2- (PHENYLTHIO)-2-PENTEN-5-OLIDE, A NEW BUILDING BLOCK FOR THE SYNTHESIS OF 3-SUBSTITUTED δ-LACTONES
作者:Michiharu Kato、Akihiko Ouchi、Akira Yoshikoshi
DOI:10.1246/cl.1983.1511
日期:1983.10.5
2- (Phenylthio)-2-penten-5-olide, readily accessible from δ-valelolactone, showed high electrophilic reactivities toward some typical carbon nucleophiles to give 3-substituted 2-(phenylthio)pentanolides, which were convertible to a variety of 3-substituted pentan-5-olides and 2-penten-5-olides.
In the presence of a Cu(I) catalyst and a pyridine oxide, alkynyl oxiranes and oxetanes can be converted into functionalized five- or six-membered α,β-unsaturated lactones or dihydrofuranaldehydes. This new oxidative cyclization is proposed to proceed via an unusual allenyloxypyridinium intermediate.
3,4-Dihydro-2H-pyran (DHP) was efficiently transformed into 4-thiophenyl-3,4-dihydro-2H-pyran. This intermediate was converted to the corresponding 1,3-O,Sallylic carbanion with t-butyllithium and selectively alkylated at the carbon a to the sulfur with alkyl halides, an epoxide, and an aldehyde. An one-pot oxidative elimination of the sulfur fragment using vanadium pentoxide generates the desired beta-substituted alpha,beta-unsaturated delta-unsaturated-valero lactone.
KATO, MICHIHARU;OUCHI, AKIHIKO;YOSHIKOSHI, AKIRA, BULL. CHEM. SOC. JAP., 64,(1991) N, C. 1479-1486