Yield:51116-72-4 83%

Reaction Conditions:

with thionyl chloride;N,N-dimethyl-formamide at 20; for 4.5 h;Inert atmosphere;Reflux;

Steps:

3 (3E,5E)-5-(tert-Butyl)-7-methylnona-3,5-dien-2-one (R = Me, R¹ = H, Δ^2,5)

At room temperature under N₂ atmosphere, DMF (7 drops, 0.1 10 g, 1.50 mmol) was added to 3-methylpentanoic acid (50.0 g, 0.430 mol). Over a period of 2h, thionyl chloride (77.0 g, 0.647 mol) was added slowly with stirring, upon which the temp. dropped to 12 °C with vigorous gas evolution. After 30 minutes of further stirring at room temperature, the temperature was slowly increased to 80 °C, and the reaction mixture then refluxed for 2h. Distillation of the crude material afforded at 73 °C/200 mbar 3-methylpentanoyl chloride (47.8 g, 83%) as a colorless liquid.

References:

WO2013/170976,2013,A1 Location in patent:Page/Page column 12