesis

Another interesting feature of this synthesis is the ring expansion used in sequences A and F. Trimethylsilyl enol ethers are treated with Simmons-Smith reagent to form cyclopropyl silyl ethers. These rings undergo oxidative cleavage and ring expansion when treated with... 

Treatment of em-dibromocyclopropanes with one equivalent of alkyllithium at low temperature generates 1-bromocyclopropyllithiums, which have proved to be very versatile intermediates for the synthesis of various cyclopropyl derivatives. Thus, the reactions of the bromolithium compounds with disulfides ketones, alkyl ha-lides , methyleneammonium salts and trimethylsilyl chloride provide the corresponding 1-bromocyclopropyl derivatives (equation 124). A neighbouring ether... 

This reaction has been carried out on cyclopropanols these substances, however, are less available (2, 118-119) than trimethylsilyl cyclopropyl ethers and are readily decomposed by the hydrogen bromide formed on bromination. In the new synthesis, the by-product is trimethylbromosilane. 

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