Artemesia ketone synthesis

Allylation of acyloyl-imidazoles and pyrazoles61 with allyl halide mediated by indium in aqueous media provides a facile regioselective synthesis of P, y-unsaturated ketones (Scheme 11.1), which has been applied to the synthesis of the monoterpene artemesia ketone. The same product can be obtained by indium-mediated allylation of acyl cyanide (Eq. 11.35).62 Samarium, gallium, and bismuth can be used as a mediator for the allylation of nitrones and hydrazones to give homoallylic hydroxylamine and hydrazides in aqueous media in the presence of Bu4NBr (Scheme 11.2).63 The reaction with gallium and bismuth can be increased dramatically under microwave activation. 

Very few synthetic applications have appeared in this area, the most noteworthy being the extremely short synthesis of artemesia ketone (408) starting from the allyl sulfide (404 Scheme KW). If an al-kyne unit can replace a carbon-carbon double bond without apparent deleterious effect on the 3,2-rearrangement, so also can an allene unit. Dienes are then produced (Scheme lOS). ... 

---