Further Explorations into the Synthesis of Dehydro ‐Hedione ®

Dehydrohedione (DHH) 1 may be obtained in 20% overall yield by a Reformatsky reaction with enone methyl ether 3b , followed by acidic workup of the crude reaction mixture. Alternatively, epoxidation (3‐chloroperbenzoic acid, CH 2 Cl 2 , 84% yield) of the tertiary allyl alcohol derivative 4 affords a 1 : 2 mixture of 8a and 8b . The latter epoxy ester 8b may also be obtained stereoselectively either from 4 ( t BuO 2 H, [Mo(CO) 6 ], 1,2‐dichloroethane, 70°, 62% yield; or t BuO 2 H, [VO(acac) 2 ], decane, 20°, 92% yield), or from 5 (AcOMe, LiN(SiMe 3 ) 2 , THF, −78°, 84–87%). BF 3 ⋅Et 2 O‐Catalyzed cascade rearrangement and OH elimination of 8a afford selectively DHH 1 in 88% yield. The cis disposition of the side chains of the weakly odoriferous hedione‐like analogues 2b and 2c was maintained by means of either an epoxy or a cyclopropane moiety.