Ramberg-Backlund reaction, Michael-induced

The Michael induced Ramberg-Backlund reactions gives a mixture of ( )- and (Zy dienes via extrusion of S02 from the episulfone intermediate 57 (equation 55)47. 

The Michael-induced Ramberg-Backlund reaction has been used as the key step in a sequence for the homologation of head-to-tail linked conjugated isoprenoids (Scheme 84). Alternatively, homologation can be performed using the Cs-synthon (206) (Scheme 85), but yields are only moderate. ... 

Numerous variants of the Ramberg-BScklund reaction exist. The most prevalent are the vinylogous and Michael-induced Ramberg-BScklund reactions. Decarboxy-lative, epoxy-, and tandem Diels-Alder Ramberg-Backlund reactions are also found in the literature. 

In 1977, de Waard at the University of Amsterdam conceived and prosecuted a novel approach that he dubbed the Michael-induced Ramberg-Backlund (MIRB) olefin synthesis. 24,25 The reaction of dienyl sulfone 25 with one equivalent of sodium phenylsulfinate produced the Michael-induced Ramberg-Backlund product 26 in 40% yield. 

The reaction of halogenomethylvinylsulphones with sulphinate anions, termed the Michael-induced Ramberg-Backlund olefin synthesis, represents an interes-... 

Incorporation of deuterium at the vinylic positions of alkenes can be carried out very efficiently by performing the Ramberg-BScklund reaction in D2O. Finally, the recently developed Michael-induced and vinylogous modifications of the Ramberg-Backlund reaction offer useful approaches to conjugated dienes and polyenes. 

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