Methyl cinnamate, hydrogenation

By heterogeneous reaction of methyl cinnamate, the C=C double bond is selectively hydrogenated [26] and methyl 3-phenylpropionate is formed the ester function is not affected. 

In 1989, Isayama and Mukaiyama reported a related Co-catalyzed coupling reaction that employs a,b-unsaturated nitriles, amides, and esters with PhSiLb as a hydrogen source [9]. Cobalt-bis(diketonato) complex, Co(II)(dpm)2 [dpm = bis(dipivaloylmethanato)] (5mol%), exhibited high catalytic activity at 20 °C in the coupling of excess acrylonitrile and ben-zaldehyde to provide b-hydroxy nitrile 4 in 93% yield (syn anti = 50 50) (Scheme 5). N,N-Dimethylacrylamide and methyl cinnamate both reacted... 

Fig. 44.4 N MR-spectroscopic monitoring of the enantioselective hydrogenation of (Z)-N-acetylamino methyl cinnamate using [Rh((R,R)-DI PAM P) (COD)]BF4 as catalyst under stationary conditions (reaction conditions 0.01 mmol Rh-complex,...

Photochemical hydrogen abstraction reaction for the silylimine 161 give an o-quinodimethane intermediate 162 which could be trapped with dimethyl fumarate, dimethyl maleate, trans-methyl cinnamate, methyl acrylate, acrylonitrile (equation 94)... 

Methyl cinnamate was reduced quantitatively to methyl 3-phenylpropa-noate by hydrogen over colloidal palladium at room temperature and atmospheric pressure [7057] ethyl cinnamate was reduced to ethyl 3-phenyIpropa-noate over tris(triphenylphosphine)rhodium chloride in ethanol at 40-60° and 4-7 atm in 93% yield [55], and over copper chromite at 150° and 175 atm in 97% yield [420]. On the other hand, hydrogenation of ethyl cinnamate over... 

Methyl Cinnamate. Using lower temperature and pressure than those used by Falbe (5) (to avoid lactone formation) the selectivity of the reaction toward aldehydes and hydrogenated products was comparable with his. 

Cabaleiro and Johnson (1967) report that the addition of chlorine to -methyl cinnamate in chloroform or acetic acid is syn-selective, SS 0-75, in chloroform and acetic acid acetoxychloro derivatives are produced as well. Again, Dewar and Fahey (1964) argue that the normal course of addition of hydrogen halides onto olefins is a polar electrophilic process involving classical carbonium ions as intermediates and leading mostly but not exclusively to cis-adducts. A syn-preference was found in the additions of deuterium bromide to acenaphthylene, indene, and cis- and fraws-phenylpropene. In the case of indene, phenylpropene and methyl cinnamate, which are styrene analogs, concerted syn addition is symmetry-allowed (see bottom of p. 273). 

The ketone carbonyl can be replaced by a substituted carbon-carbon double bond as in the p methyl cinnamic esters shown in Eqn. 14.21,6 or by an a imino (Eqn. 14.22) or oximino group (Eqn. 14.23).62 Hydrogenation of these compounds gave the corresponding chiral materials with ee s ranging from 5-35%. 

Substrates for hydrogenation were methyl cinnamate (I), methyl-a-methyl cinnamate (II), methyl-p-methyl cinnamate (III), methyl-a-phenyl cinnamate (IV), dimethyl itaconate (V), dimethyl mesaconate (VI), and dimethyl citraconate (VII). Their structures and the names of the corresponding hydrogenation products are given in Table 1. 

Biemer et al. reported the enantioselective behaviors of a Pd catalysts supported on specially prepared silica gels, which have been precipitated from Na silicate wiA HCl in the presence of optically active alkaloids sulfates of quinine (Q), quinidine (Qd ), cinchonine (Cn), or cinchonidine (Cnd). These catalysts proved to be active in the asymmetric hydrogenation of 2-methyl-cinnamic acid (Scheme 3.1.) . 

When the ligand (5,5)-70 was used, methyl cinnamate (71) was converted to the corresponding aziridine (S,S)-72 in 63% yield with an ee of 94% , but the optimal conditions for the aziridination of the cinnamate esters cannot be reliably extrapolated to other acyclic olefins . Reductive ring opening of (S,S)-72 by transfer hydrogenation afforded the corresponding (/f)-methyl iV-(p-toluenesulphonyl)phenylalaninate [(R)-73] and established the absolute configuration of (S,5 )-72 . This latter reaction and other reactions of the... 

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