Morita-Baylis-Hillman carbonates reaction

The Morita-Baylis-Hillman (MBH) reaction is the formation of a-methylene-/ -hydroxycarbonyl compounds X by addition of aldehydes IX to a,/ -unsaturated carbonyl compounds VIII, for example vinyl ketones, acrylonitriles or acrylic esters (Scheme 6.58) [143-148]. For the reaction to occur the presence of catalytically active nucleophiles ( Nu , Scheme 6.58) is required. It is now commonly accepted that the MBH reaction is initiated by addition of the catalytically active nucleophile to the enone/enoate VIII. The resulting enolate adds to the aldehyde IX, establishing the new stereogenic center at the aldehydic carbonyl carbon atom. Formation of the product X is completed by proton transfer from the a-position of the carbonyl moiety to the alcoholate oxygen atom with concomitant elimination of the nucleophile. Thus Nu is available for the next catalytic cycle. 

Chen and coworkers published a formal [3 + 3]-type reaction to give highly substituted cyclohexenes 8. This domino process consists of an allylic-allylic alkylation of an a,a-dicyanoalkene derived from 1-indanone and Morita-Baylis-Hillman carbonates, following an intramolecular Michael addition, by employing dual orga-nocatalysis of commercially available modified cinchona alkaloid (DHQD)2AQN If (hydroquinidine (anthraquinone-l,4-diyl) diether) and (S)-BINOL. The cyclic adducts... 

Chen and coworkers employed the cinchona alkaloid-derived catalyst 26 to direct Mannich additions of 3-methyloxindole 24 to the A-tosylimine 25 to afford the all-carbon quaternary center of oxindole 27 with good enantioselectivity (84% ee) [22]. The outcome of this Mannich reaction is notable in that it provided very good selectivity for the anti diastereomer (anti/syn 94 6). The mechanism of asymmetric induction has been suggested to involve a hydrogen bonding network between the cinchona alkaloid 26, the oxindole enolate of 24, and the imine electrophile 25 (Scheme 7). Asymmetric allylic alkylation of oxindoles with Morita-Baylis-Hillman carbonates has been reported by the same group [23]. 

Morita-Baylis-Hillman carbonates undergo an hydrolysis in the presence of the asymmetric organocatalyst, hydroquinidine[anthraquinone-l,4-diyl] diether, and Cap2 in aqueous iV,iV-dimethylacetamide, yielding the allylic alcohol Tracer studies using showed that water is the nucleophile in the hydrolysis reaction. It is... 

A phosphane-catalyzed [4 - -1] annulation between nitroalkenes and Morita-Baylis-Hillman carbonates was performed by He and co-workers. " The authors claimed the in situ formation of an allylic phosphorus ylide as an active intermediate. Allenoates and enones were able to form cyclopentenes via two cycloaddition reactions they underwent a [3 -F 2] or a [2 -F 4] process in the presence of catalytic phosphines or amines, respectively (Scheme 15). To explain such a different reactivity, Huang, Lankau and Yu, carried out M06-2X/6-31- -G calculations to study the role of ylide intermediates. ... 

The Morita-Baylis-Hillman (MBH) reaction is described as the coupling between the a-position of an activated double bond and an sp electrophilic carbon (typically an aldehyde, but also an imine) using an appropriate catalyst, normally Lewis bases [21]. Shi and coworkers showed that imidazole and proline formed an efficient co-catalytic system for carrying out the MBH reaction, but with low ee [22]. 

Recently, 4 was reported to be an excellent catalyst for the enantioselective substitution of Morita-Baylis-Hillman carbonates with allylamines [21]. Only carbonates with an aromatic group gave the desired enantioenriched N-allyl-P-amino-methylene esters (Scheme 6.6). Ring-closing metathesis of the products of the allylation reaction was shown to result in chiral 2,5-dihydropyroles of importance as starting materials for the synthesis of products of biological and medical interest. 

The Morita-Baylis-Hillman (MBH) reaction is a powerful carbon-carbon bondforming reaction that has found widespread application in organic synthesis. In 2005, Miller and Hong independently reported the highly enantioselective intramolecular MBH reaction. The Miller group applied a combination of (S)-pipecohc acid 79 and N-methylimidazole to catalyze the cychzation of heptenal derivatives 80 in aqueous THF (Scheme 36.21a) [27a]. In contrast, Hong and coworkers used simple L-proline and imidazole as the catalysts (Scheme 36.21b) [27b]. 

MBH (Morita-Baylis-Hillman) carbonates 124 MBH (Morita-Baylis-Hillman) reactions 131, 208, 250, 251, 261... 

Morita-Baylis-Hillman (MBH) carbonates 124 Morita-Baylis-Hillman (MBH) reactions 131... 

The phosphine (127)-catalysed asymmetric 4 +1-cycloaddition reaction of Morita-Baylis-Hillman carbonates with dicyano-2-methylenebut-3-enoates formed highly functionalized cyclopentenes in high yields and excellent ee% The [RuCl(CO)2]2-catalysed 4 + 1-cycloaddition reaction of alkenyl propargyl acetates, RCH(OAc)C=CC(Me)=CH2, with CO in CH2CI2 produced highly functionalized cyclopentenones in high yields (96%). The chiral copper/Tol-BINAP complex... 

Carbon-carbon bond forming reactions constitute die core of organic synthesis, and novel, efficient methods are always desirable. One such reaction that has attracted much attention in recent days is the Morita-Baylis-Hillman (MBH) reaction the reaction of activated olefins with reactive carbonyls or imines in the presence of a catalytic amount of trialkyl(aryl)phosphine or amine (i-i). Of all the amines tested, 1,4-diazabicyclo[2.2.2]octane (Dabco) has been found to be superior (Scheme 1). This reaction, which provides multifunctional molecules has been accommodated in certain undergraduate curriculum (4), and does not demand any sophisticated techniques or instrumentation. 

The asymmetric allylic substitution reaction of Morita-Baylis-Hillman carbonates (226) with diphenyl phosphite in the presence of chiral multifunctional thiourea-phosphine catalyst (228) provided allylic phosphites (227) in high yields and with excellent enantioselectivities (Scheme 76). 

Also known as Morita-Baylis-Hillman reaction, and occasionally known as Rauhut-Currier reaction. It is a carbon—carbon bond-forming transformation of an electron-poor alkene with a carbon electrophile. Electron-poor alkenes include acrylic esters, acrylonitriles, vinyl ketones, vinyl sulfones, and acroleins. On the other hand, carbon electrophiles may be aldehydes, a-alkoxycarbonyl ketones, aldimines, and Michael acceptors. 

The Morita-Baylis-Hillman reaction is, in general, a carbon-carbon bondforming reaction of an a,(3-unsaturated compound with an aldehyde mediated by an organic nucleophilic base resulting in the formation of an allylic alcohol. Morita reported the use of a phosphine as catalyst and Baylis and Hillman used a tertiary amine. Variation of the electrophile to electron-deficient alkenes in a Michael-Michael elimination sequence leads to homo- and heterodimerisation and is known as the Rauhut-Currier reaction. The electrophilic aldehyde could be substituted by an imine or derivative in the aza-Morita-Baylis-Hillman reaction. Recently, there has been an increase in the use of this reaction for the construction of many different targets using many different amine derived catalysts. Scheme 2.2 shows a general view of this reaction and the accepted mechanism. ... 

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