Malonic benzylidene

The synthesis of the right-wing sector, compound 4, commences with the prochiral diol 26 (see Scheme 4). The latter substance is known and can be conveniently prepared in two steps from diethyl malonate via C-allylation, followed by reduction of the two ethoxy-carbonyl functions. Exposure of 26 to benzaldehyde and a catalytic amount of camphorsulfonic acid (CSA) under dehydrating conditions accomplishes the simultaneous protection of both hydroxyl groups in the form of a benzylidene acetal (see intermediate 32, Scheme 4). Interestingly, when benzylidene acetal 32 is treated with lithium aluminum hydride and aluminum trichloride (1 4) in ether at 25 °C, a Lewis acid induced reduction takes place to give... 

Allylic chlorides can also be used as coupling partners, as shown by Lu and Liu [137]. In addition, the domino process could be used for the synthesis of benzylidene pyrrolidines, as shown for the reaction of 6/1-285 with benzylidene malonate... 

Dimethyl mesoxolate Propanedioic acid, oxo-, dimethyl ester (9) (3298-40-6) Dimethyl benzalmalonate Malonic add, benzylidene-, dimethyl ester (8) Propanedioic add, (phenylmethylene)-, dimethyl ester (9) (6626-84-2) Dimethyl sulfide Methyl suflide (8) Methane, thiobis- (9) (75-18-3)... 

Similar cyclopropanation reactions have been performed with benzylidene and alkyli-dene malonic esters. ... 

The activated Ba(OH)2 catalyst was successfully used for the Michael reactions of chalcone with active methylene compounds 290), as well as for the Michael reaction of other benzylidene derivatives of acetone, butanone, 3-methylbutanone, 4-methyl-2-pentanone, and 3,3-dimethylbutanone with ethyl acetoacetate and diethyl malonate. The reaction with diethyl malonate gave good yields of the Michael adduct (between 65 and 93%), whereas with ethyl acetoacetate various products were obtained, depending on temperature and amount of catalyst (Scheme 43) 291). Thus, by varying the reaction conditions, it was possible to obtain a single product with practically 100% selectivity, the yields being higher than those obtained with soluble catalysts, such as KOH, NaOH, or piperidine. 

The first asymmetric iron-catalyzed conjugate addition was reported in 1977. Benzylidene malonate 56 with an ephedrine moiety as chiral auxiliary was converted with Grignard reagents such as nBuMgBr in the presence of catalytic amounts of various metal salts. The optically active phenylpropionic acid 57 was obtained with... 

Simple bis(oxazoline) ligands, especially azabis(oxazolines), can catalyse the addition of indoles to benzylidene malonates in up to 99% ee, provided that excess of the chiral ligand is avoided.166 The paradigm followed in many asymmetric catalytic reactions that an excess of the chiral ligand with respect to the metal should improve enantioselectivity because the background reaction catalysed by a free metal is suppressed, was shown not to be applicable here,166 which might call for revisiting some of the many copper(II)-bis(oxazoline)-catalysed processes known. Enantioselective additions of pyrroles and indoles to ,/9-unsaturated 2-acylimidazoles catalysed by the bis(oxazolinyl)pyridine-scandium(III) triflate complex have been accomplished.167... 

Ma and co-workers have reported the selective synthesis of pyrrolidine derivatives through a three-component reaction based on a conceptually related strategy (Scheme 8.29) [72], Beginning with the catalytic intermolecular carbopalladation of y-allenic malonate 57 in the presence of a base, they succeeded in intercepting the internal carbonucleophile 58 with an imine such as the N-benzylidene p-toluenesulfonamide 59. The attack of the newly formed heteronucleophile on the 7r-allyl palladium intermediate affords the functionalized pyrrolidine 60 with high... 

Mit 2-AIkennitrilen (z.B. Acrylnitril) in Gegenwart von Eisen(III)-chlorid133 bzw. aus Phosphor(V)-chlorid mit 3-Amino-2-alkcnnitriIcn [z.B. (a-Amino-benzyliden)-malon-saure-dinitril134 werden die folgenden Derivate erhalten ... 

In a series of papers Desimoni and Righetti [158-160] have now shown that the addition of salts such as lithium perchlorate and magnesium perchlorate not only accelerates the reaction, but also has a high influence on the ratio of ene and Diels-Alder products. Reaction of the benzylidene-1,3-diketone 2-156 with LiC104 at 25 °C for 3 days a 85 15 ratio of 2-157 and 2-158 in 70% yield and with Mg(C104)2 at 25 °C for 20 h a 7 93 ratio in 100% yield was obtained (Fig. 2-44). However, as expected the corresponding benzylidene-malonate gives the ene product exclusively under all conditions. 

On the basis of this palladium-mediated Michael addition cyclization process, a novel two-step synthetic entry into functionalized furan derivatives 67 has also been devised (Scheme 28). Substitution of benzylidene (or alkyli-dene) malonates for their ethoxymethylene analog (65) as activating olefins gave rise to the formation of the corresponding 2-ethoxy-4-arylidene tetrahy-drofurans 66. An in situ addition of potassium ferf-buloxidc induced a decar-boxylative elimination reaction which was followed by an isomerization of the exocyclic double bond. The entire process successively involved a conjugate addition, a palladium-catalyzed cyclization-coupling reaction, a base-induced eliminative decarboxylation, and finally, a double bond isomerization [73]. 

An eight-stage synthesis of 2-methylbenzomorphan (115) from benzal-dehyde via diethyl benzylidene malonate (110) in 19% overall yield has been reported<52) (Scheme 4,17). The amino radical precursor, N-chloramine (111),... 

Rasappan R, Hager M et al (2006) Highly enantioselective michael additions of indole to benzylidene malonate using simple bis(oxazoline) ligands importance of metal/ligand ratio. Org Lett 8 6099-6102... 

Enantioselective Michael Additions. Amine 1 has also been used as an effective ligand for enantioselective Michael reactions of ketone lithium enolate donors with various benzylidene acceptors. As representative examples, the lithium enolates of aryl methyl ketones were reacted with dimethyl benzylidene-malonate in the presence of 1 (eq 9). The lithium enolate was generated from the corresponding ketone by treatment with hex-amethyldisilazide in the presence of lithium bromide in toluene. The resulting enolate was then exposed to 1 and allowed to stir for 30 min to form the desired ternary complex. After addition of the benzylidene acceptor, the desired products were isolated in acceptable yields and with high % ee. 

The benzylidene complex [Ru=CHPh(Cl)(Bp)(CgHi4)(PCy3)], octahedral, exhibits an agostic Ru H-C interaction and displays catalytic activity for the ring closing metathesis of diethyl-malonate in the presence of CuCl as a cocatalyst in refluxing toluene.27 The crystal structure of the octahedral hydrido compound [Rn(Bp)(H)(C0)(AsPh3)2]-H20 has been reported.28... 

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