2002 Diastereoselective syntheses

Diastereoselective synthesesO 0031 Asymmetric 1,3-Dipolar Cycloadditions of Diazoalkanes to

(5S,SS)-5-[(1R)-Menthyloxy]-4-phenylsulfinyl (and phenylsulfonyl)furan-2(5H)-ones. — The reactivity of 5-alkoxy-2(5H)-furanones towards diazoalkanes is strongly enhanced by sulfinyl and sulfonyl groups at C-4. The regioselectivity of these reactions depends on both the regio-orientating ability of the sulfur substituents at C-4 of compounds (I) and (V) (-SO2Ph > SO-Ph) mainly controlling the regiochemistry of the reactions with diazomethane and the steric interactions which favor the regiochem-istry involving the formation of the bond between nitrogen (less hindered end of the dipole) and C(4)furanone (the bulkiest end of the dipolarophile) which predominate in reactions with diazoethane. — (GARCIA RUANO*, J. L.; BERCIAL, F.; GONZALEZ, G.; MARTIN CASTRO, A. M.; MARTIN*, M. R.; Tetrahedron: Asymmetry 13 (2002) 18, 1993-2002; Dep. Quim. Org., Fac. Cienc., Univ. Auton., Cantoblanco, E-28049 Madrid, Spain; Eng.) — Klein

07- 034

2002 Diastereoselective syntheses