Carbon-hydrogen bonds Knoevenagel reaction

The first total synthesis of Cet /ojc is that of Masanao Matsui. [228] The starting material is )8-ionone [229] its side-chain double bond can be hydrogenated regioselectively on a copper catalyst. The side-chain is then extended by three carbon atoms by means of a Darzens reaction [230], followed by a Knoevenagel condensation. The (JS/Z)-isomeric mixture (1 1) of acids is separated by fractional distillation of their ethyl esters the ( )-isomer is hydrolysed and cyclised with trifluoroacetic add to sclareolide. Reduction of the latter with Vitride (sodium bis(2-methoxyethoxy)aluminium hydride) and ether formation then produces Cetalo . ... 

---