coupling reaction of aromatic and aliphatic ketones including acyclic aliphatic ketones proceeded smoothly to give the corresponding pinacols in good to high yields below room temperature by the combined use of titanium(II) chloride and zinc in the presence of pivalonitrile. Meso-selective formation of the coupling products was observed in the cases with some acyclic aliphatic ketones.
Mischmetall, an alloy of the light lanthanides, has been used in a variety of organicreactions, either as a coreductant in samarium(II)-mediated reactions (Barbier and Grignard-type reactions, pinacoliccouplingreactions) or as the promoter of Reformatsky-type reactions. It has been also employed as the starting material for easy syntheses of lanthanide trihalides, the reactivity of which has been
Proteasome inhibitors and methods of using the same
申请人:Bernardini Raffaella
公开号:US20060189806A1
公开(公告)日:2006-08-24
The present invention provides boronic acid compounds, boronic esters, and compositions thereof that can modulate apoptosis such as by inhibition of proteasome activity. The compounds and compositions can be used in methods of inducing apoptosis and treating diseases such as cancer and other disorders associated directly or indirectly with proteasome activity.
Aldehydes and ketones, on treatment with a low-valent cerium reagent, undergo reductive dimerization to produce the corresponding pinacols in high yield.
We report a dual function asymmetric catalysis by a chiral phosphoric acid catalyst that controls both enantioselective addition of an achiral α‐vinyl allylboronate to aldehydes and pseudo‐axial orientation of the α‐vinyl group in the transition state. The reaction produces dienyl homoallylic alcohols with high Z ‐selectivities and enantioselectivities. Computational studies revealed that minimization