Long-chain polypropionate

The sunuhaneous double Diels-Alder addition of l,l-bis(3,5-dimethylfur-2-yl)ethane (8) with a biS dienophile such as diethyl ( , )-4-oxohepta-2,5-diene-1,7-dioate was proposed as new, asymmetric synthesis of long-chain polypropionate fragments and analogues <96TL4149>. 

Sevin, A-F, Vogel, P, A new stereoselective and convergent approach to the synthesis of long-chain polypropionate fragments, J. Org. Chem., 59, 5820-5926, 1994. 

Vogel and co-workers have used 1 as double chain elongation synthon in their synthesis of long chain polypropionate fragments (eq 48). Their approach is based on an one-pot reaction cascade which involves hetero-Diels-Alder addition of electron-rich l-alkoxy-3-acyloxy-l,2-dienes (e.g., 25) to sulfur dioxide, subsequent ionization into zwitterionic intermediates (e.g., 26), then reaction of the latter with allylsilanes. The final step of this sequence is the retro-ene desulfinylation of an intermediate allylsilyl sulfinate (e.g., 27) to produce useful synthetic intermediates containing two more stereogenic centers (e.g., 28). 

Vogel P, Sevin AF, Kernen P, Bialecki M. Naked sugars of the second generation asymmetric synthesis of long-chain polypropionates and analogues starting with acetone. Pure Appl. Chem. 1996 68 719-722. 

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