Syntheses of Cyclopropyl Silyl Ketones

The synthesis of the cyclopropyl silyl ketones 1 – 4 is described. The trimethylsilyl ketone 1 was prepared from geraniol (( E )‐ 5 ) in ca. 10% overall yield by cyclopropanation leading to 6 , CrO 3 oxidation to the aldehyde 8 , reaction of the latter with trimethylsilyl anion to 14A + B , and CrO 3 oxidation to 1 . Also for the ( t ‐butyl)dimethylsilyl ketones 2 – 4 , an efficient four‐step synthesis with overall yields of 48%, 85%, and 13%, respectively, was elaborated, starting from the allylic alcohols ( E )‐ 5 , and 23 . The method of preparation involves as the key step a Wittig rearrangement of the silylallyl 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 .