Syntheses of Cyclopropyl Silyl Ketones

Article abstract of DOI:10.1002/hlca.19860690107

The synthesis of the cyclopropyl silyl ketones 1-4 is described.The trimethylsilyl ketone 1 was prepared from geraniol ((E)-5) in ca. 10percent overall yield by cyclopropanation leading to 6, CrO3 oxidation to the aldehyde 8, reaction of the latter with trimethylsilyl anion to 14A+B, and CrO3 oxidation to 1.Also for the (t-butyl)dimethylsilyl ketones 2-4, an efficient four-step synthesis with overall yields of 48percent, 85percent, and 13percent, respectively, was elaborated, starting from the allylic alcohols (E)-5, (Z)-5, and 23.The method for the preparation involves as the key step a Wittig rearrangement of the silylalyl ethers ((E/Z)-20, 24) to the silyl alcohols ((E/Z)-21, 25), subsequent cyclopropanation (19A+B, 22A+B, 26), and oxidation to the cyclopropyl silyl ketones 2-4.