Selenium-induced cyclization of O-allyl oximes as a synthetic route to N-alkyl isoxazolidines
摘要:
Phenylseleneyl bromide easily reacts with O-allyl oximes to afford cyclic iminium bromides which can be reduced in situ with sodium borohydride to produce substituted N-alkyl isoxazolidines in good yield.
The synthesis of the new chiral non-racemic sulfur-containing diselenide, di-2-methoxy-6-[(1S)-1-(methylthio)ethyl]phenyl diselenide, is described. When treated with ammonium persulfate this diselenide is transformed into the corresponding selenenyl sulfate, which acts as a strong electrophilic reagent and adds to alkenes, in the presence of methanol or water, to afford the products of selenomethoxylation
The organoselenium-induced ring-closure reactions of O-allyl oximes give cyclic iminium salts which react with water to afford isoxazolidines in good yield.
The selenyl triflate generated from the reaction of di-2-[(1S)-1-(methylthio)ethyl]phenyl diselenide with silver triflate reacts with various substituted O-allyl oximes to promote ring closure, which affords optically active isoxazolidines in high yields and with good diastereoselectivity (up to 93:7). Enantiomerically enriched 1,3-aminoalcohols can be easily obtained by NO bond cleavage of these