以森田-贝里斯-希尔曼(MBH)碳酸酯为原料合成多取代1,4-二氢喹啉类衍生物

以森田-贝里斯-希尔曼(MBH)碳酸酯和活泼亚甲基类化合物为原料,在叔胺的催化下,经历两次亲核取代反应得到关键叠氮中间体,再与三苯基膦作用经连续的Staudinger反应、分子内aza-Wittig反应及异构化等,在温和的反应条件下合成了17个新的多取代1,4-二氢喹啉类衍生物.中间体及目标化合物均为新化合物,其结构均...     

Bifunctional catalysis of Morita-Baylis-Hillman (MBH) reaction with chiral primary-tertiary diamine: A non-typical MBH catalytic pathway

A simple primary-tertiary diamine has been explored as a novel catalyst for the Morita-Baylis-Hillman reaction of MVK and aryl aldehydes, and moderate to good chemical yields were obtained. Detailed mechanism study indicated that the diamine acted as a bifunctional cooperation catalyst via a bicyclic enamino-quaternary ammonium intermediate.     

An efficient,recoverable fluorous organocatalyst for accelerating the DABCO-promoted Morita-Baylis-Hillman reaction

A convenient method for Morita-Baylis-Hillman reaction of arylaldehydes with methyl acrylate has been developed by using fluorous-tag organocatalyst 1-[4-(perfluorooctyl)phenyl]-3-phenylthiourea and DABCO at room temperature.The fiuorous, organocatalyst could be recovered from the reaction mixture by fiuorous solid-phase extraction(F-SPE) with excellent purity for direct reuse.     

Asymmetric Morita-Baylis-Hillman reactions of 2-cyclohexen-1-one catalyzed by chiral biaryl-based bis(thiourea) organocatalysts

Newly-developed bis(thiourea) 1d was found to be an efficient organocatalyst for the Morita-Baylis-Hillman reaction. High enantioselectivities were obtained in the reaction of 2-cyclohexen-1-one with both aromatic aldehydes (up to 84% ee) and aliphatic aldehydes (up to 96% ee).     

ZrCl4-catalyzed X-C/C-C bond formation for the geometric selective synthesis of (E)-β-iodo aza Morita-Baylis-Hillman (MBH) adducts

A geometric selective synthesis of (E)-β-iodo and β-alkyl vinyl ketones (MBH amino adducts) has been developed through a three-component Mannich-type reaction. The reaction was conveniently conducted by generating 3-iodo allenolate intermediates via the α,β-unsaturated addition of TMS-I to 3-butyn-2-one followed by a carbonyl addition onto N-aryl imines in the presence of ZrCl₄ catalyst. The resulting β-iodo allylic amines can be readily converted into β-alkyl Morita-Baylis-Hillman adducts by performing Suzuki and Kumada cross-couplings.     

The enantioselective intramolecular Morita-Baylis-Hillman reaction catalyzed by amino acid-derived phosphinothiourea

A series of chiral bifunctional phosphinothioureas derived from l-amino acids have been developed to promote the enantioselective intramolecular Morita-Baylis-Hillman reaction. The process afforded the cyclic hydroxyl enones with up to 84% ee and good yields under mild conditions.     

A catalytic asymmetric anti-selective nitroaldol reaction with a neodymium-sodium heterobimetallic complex

A catalytic asymmetric anti-selective nitroaldol reaction with a neodymium-sodium heterobimetallic catalyst is described. A readily accessible amide ligand works efficiently as a chiral platform for the Nd/Na heterobimetallic catalyst in the reaction of various aldehydes and nitroethane, affording anti-1,2-nitro alkanols in good diastereo- and enantioselectivity.     

1-Methylimidazole 3-N-oxide as a new promoter for the Morita-Baylis-Hillman reaction

The Morita-Baylis-Hillman reaction of aldehydes with α,β-unsaturated ketones can be affected by the Lewis bases. We have found that 1-methylimidazole 3-N-oxide promoted the Morita-Baylis-Hillman reaction of various activated aldehyde compounds in non-solvent system. This is a mild reaction condition and requires no special equipment to give the Morita-Baylis-Hillman adducts.     

Enantioselective aldol reaction of silyl ketene acetals promoted by a Lewis base-activated Lewis acid catalyst

The enantioselective aldol reaction of a silyl ketene acetal was promoted by chiral phosphine oxide-activated tetrachlorosilane to afford the corresponding adduct in high yield with moderate enantioselectivity.     

Organocatalytic (1+4)-Annulations of MBH Adducts with Electron-Deficient Systems

Benefited from the rapid development of MBH reaction, the reaction of MBH adducts have been established as the most synthetically useful transformations. However, compared with the well-established allylic alkylations and (3+2)-annulations, the (1+4)-annulations of MBH adducts have not developed rapidly until recently. As a helpful complement to the (3+2)-annulations of MBH adducts, the (1+4)-annulations of MBH adducts opens a robust access to structurally diverse five-membered carbo- and heterocycles. This paper summarizes recent advances in organocatalytic (1+4)-annulations using MBH adducts as 1 C-synthons for the construction of functionalized five-membered carbo- and heterocycles.     

A substrate controlled, very highly diastereoselective Morita-Baylis-Hillman reaction: a remote activation of the diastereofacial selectivity in the synthesis of C-3-branched deoxysugars

The Morita-Baylis-Hillman (MBH) reaction of p-nitrobenzaldehyde with C (6) acyl protected enuloside 1 in the presence of TiCl₄/TBAI yielded highly diastereoenriched C-3-branched deoxysugar derivative or MBH adduct 1′a in high yield, while reactions of unprotected enuloside 2a and C (6) alkyl protected enulosides 2d-e with p-nitrobenzaldehyde under the same conditions afforded the adducts 2′a and 2′d-e, respectively, in low yield with moderate selectivity. Several representative aromatic and aliphatic aldehydes were selected to undergo MBH reaction with 1 to give their respective adducts in very good yield with a very high diastereoselectivity. A plausible mechanism based on the assumption of a Zimmerman-Traxler-type transition state was proposed to explain the excellent selectivity observed with adducts derived from 1. The synthetic application of these adducts were shown by their stereoselective reduction to corresponding threo isomers in very good yield.     

An efficient and simple Morita-Baylis-Hillman reaction based on the N-methylpyrrolidine-Ba(OH)2 catalytic system

By using of precise catalytic amount of N-methylpyrrolidine (5 mol %) and Ba(OH)₂ (1.5 mol %) in H₂O/CH₃OH 5/1 or CH₃OH/CH₂Cl₂ 3/1 solvent mixtures at T=0 °C a Morita-Baylis-Hillman derivatives could be obtained in good to excellent yield from 2-cyclopenten-1-one, 2-cyclohexen-1-one and formaldehyde and diverse aryl aldehydes after suitable reaction time.     

A novel approach to Morita-Baylis-Hillman (MBH) lactones via the Lewis acid-promoted couplings of α,β-unsaturated lactone with aldehydes

The Morita-Baylis-Hillman (MBH)-type reaction of α,β unsaturated δ-lactone with various aldehydes has been achieved without the direct use of a Lewis base. The new MBH process can be conveniently carried out by the slow addition of the diethylaluminum iodide into the solution of lactone and aldehyde in dichloromethane at 0°C. Modest to good yields were obtained (50-65%) for eight examples.     

DFT study of the asymmetric nitroaldol (Henry) reaction catalyzed by a dinuclear Zn complex

We report the mechanism of asymmetric nitroaldol (Henry) reaction catalyzed by a dinuclear Zn complex using density functional theory. The experimentally proposed catalytic cycle is validated, in which the first step is the deprotonation of nitromethane by the ethyl anion of the catalyst, subsequently a C? C bond formation step, and then the protonation of the resulting alkoxide. Three mechanistic scenarios (differing in binding modes) have been considered for the C? C bond formation step. The origin of the enantioselectivity is discussed. Our calculations supported that the S configurations are the major products, which is in agreement with the experimental observations. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010     

Asymmetric ring opening reaction of oxabenzonorbornadienes with amines promoted by iridium/NMDPP complex

As an efficient catalyst, the [Ir(COD)Cl]₂/NMDPP complex has been successfully applied to promote the asymmetric ring opening reaction of oxabenzonorbornadienes with various amines, which afforded the corresponding products in good yields (72–98%) with good enantioselectivities (80–90% ee).     

Catalytic application of dinuclear palladium(II) bis(thiosemicarbazone) complex in the Mizoroki-Heck reaction

A convenient synthesis of new square planar dinuclear palladium(II) terephthaldehyde bis(thiosemicarbazone) complex has been described. The compositions of the complex have been established by elemental analysis, spectral methods and single crystal X-ray crystallographic technique. The new complex acts as an active recyclable homogeneous catalyst for the Mizoroki-Heck reaction of electron deficient (activating) and electron rich (deactivating) aryl halides with various olefins under optimized conditions.     

Siloxyallenes revisited. A useful functional intermediate for the synthesis of (Z)-β-branched Morita-Baylis-Hillman type adducts and (Z)-chalcones

Siloxyallenes proved to be a useful functional intermediate in the preparation of (Z)-β-branched Morita-Baylis-Hillman type adducts by the reaction of aldehydes with silylacetylenes or siloxypropynes. Various (Z)-chalcones were stereoselectively synthesized from siloxypropynes via siloxyallenes.     

Study on the Heck reaction promoted by carbene adduct of cyclopalladated ferrocenylimine and the related reaction mechanism

Carbene adduct of cyclopalladated ferrocenylimine has been successfully applied to Heck reaction of various aryl bromides with olefins. On the basis of kinetic studies, in situ ¹³C NMR spectra investigations and Hg poisoning experiments, it was proposed that the Heck reaction catalyzed by carbene adduct of cyclopalladated ferrocenylimine proceeded through a classical Pd(0)/Pd(II) cycle and such palladacycle was only a reservoir of the catalytically active Pd(0) species.