Syntheses of Cyclopropyl Silyl Ketones

Abstract

AbstractThe 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, 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 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.