Stereoselectivity in the sigmatropic rearrangement of eight- and nine-membered cyclic allylsulfonium ylides. Synthesis of vinyl- substituted butyro- and valerolactones

Article abstract of DOI:10.1016/S0040-4020(01)85601-5

The rhodium (II) acetate-catalyzed [2,3]sigma-tropic rearrangement of the diazo malonates of (z)-4-phen-ylthio-2-buten-1-ol derivatives 6 afforded vinyl-substituted butyrolactones 10 in a highly stereoselective manner, while the rearrangement of the diazo malonates of homologues, (z)-5-phenylthio-3-penten-1-ol derivatives 9, yielded vinyl-substituted valerolactones 13 and 14 in the predominance of the formers. A stereochemically fixed substituent R in 9 was found to be an important factor resulting to high stereoselectivity in the latter rearrangement as shown by using diazo malonate 20b as substrate.