A facile and efficient synthesis of 2,2,2-trifluoroethyl 2-[(E)-N-phenylcinnamamido]-2-phenylacetates in trifluoroethanol via sequential Ugi four-component reaction/esterification
摘要:
We describe an efficient approach for the synthesis of N-substituted 2-alkenylamides in trifluoroethanol via an Ugi 4-component reaction in short reaction times. The use of a catalytic amount of sulfuric acid in trifluoroethanol gave the desired trifluoroethyl derivatives in good to high yields. (C) 2012 Elsevier Ltd. All rights reserved.
rhodium(I) by means of an RhI–OH complex, enables the conjugate transfer of nucleophilic silicon onto α,β-unsaturated acceptors. Pre- or in situ formed cationic rhodium(I)–binap complexescatalyze this novel carbon–silicon bond formation with exceptional enantiocontrol, 92 to >99% ee for cyclic carbonyl and carboxylcompounds as well as >99% ee for acyclic carboxylcompounds.
铑(I)催化的硅-硼键活化,即通过Rh I -OH络合物将硅从硼转变为铑(I),可以将亲核硅共轭转移到α,β上-不饱和受体。预制的或原位形成的阳离子铑(I)-联萘酚配合物可催化这种新型的碳-硅键形成,具有出色的对映体控制能力,环状羰基和羧基化合物的ee为92%至> 99%ee,无环羧基化合物的ee> 99%。
Chemo-enzymatic Synthesis of 6?-O-(3-Arylprop-2-enoyl) Derivatives of the Flavonol Glucoside Isoquercitrin
directly introduce these acyl moieties by an enzyme-catalyzed reaction of 2a with the corresponding activated esters. This new approach was based on the regioselective introduction of a methyl malonate residue at the CH2OH of the sugar moiety by catalysis with the protease subtilisin ( 22a). The mixed diester 22a was then subjected to chemoselective hydrolysis of the methoxycarbonyl function by another
Conjugate phosphination of cyclic and acyclic acceptors using Rh(I)–phosphine or Rh(I)–carbene complexes. Probing the mechanism with chirality at the silicon atom or the phosphorus atom of the Si–P reagent
作者:Verena T. Trepohl、Roland Fröhlich、Martin Oestreich
DOI:10.1016/j.tet.2009.04.038
日期:2009.8
The Rh(I)-catalyzed conjugate phosphinyl transfer from an Si–P reagent to an electron-deficient acceptor requires individual protocols for cyclic and acyclic α,β-unsaturatedcarbonyls and carboxyls. While 1,4-addition to cyclic acceptors is catalyzed by a Rh(I)–phosphine complex, a Rh(I)–carbene complex is needed to promote conjugate phosphination of acyclic acceptors. General procedures for both systems
A highly chemoselective and reactive μ‐oxo‐dinuclear iron(III) salen catalyst for transesterification was developed. The developed ironcomplexcatalyzed acylation of aliphatic amino alcohols with nearly perfect O‐selectivity, even when using activated esters, for which chemoselectivity is more difficult to control. In addition, O‐selective transesterification of aromatic amino alcohols was achieved
Correlation of the rates of solvolyses of cinnamyl chloride
作者:In Sun Koo、Sun Kyoung An、Kiyull Yang、Ikchoon Lee、T. William Bentley
DOI:10.1002/poc.550
日期:2002.11
constants (k) at 25 °C are reported for solvolyses of cinnamyl chloride (1) in binary mixtures of water with acetone, ethanol, methanol, methanol-d and 2,2,2-trifluoroethanol (TFE), and also in TFE–ethanol mixtures; product selectivities (S) are reported for aqueous ethanol and methanol: S = [ether product]/[alcohol product] × [water]/[alcohol solvent]. A good correlation observed between log k and the parameter