Methyl propionate, reaction with

As another example of novel catalysis employing montmorillonite, the clay was found to show excellent catalytic activity for the addition reaction of trimethylsilyl ketene acetal to a, -acetylenic esters (ynoates), which contrasted strikingly with the reactions induced by a homogeneous acid catalyst, trimethylsilyl triflate (TMSOTf), as well as the addition reactions of lithium enolates with ynoates [Eq. (17)] (89). Table XXIII summarizes the results of the reactions of the silicon and lithium enolates of methyl propionate (21) with ynoates (22a-c). Except for the reaction of 22c, ferric ion-exchanged montmorillonite (Fe-Mont), which is more acidic than Al-Mont, catalyzed exclusive 1,2-additions of trimethylsilyl ketene acetal to 22a and 22b to give 23 in... 

The high syn stereoselectivity attained in zirconium enolate aldol reactions has proved useful in complex natural product synthesis. The zirconium-mediated aldol reaction of the chiral ethyl ketone (9) with a chiral aldehyde has been used by Masamune et al. to give selectively adduct (10), which was further elaborated into the ansa chain of rifamycin S (equation 1). Good enolate diastereofacial selectivity is also obtained here and leads to a predominance of one of the two possible syn adducts. A zirconium enolate aldol reaction also features in the Deslongchamps formal total synthesis of erythromycin A, where the di(cyclopentadienyl)chiorozirconium enolate from methyl propionate adds with high levels of Cram selectivity to the chiral aldehyde (11) to give the syn adduct (12 equation 2). A further example is... 

The reaction was also tested over a V-P oxide catalyst with a P/V atomic ratio of 1.06 consisting of (VO)2P207 at a temperature of 320 °C and a methyl propionate/HCHO molar ratio of 2.0, using methylal as the source of HCHO. The yields of methyl methacrylate, acrylic acid, propionic acid reach 25, 6, and 20 mol%, respectively, based on the charged HCHO the sum of the yields of methyl methacrylate and methacrylic acid reaches 31 mol%. By the combination of Si with the V phosphate, the yield of methyl methacrylate is markedly improved. For example, over the VSi8P2,g catalyst, the yields of methyl methacrylate, methacrylic acid, and propionic acid reach 42, 6, and 20 mol%, respectively, based on the charged HCHO the sum of yields of methyl methacrylate and methacrylic acid reaches 48 mol% based on HCHO. The yield of methyl methacrylate increases as the methyl propionate/HCHO molar ratio is increased, for example, with the molar ratio of 4.0, the sum of yields of methyl methacrylate and methacrylic acid reaches 68 mol% based on the charged HCHO. As for the selectivity, the selectivity based on HCHO increases as the methyl propionate/HCHO ratio is increased, while the selectivity based on methyl propionate decreases. With a methyl propionate/HCHO molar ratio of 4.0, the selectivity based on HCHO is 100 mol%. On the other hand, when the molar ratio is 1.2, the selectivity based on methyl propionate becomes 100 mol%. 

One variation of the 1,4-dihydropyridine synthesis uses acetylene derivatives in place of P-ketoesters. Chennant and Eisner reported on the reaction between 2 equiv of methyl propionate 182 with aromatic aldehydes such as 183 and ammonium acetate in acetic acid to produce a series of dihydropyridine derivatives 184 in good yield. Unfortunately, differentially substituted acetylene derivatives and alkyl or nitrosubstituted aromatic aldehydes gave little to no yield of the desired 1,4-diydropyridine derivatives under the reported conditions. However, this method remains the best way to prepare of 2,6-unsubsitituted 1,4-dihydropyridines. 

The reaction of methyl propionate and formaldehyde in the gas phase proceeds with reasonable selectivity to MMA and MAA (ca 90%), but with conversions of only 30%. A variety of catalysts such as V—Sb on siUca-alumina (109), P—Zr, Al, boron oxide (110), and supported Fe—P (111) have been used. Methjial (dimethoxymethane) or methanol itself may be used in place of formaldehyde and often result in improved yields. Methyl propionate may be prepared in excellent yield by the reaction of ethylene and carbon monoxide in methanol over a mthenium acetylacetonate catalyst or by utilizing a palladium—phosphine ligand catalyst (112,113). 

Methylphenol is converted to 6-/ f2 -butyl-2-methylphenol [2219-82-1] by alkylation with isobutylene under aluminum catalysis. A number of phenoHc anti-oxidants used to stabilize mbber and plastics against thermal oxidative degradation are based on this compound. The condensation of 6-/ f2 -butyl-2-methylphenol with formaldehyde yields 4,4 -methylenebis(2-methyl-6-/ f2 butylphenol) [96-65-17, reaction with sulfur dichloride yields 4,4 -thiobis(2-methyl-6-/ f2 butylphenol) [96-66-2] and reaction with methyl acrylate under base catalysis yields the corresponding hydrocinnamate. Transesterification of the hydrocinnamate with triethylene glycol yields triethylene glycol-bis[3-(3-/ f2 -butyl-5-methyl-4-hydroxyphenyl)propionate] [36443-68-2] (39). 2-Methylphenol is also a component of cresyHc acids, blends of phenol, cresols, and xylenols. CresyHc acids are used as solvents in a number of coating appHcations (see Table 3). 

A mixture of B g (0.0356 mol) of p-(2.2-dichlorocyclopropyl)phenol, 11.2 g (0.2B mol) of sodium hydroxide pellets, 11 g of chloroform and 350 ml of acetone was prepared at 0°C. The cooling bath was removed, the mixture stirred for a minute and then heated on a steam bath to reflux temperature. The reaction mixture was stirred at reflux for three hours and then concentrated in vacuo. The residual gum was partitioned between dilute hydrochloric acid and ether, and the ether layer was separated, dried and concentrated in vacuo. The residual oil (14 g) was partitioned between dilute aqueous sodium bicarbonate and ether. The sodium bicarbonate solution was acidified with concentrated hydrochloric acid and extracted with ether. The ether solution was dried over anhydrous sodium sulfate and concentrated. The residue (9.5 g of yellow oil) was crystallized twice from hexane to give 6.0 g of 2-[p-(2,2-dlchlorocyclopropyDphenoxyl -2-methyl propionic acid in theformof apalecream[Pg.347]

To set the stage for the crucial aza-Robinson annulation, a reaction in which the nucleophilic character of the newly introduced thiolactam function is expected to play an important role, it is necessary to manipulate the methyl propionate side chain in 19. To this end, alkaline hydrolysis of the methyl ester in 19, followed by treatment of the resulting carboxylic acid with isobutyl chlorofor-mate, provides a mixed anhydride. The latter substance is a reactive acylating agent that combines smoothly with diazomethane to give diazo ketone 12 (77 % overall yield from 19). 

The derivative 90 was obtained by condensation of the purpurin-18-A-hexylimide-17-propionic acid with aminolactose heptaacetate in the presence of benzotriazol-l-yloxy-tris(dimethylamino)phosphonium hexafluorophosphate (BOP) followed by the deacetylation procedure. The lactose-photosensitiser conjugate linked by an ethylene moiety was also prepared by following a similar approach. The purpurin-18-methyl ester 81 was converted into /V-(3-iodobenzyl)/ /evo-purpurin-18-7V-hexylimide-17-propionic ester by hydrogenation over Pd/C followed by reaction with 3-iodo-benzylamine. Afterwards, the propargyllactose heptaacetate reacted with A-(3-iodobenzyl)rMeio-purpurin-18-A-hexylimide-l 7-propionic ester in the presence of tris(dibenzylidieneacetone)dipalladium(0) (Pd2-dba3) which, after deacetylation conditions, afforded the derivative 89 (Fig. 9).68... 

In contrast to these transformations, Michael additions of simple enolates to acceptor-substituted dienes often yield mixtures of 1,4- and 1,6-addition products27-30. For example, a 70 30 mixture of 1,4- and 1,6-adducts was isolated from the reaction of the lithium enolate of methyl propionate with methyl sorbate30. This problem can be solved by using the corresponding silyl ketene acetal in the presence of clay montmorillonite as acidic promoter under these conditions, almost exclusive formation of the 1,4-addition product (syn/anti mixture) was observed (equation ll)30. Highly regioselective 1,4-additions... 

Deprotonation of 3,3-bis(l-methylimidazol-2-yl)methane (41) with nBuLi at the bridging carbon atom and subsequent reaction with methyl bromoacetate gives methyl 3,3-bis(l-methylimidazol-2-yl) propionate bmipme (42) in high yields. Saponification of bmipme with aqueous NaOH gives bis-3,3-(l-methylimidazol-2-yl)propionate (bmip)... 

Various nitro compounds have been condensed with carbonyl compounds in reactions catalyzed by alkaline earth metal oxides and hydroxides 145). It was found that the reactivities of the nitro compounds were in the order nitro-ethane > nitromethane > 2-nitropropane, and those of carbonyl compounds were propionaldehyde > isobutyraldehyde > pivalaldehyde > acetone > benzaldehyde > methyl propionate. Among the catalysts examined, MgO, CaO, Ba(OH)2, and Sr(OH)2, exhibited high activity for nitroaldol reaction of nitromethane with propionaldehyde. In reactions with these catalysts, the yields were between 60% (for MgO) and 26% (for Sr(OH)2) at 313 K after 1 h in a batch reactor. On Mg(OH)2, Ca(OH)2, and BaO, the yields were in the range of 3.8% (for BaO) and 17.5% (for Mg(OH)2). Investigation of the influence of the pre-treatment... 

Few reports describe reactions of substituents at the benzene ring of benzotriazoles. The facile deprotonation of the methyl group in N-Boc-7-methyl-1-aminobenzotriazole (403) with butyllithium followed by reactions with electrophiles gives substituted products (404) (Scheme 78). The electrophile can be an alkyl halide, an aldehyde or a ketone, and the Boc group is removed by brief exposure to CF3CO2H in CH2CI2 <93TL6935>. 1-Acetylbenzotriazole (405) is hydrolyzed to form 3-(177-5-hydroxybenzotriazol-6-yl)propionic acid (406), which is then converted (Scheme 79) to... 

Table 1 summarizes the results of the reactions of ynoates (2a-c) with a silicon enolate (silyl ketene acetal) and a lithium enolate of methyl propionate (Eq. 1). Except for the reaction of 2c, Fe-Mont catalyzed exclusive 1,2-addition of silyl ketene acetal to 2a and 2b to give an adduct of 3 in high yields. However, even trimethyl silyl trifluoromethanesulfonate (TMSOTf), a generally applied homogeneous strong acid, failed to effect the addition reaction. 

The polar effect was at first invoked to explain various directive effects observed in aliphatic systems. Methyl radicals attack propionic acid preferentially at the a-position, ka/kp = 7.8 (per hydrogen), whereas chlorine " prefers to attack at the /3-position, ka/kp = 0.03 (per hydrogen). In an investigation of f-butyl derivatives, a semiquanti-tative relationship was observed between the relative reactivity and the polar effect of the substituents, as evidenced by the pK, of the corresponding acid. In the case of meta- and / ara-substituted toluenes, it has been observed that a very small directive effect exists for some atoms or radicals. When treated by the Hammett relation it is observed that p = —0.1 for H , CeHs , P-CH3C6H4 and CHs . On the contrary, numerous radicals with an appreciable electron affinity show a pronounced polar effect in the reaction with the toluenes. Compilation of Hammett reaction constants and the type of substituent... 

Other alkali/alkaline earth metal iodides either cleave esters less efficiently or form insoluble carboxylate salts and are therefore not as effective as Lil. Addition of Li and l" compounds capable of forming Lil under reaction conditions works as well as initially charging Lil (Table IV). The acetaldehyde producing step. Equation 17, is carried out with the cobalt-based catalyst. Since the carboxylate half of the ester is not involved with the cobalt center, any methyl ester which can be cleaved by Lil should also show activity. We have found that methyl isobutyrate, dimethyl malonate, methyl propionate, and dimethyl succinate yield acetaldehyde and the corresponding carboxylic acids in high yield under the same conditions utilized with methyl acetate. 

Fig. 11. Effect of NaBr concentration of modifying solution on amount of adsorbed TA or NaBr and enantioface-differentialing ability of TA-NaBr-MRNiA ( ) TA ( ) OY (O) Br. Catalyst RNiA (TA) (RNi pretreated with % TA at pH 3.2 and 100 C for I hr). Modifying condition TA (1%) + NaBr, pH 5.0, 0°C. Reaction conditions MAA (11.5 ml), methyl propionate (23 ml), AcOH (0.2 ml), 100 C, 110-130 kg/cm2.

If ethylene is present during the carbonylation of methanol catalyzed by IrCl4, once again with Mel as promoter, methyl propionate is formed.416 The reaction depends on the presence of iridium hydride species in solution, and a rhodium analogue of the reaction exists. The full details of the mechanism are not known but the basic steps are shown in Scheme 34. The intermediates are all believed to be complexes of iridium(IIl). 

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