Condensation, of benzaldehyde with

The acid catalyzed condensation of benzaldehydes with 2-acetyIpyridine provides access to hydroxy- or amino-indolizines (Scheme 58a) (71CB1629,71CB1645). A remarkable synthesis of fused pyrrolidines in which aldehydes also provide C-2 is exemplified in Scheme 58b... 

Claisen reaction is the condensation of benzaldehyde with aliphatic aldehydes and ketones containing a-hydrogen C6H5CHO -r CH3CHO C6H5CH=CH CHO -r HjO... 

The reactions of enamines with aldehydes (329,350) are noteworthy in that they provide a route to the monobenzylidene derivatives of five- to seven-membered eyclic ketones as well as a method for the formation of other a, 9-unsaturated carbonyl compounds, in fair to good yields. The condensation of benzaldehyde with enamines is also involved in the formation of 3,5-dibenzylpyridine from piperidine and benzaldehyde (191-193). 

Formal oxidation of pyrrolidine to the succinimide stage affords a series of compounds used as anticonvulsant agents for treatment of seizures in petit mal epilepsy. Knoevnagel condensation of benzaldehyde with ethyl cyanoacetate affords the unsaturated ester, 9. Conjugate addition of cyanide ion leads to the di-nitrile ester (10). Hydrolysis in mineral acid affords the succinic acid (11), presumably by decarboxylation of the intermediate tricarboxyllie acid. Lactamization with methylamine gives phensuximide (12). ... 

Lithium aluminum hydride, in reduction of 3-ethoxy-2-cyclohexenone to 2-cyclohexenone, 40, 14 Lithium ethoxide in condensation of benzaldehyde with tripbenylcin-namylphosphonium chloride to form 1,4-diphenyl-l, 3-butadiene,... 

Analogously, the silylated / -hydroxyallylsilane 655 condenses with excess dihy-drocinnamaldehyde in the presence of TMSOTf 20 at -78 °C to afford, via 656, the dihydropyran 657 in 82% yield [191] (Scheme 5.58). Condensation of benzaldehyde with methoxytrimethylsilane 13 a and l-trimethylsilyl-2-butyne 658 in the presence of TMSOTf 20 in CH2CI2 affords the allenyl compound 659 in 97% yield and HMDSO 7 [192]. 

Sadvilkar et al. (1995) have studied condensation of benzaldehydes with acetophenones (Claisen-Schmidt reaction) in an aqueous medium, containing sodium butylmonoglycol sulphate and sodium salts of aromaticsulphonic acids as hydrotropes. A substantial improvement in the rate of reaction was realized, while product recovery was facilitated. 

For example gold(III) complexes with /3-diketonates or alkylsiloxydes, are likewise employed as precursors for CVD. 73,177 Another promising result in the field of homogeneous catalysis is the discovery that gold(III) alkoxo complexes promoted the condensation of benzaldehyde with compounds containing an active methylene group.1775... 

Condensation of benzaldehydes with benzotriazole in the presence of thionyl chloride readily gives a,a-/fe(benzo-triazol-l-yl)toluenes 727 that can be considered as l,l -gm-dicarbanion equivalents. Thus, treatment of derivatives 727 with ketones and lithium metal suspended in THF at — 78 °C generates substituted propylene glycols 728 (Equation 18) <1998TL2289>. 

The aldol condensation of benzaldehyde with the thioacetamide carbanion (RCHCSNRV), derived from the desilylation of the silyl-thioether with tetra-/i-buty-lammonium fluoride, is stereoselective at—80°C producing the erythro isomer of the p-hydroxy thioamide preferentially (Scheme 6.18, R = Me, erythro threo 95 5) via a conformationally mobile intermediate. However, when R is bulky, a greater amount of the threo isomer is formed. Predictably, as the reaction temperature is raised, so the stereoselectively decreases. This procedure contrasts with the corresponding condensation catalysed by titanium salts, where the complexed intermediate produces the threo isomer [47, 48],... 

Recently, cross-aldol condensation of benzaldehyde with n-heptaldehyde to give jasminaldehyde (Scheme 13) has been reported a mesoporous molecular sieve Al-MCM-41 with supported MgO was the catalyst. The reactions were carried out in a stirred autoclave reactor with a molar benzaldehyde/heptanal ratio of 10 at 373-448 K (236). The results show that Al-MCM-41 is catalytically active, and its activity is significantly increased by the deposition of MgO (Table V). Increasing the amount of deposited MgO on Al-MCM-41 decreases the surface area but enhances the catalyst basicity. The basicity is well correlated with the catalytic activity, although the selectivity to jasminaldehyde is not the selectivity is essentially independent of temperature, pressure, time of the reaction, and conversion. 

Cross-aldol Condensation of Benzaldehyde with Heptanal on Basic Catalysts (236)... 

A number of routes are available for the synthesis of 2,2 -bipyridines where one of the pyridine rings is built up from simpler entities. For example, condensation of 2-(aminomethyl)pyridine (31) with acetaldehyde or acetylene over a silicon-alumina catalyst at 450°C gives 2,2 -bipyridine, ° whereas 2-cyanopyridine reacts with acetylene at 120°C in the presence of a cobalt catalyst to afford 2,2 -bipyridine in 95% yield.2-Acetylpyridine with acrolein and ammonia gives 2,2 -bipyridine in the presence of dehydrating and dehydrogenating catalysts, and related condensations afford substituted 2,2 -bipyridines. ° In a similar vein, condensation of benzaldehyde with 2 mol of 2-acetylpyridine in the presence of ammonia at 250°C affords 2,6-di(2-pyridyl)-4-phenylpyridine, ° and related syntheses of substituted 2,2 6, 2"-terpyridines have been described. Likewise, formaldehyde with two moles of ethyl picolinoylacetate and ammonia, followed by oxidation of the product and hydrolysis and decarboxylation, affords a good... 

An exhaustive series of reports by Grigg et al. (28) outlined two basic methods for the generation of azomethine ylides proceeding via either a 1,2-prototropic shift, or by a decarboxylative approach (29). The decarboxylative route to azomethine ylides can be exemplified by the condensation of benzaldehyde with the cyclic amino acid tetrahydroisoquinoline (108) (30), in DMF at 120 °C, to generate the intermediate awfi-dipole 109, which underwent subsequent cycloaddition with N-methyl maleimide to furnish a 1 1 endo/exo mixture of adducts 110 (R = Ph), in 82% yield (Scheme 3.30). 

It is prepared by treating ethyl cinnamate with peracetic acid [212] or by condensation of benzaldehyde with ethyl chloroacetate (in the above Darzens reaction, R = H). The glycidate is used as a long-lasting fragrance material for creating harmonic, fruity notes in household and fine fragrances. 

Pinacol rearrangement driven by the release of the ring strain of a cyclobutane ring has been employed in an extremely efficient manner to form cyclopentanone derivatives. Experimentally. the Lewis acid mediated aldol condensation of benzaldehyde with l,2-bis(trimethyl-siloxy)cyclobutcne at —78 C gave the pinacol 1 in its silylated form.35,36 Subsequent treatment of this pinacol with trifluoroacetic acid at room temperature afforded 2-phenyl-cyclopentane-l,3-dione (2) in 97% yield.35,36... 

Examples are the formation of diacetone alcohol from acetone [reaction type (A)] catalysed by barium or strontium hydroxide at 20—30°C [368] or by anion exchange resin at 12.5—37.5°C [387], condensation of benzaldehyde with acetophenone [type (C)] catalysed by anion exchangers at 25—-45°C [370] and condensation of furfural with nitromethane [type (D)] over the same type of catalyst [384]. The vapour phase self-condensation of acetaldehyde over sodium carbonate or acetate at 50°C [388], however, was found to be first order with respect to the reactant. 

Condensation of benzaldehyde with 2-amino-3-cyano- or -ethoxycar-bonylpyrazolo [ 1,5-a]pyridines gave the corresponding 2-benzylideno derivatives.66 A benzoylamino compound (265) was converted to the urea derivative 266.232... 

Monocyclic systems of this type are poorly represented in the literature and so far only two routes to 3,4-dihydro-2/f- 1,3-oxazines have been described which may be capable of further development. The first depends upon the interconversion of the tetrahy-dropyrimidine (192) into the oxazine (193) by partial hydrolysis, and the second requires the acid-catalyzed condensation of benzaldehyde with the /3-amino ester (194 Scheme 80) (4SJA1382). 

Pigment Green 4 [61725-50-6] 42000 2 triarylcarbonium chloride (Malachite Green) condensation of benzaldehyde with N,N- dimethylaniline, followed by oxidation and salt formation... 

ZEOLITES AS BASE CATALYSTS. PREPARATION OF CALCIUM ANTAGONISTS INTERMEDIATES BY CONDENSATION OF BENZALDEHYDE WITH ETHYL... 

The condensation of benzaldehyde with ethyl cyanoacetate, ethyl malonate and ethyl acetoacetate were carried out with high rates and selectivity promoted by lithium-, sodium, potassium-, and caesium-exchanged X and Y zeolites and on sodium-Germanium substituted faujasite. 

The results in Table 2 show that the pyridine is less active than any of the X zeolites and Ge faujasite except the lithium form which shows slightly lower activity, whereas all Y zeolites show lower activity than pyridine. Piperidine, however, is more active than any of the zeolite samples studied here. From this comparison, it appears that, most of the basic sites of the zeolites must have pK<10.3. However, the fact that zeolites are also active for catalyzing the condensation of benzaldehyde with ethyl malonate, indicate that these samples have some basic sites with pK< 13.3. On a quantitative bases, and comparing the activity of zeolites for condensation with ethyl cyanoacetate, ethyl acetoacetate and ethyl malonate (Fig. 2), we can conclude that most of the basic sites of the zeolite have pK<9.0 with a sensible amount with 9.0basic strength of different solid base catalysts. 

The formation of naphtho[6c]thiophene-3-ones 106 takes place on acylation of 2-substituted benzo[b]thiophenes 103 with cinnamoyl chloride (78AP710, 78LA627 79LA965). Interestingly, the aromatization of the intermediate 105 occurs with elimination of benzene. Chalcone 104 also may be obtained on acetylation of benzo[fe]thiophene 103, followed by condensation of benzaldehyde with the methyl group of the 3-acetylbenzo[b]thiophene intermediate (79LA965). 

Johnson. N-Bromomethylphthallmide has also been prepared by treatment of H-hydroxymethylphthallmlde with phosphorus tribromide.5 The procedures for the syntheses of the phosphorates 3 and 4 represent modifications of those described by Yamauchi and co-workers.5 Two other routes to 4 have recently been reported by Gross and co-workers.5 Rateliffe and Christensen have also recorded the preparation of diethyl N-benzylideneaminomethylphosphonate (5) by the condensation of benzaldehyde with 4 under virtually identical conditions as detailed herein, but their route to 4 was completely different.6 The submitters have found that the present method for the syntheses of 2-5 gives reproducibly higher yields and is more reliable and convenient than those alternative procedures. 

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