Ramberg-Backlund olefination

RAMBERG BACKLUND Olefin Synthesis Conversion of dialkyl suNones to akenes by rearra/tgement of a-haiosulfones with base (via imaranedloxfdes). 

An efficient strategy for the synthesis of /raor-fused oxabicyclic systems involving this annulation followed by a Ramberg-Backlund olefination (Equation 47) as the key step is used for the ring contraction of 116 to give the oxepane 117 in 41% yield, in which the intermediates formed on a-chlorination and sulfone formation steps were used without purification <1996TL2865>. 

The unsaturated trans-oxabicycle 788 was formed from the 1,5-oxathiocin 787, via the Ramberg-Backlund olefination process, whose mechanism is parallel to that observed in the thiazocine series, involving an ct-halogena-tion and oxidation at sulfur, followed by S02 extmsion (Equation 34) <1996TL2865>. 

Chen, T. B. R. A., Burger, J. J., De Waard, E. R. The Michael induced Ramberg-Backlund olefin synthesis. Tetrahedron Lett. 1977, 4527-4530. 

Li, J. J. Ramberg-Backlund olefin synthesis. In Name Reactions for Functional Group Transformations , Li, J. J., Corey, E. J., Eds. John WUey Sons Hoboken, NJ, 2007, pp 386-404. (Review). 

While Ramberg-Backlund olefination failed, desulfonylation of this cyclic b-hydroxysulfone afforded the skipped diene 537 [188]. 

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

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