E and Z methyl styryl sulfides undergo highly regioselective cycloadditions with benzo and mesitonitrile oxide. The regioselectivity is lower with sulfoxides and is reversed in the case of sulfones. The directing effect of the thio moieties has been clarified in the framework of the frontier model of cycloaddition reactions. The lower effect of the thio substituents in the cycloadditions of cyclic
Stereoselective Synthesis of Racemic and Optically Active <i>E</i>-Vinyl and <i>E</i>-Dienyl Sulfoxides via Wittig Reaction of α-Sulfinyl Phosphonium Ylides
A series of ol-sulfinyl phosphonium ylides have been obtained in the reaction of phosphonium mono- and diylides with sulfinic acid esters. The use of(-)-(S)-menthyl-p-toluenesulfinate in this reaction afforded the corresponding (S)-((p-tolylsulfinyl)methyl)triphenylphosphonium ylide. The Wittig reaction of these ylides with saturated and unsaturated aldehydes resulted in the formation of racemic and optically active (+)-(R)-vinyl and dienyl sulfoxides with the E-geometry. The synthesis of (+)-(R)-((p-tolylsulfinyl)methyl)triphenyl iodide as a precursor of the optically active ylide has also been described.
Kita, Yasuyuki; Tamura, Osamu; Itoh, Fumio, Chemical and pharmaceutical bulletin, 1987, vol. 35, # 2, p. 562 - 569