ON THE DIRECT METALATION OF ISOPRENE

Isoprene has been metalated in tetrahydrofuran with an excess of sterically hindered potassium dialkylamides, prepared by combining equimolar amounts of the corresponding lithium amide and potassium tert-butoxide. Subsequent reaction with oxirane, alkyl bromides, and pivaldehyde gave the expected coupling products in reasonable yields. Coupling with (CH3)2CHCH2CH = O and (CH3)2C = CHCH = O afforded the bark beetle pheromones (+/-)-ipsenol and (+/-)-ipsdienol in low yields.