In the reaction of 2-ethoxy-1,3-oxathiolane with carbonylcompounds in the presence of ZnCl2 or HgCl2, it has been found that only the breaking of the endocyclic bond (C–O or C–S bond) occurs, while the breaking of the exocyclic C–O bond to give the 1,3-oxathiolan-2-ium ion is unfavorable. This behavior is different from that of 2-ethoxy-1,3-dithiolane, in which the breaking of the endocyclic C–S bond
Catalytic asymmetric cyanosilylation of ketones, aldehydes, thioketones, thioaldehydes, imines and hydrazones
申请人:——
公开号:US20030236226A1
公开(公告)日:2003-12-25
One aspect of the present invention relates to a method for the catalytic asymmetric cyanosilylation of ketones, aldehydes, thioketones, thioaldehydes, imines and hydrazones. The critical elements of the method are: a non-racemic chiral tertiary-amine-containing catalyst; a substrate selected from the group consisting of ketones, aldehydes, thioketones, thioaldehydes, imines and hydrazones; and a silyl cyanide, e.g., trimethylsilyl cyanide. In preferred embodiments, the substrate is a ketone or aldehyde. A preferred embodiment of the present invention relates to practicing the method in a halocarbon solvent, e.g., chloroform. Another preferred embodiment of the present invention relates to practicing the method in an ester solvent, e.g., ethyl acetate. In certain embodiments, the methods of the present invention produce a silyl cyanohydrin with an enantiomeric excess greater than about 80%. In certain embodiments, the methods of the present invention produce a silyl cyanohydrin with an enantiomeric excess greater than about 90%.
Robbe; Fernandez; Dubief, European Journal of Medicinal Chemistry, 1982, vol. 17, # 3, p. 235 - 243
作者:Robbe、Fernandez、Dubief、et al.
DOI:——
日期:——
Efficient hydrolysis of dithioacetals by the N-fluoro-2,4,6-trimethylpyridinium triflate-water system
作者:Alexander S. Kiselyov、Lucjan Strekowski、Victor V. Semenov
DOI:10.1016/s0040-4020(01)80359-8
日期:1993.3
Dithioacetals including 1,3-dithianes and 1,3-dithiolanes are efficiently cleaved by the title reagent system to the parent carbonyl compounds. The cleavage of diprotected symmetrical alpha-diketones and p-phenylene-diketones gives monoketones in good yields. Amide, 1,3-dioxolane, disulfide, ester, ether, hydroxy, nitrile, nitro, and sulfide functions are relatively stable under the cleavage conditions but thiols are oxidized to disulfides.
Rearrangements of ylides generated from reactions of diazo compounds with allyl acetals and thioketals by catalytic methods. Heteroatom acceleration of the [2,3]-sigmatropic rearrangement
作者:Michael P. Doyle、John H. Griffin、Mitchell S. Chinn、Daan Van Leusen