摘要:
A process is provided for the catalytic asymmetric reduction of ketones to provide alcohol reaction products which are enriched in one enantiomer. The asymmetric reduction is accomplished utilizing an achiral metal precatalyst in combination with an optically active additive.
摘要:
A process for preparing chiral metallocene dihalides as catalytic agents in improved yields by deprotonation of 1,2-bis(2,3-disubstituted cyclopentadienyl)ethane followed by condensation with hafnium tetrachloride or zirconium tetrachloride.
摘要:
A process is provided whereby organic carbonyl substrates, including esters, lactones, ketones, amides and imides are reduced in a reaction with a silane reducing reagent and a catalyst. Exemplary catalysts include metal alkoxides and metal aryloxides.
摘要:
One aspect of the present invention relates to novel ligands for transition metals. A second aspect of the present invention relates to the use of catalysts comprising these ligands in transition metal-catalyzed carbon-heteroatom and carbon-carbon bond-forming reactions. The subject methods provide improvements in many features of the transition metal-catalyzed reactions, including the range of suitable substrates, reaction conditions, and efficiency.
摘要:
One aspect of the present invention relates to copper-catalyzed carbon-heteroatom and carbon-carbon bond-forming methods. In certain embodiments, the present invention relates to copper-catalyzed methods of forming a carbon-sulfur bond between the sulfur atom of a thiol moiety and the activated carbon of an aryl, heteroaryl, or vinyl halide or sulfonate. In other embodiments, the present invention relates to copper(II)-catalyzed methods of forming a carbon-nitrogen bond between the nitrogen atom of an amide and the activated carbon of an aryl, heteroaryl, or vinyl halide or sulfonate. In certain embodiments, the present invention relates to copper-catalyzed methods of forming a carbon-carbon bond between the carbon atom of cyanide ion and the activated carbon of an aryl, heteroaryl, or vinyl halide or sulfonate. In another embodiment, the present invention relates to a copper-catalyzed method of transforming an aryl, heteroaryl, or vinyl chloride or bromide into the corresponding aryl, heteroaryl, or vinyl iodide. Yet another embodiment of the present invention relates to a tandem method, which may be practiced in a single reaction vessel, wherein the first step of the method involves the copper-catalyzed formation of an aryl, heteroaryl, or vinyl iodide from the corresponding aryl, heteroaryl, or vinyl chloride or bromide; and the second step of the method involves the copper-catalyzed formation of an aryl, heteroaryl, or vinyl nitrile, amide or sulfide from the aryl, heteroaryl, or vinyl iodide formed in the first step.
摘要:
One aspect of the present invention relates to optionally substituted halogenated benzyl halides and the like. These compounds are useful as halogenated benzyl ether-based protecting groups for a variety of functional groups. Another aspect of the present invention relates to use of said protecting groups in an orthogonal protecting group strategy for the synthesis of complex molecules that comprise a number of suitable functional groups. Another aspect of the present invention relates to saccharides bearing various arrays of protecting groups of the present invention. Another aspect of the present invention relates to a method of synthesizing an oligosaccharide or glycoconjugate, comprising the steps of: using a saccharide bearing at least one protecting group of the present invention to glycosylate a second molecule to give a product comprising said saccharide; and removing a protecting group of the present invention from said product.
摘要:
The present invention relates to a process for the preparation of N-aryl amine and N-aryl amide compounds. Generally, the process of the present invention involves reacting a compound having a primary or secondary amino or amido group with an arylating compound, in the presence of a weak base and a transition metal catalyst, under reaction conditions effective to form an N-aryl amine or N-aryl amide compound, the transition metal catalyst comprising a Group 8 metal, e.g., Ni, Pd, or Pt, and at least one carbene-containing ligand. Typically, the transition metal catalyst is formed in a preceding step from the conjugate acid form of the carbene ligand, a stoichiometric amount of a strong base, and a Group 8 metal atom or ion.
摘要:
One aspect of the present invention relates to novel, electron-rich bidentate ligands for transition metals. A second aspect of the present invention relates to the use of catalysts comprising these ligands in transition metal-catalyzed carbon-heteroatom and carbon-carbon bond-forming reactions. The subject methods provide improvements in many features of the transition metal-catalyzed reactions, including the range of suitable substrates, reaction conditions, and efficiency.
摘要:
A method of preparing an arylamine compound includes reacting a metal amide comprising a metal selected from the group consisting of tin, boron, zinc, magnesium, indium and silicon, with an aromatic compound comprising an activated substituent in the presence of a transition metal catalyst to form an arylamine. The method is useful in preparing mixtures of arylamines for use in screening for pharmaceutical and biological activity and in preparing poly(anilines).
摘要:
A process is provided whereby organic carbonyl substrates, including esters, ketones and amides, are reduced in a reaction with a silane reducing reagent and a catalyst. Effective catalysts broadly include those which consist of a group 4, 5 or 6 metal which either: a) is in less than its maximum oxidation state or is capable of being converted to a complex in less than its maximum oxidation state; and/or is a group 4, 5 or 6 metal hydride. Exemplary catalysts include titanium-containing catalysts such as (bis trimethylphosphine) titanocene, trimethyl phosphine adduct of a (hydrido) silyl complex of titanocene, titanocene dichloride and titanocene monochloride.