Enantioselective addition of β-functionalized allylboronates to aldehydes and aldimines. Stereocontrolled synthesis of α-methylene-γ-lactones and lactams
We report results regarding the development of condensations of chiral β-alkoxycarbonylallylboronates on aldehydes and imines. These allylboronates add in a highly enantioselective and diastereospecific manner to afford biologically and synthetically useful chiral α-methylene-γ-butyrolactones and lactams. The nature of the electrophile (aldehyde vs imine) is shown to have a dramatic influence on the
Reversal of stereochemistry in a two-step Staudinger reaction by changing the backbone protecting group. Synthesis of NH-trans-3-benzoyloxy-4-aryl-azetidinones
Changing the protecting group in the glyoxylic acid derived ketene from benzyloxy to benzoyloxy provides a simple way of switching the diastereoselectivity of the substituents on the final β-lactamring from cis to trans.
Enantioselectivity in the allylboration of N-silylimines with a variety of chirallymodifiedallylboronreagents has been examined. Optically active N-sulfonylamino alcohols (16, 17 and 19) derived from D-camphor and norephedrine were found to be efficient chiral ligands for the allylboration reagent. These reagents smoothly reacted with N-silylimines to give the corresponding homoallylic amines in
Enantioselective allylation of N-(trimethylsilyl)benzaldehyde imine using polymer-supported chiral allylboron reagents
作者:Ashraf A El-Shehawy、Magdy Y Abdelaal、Katsuhiro Watanabe、Koichi Ito、Shinichi Itsuno
DOI:10.1016/s0957-4166(97)00184-5
日期:1997.6
trimethallylborane, and tri(3,3-dimethylallyl)borane, respectively, to give polymeric allylating agents. N-(Trimethylsilyl)benzaldehyde imine was allowed to react with the polymeric chiral reagents to afford the corresponding primary homoallylamines in high yield and good enantioselectivities.
Substituted (1,2-Diarylethyl)amide Acyl-CoA:Cholesterol Acyltransferase Inhibitors: Effect of Polar Groups on in Vitro and in Vivo Activity
作者:John W. Clader、Joel G. Berger、Robert E. Burrier、Harry R. Davis、Martin Domalski、Sundeep Dugar、Timothy P. Kogan、Brian Salisbury、Wayne Vaccaro
DOI:10.1021/jm00010a004
日期:1995.5
Substituted (1,2-diarylethyl)amides have been prepared and evaluated for their ability to inhibit microsomal acyl-CoA:cholesterol acyltransferase activity in vitro and to lower hepatic cholesteryl ester content in vivo in a cholesterol-fed hamster. Simple unsubstituted (diarylethyl)amides were potent inhibitors in vitro but showed poor activity in vivo. Introduction of polar groups at specific locations