FUJIMOTO • BELLEAU Cyclohexenone

FUJIMOTO - BELLEAU Cyclohexenone Synthesis Synthesis of fused cyclohexenones from lactones (an alternative to the Robinson annulation). 

The mannose-derived lactone 40, produced by ozonolysis of the corresponding alkene, undergoes a modified Fujimoto-Belleau reaction yielding the vinyl phosphonate cyclohexenone 41.1 The epimeric lactone 43 however, yields the anticipated cyclcohexenone 42 (Scheme 12). Formation of 41 is rationalized by invoking hydroxide elimination from an enolate intermediate rather than the anticipated elimination of (MeO)2P(0)OH. 

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