Claisen rearrangement Tebbe methylenation

The opening move was the transformation of the known glucopyranoside 355 into exomethylene vinylpyranose 356. TIBAL-promoted Claisen rearrangement of 356 provided the cyclooctene derivative 357 almost quantitatively, which was then transformed to protected cyclooctanose 358 by methylation followed by hydroboration-oxidation. Installation of the hydroxymethyl function at C5 required three further operations oxidation of the Cs-hydroxyl, Tebbe methylenation, and hydroboration-oxidation. In the event, a mixture of epimeric... 

The asymmetric total synthesis of the putative structure of the cytotoxic diterpenoid (-)-sclerophytin A was realized via a Tebbe-Claisen rearrangement of a tricyclic lactone precursor in the laboratory of L.A. Paquette/ The tricyclic lactone was subjected to the Tebbe methylenation protocol to provide the allyl vinyl ether that was then heated to 130-140 °C in p-cymene to undergo the Claisen rearrangement in good yield. 

Chlorodimethylaluminum (generated from the methylenation reagent) is presumed to be the catalyst in the one-pot Tebbe methylenation -Claisen rearrangement procedure. This process proceeds with 98% E selectivity17s. 

Ester 155 was converted by the Tebbe method to the methylene analogue (92%) which underwent Claisen rearrangement to give the C-linked uronic add derivative 156 (56%). ... 

Using double Tebbe methylenation (77 to 78) followed by a Claisen rearrangement, Paquette and co-workers developed a concise, reliable, and efficient scheme for 4-cyclooctenones. Using this methodology, Paquette reported an alternate enantioselective route to a key bicyclic intermediate,... 

SCHEME 9.5 Fairbanks s approach to a-(l-6)-C-disaccharides by tandem the Tebbe methylenation and Claisen rearrangement. 

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