One-pot condensation

Compound 7-ethyl-7-methyl-3-phenyl-2,3,4,9-tetrahydropyrimido[l,2-tf][l,3,5]triazine-6,8-dione 71 <2002JHC663> was prepared by the one-pot condensation reaction of 6-amino-3-cthyl-3-mcthyl-5//-pyndinc-2,4-dionc 70 with aromatic amines and formaldehyde (Equation 3). 

Amino-4//- 1,3-thiazines have been obtained from a three-component one-pot condensation using alkynes, thiourea and aryl aldehydes (Scheme 67).156... 

A majority of the hyperbranched polymers reported in the literature are synthesized via the one-pot condensation reactions of A B monomers. Such one-step polycondensations result in highly branched polymers even though they are not as idealized as the generation-wise constructed dendrimers. The often very tedious synthetic procedures for dendrimers not only result in expensive polymers but also limit their availability. Hyperbranched polymers, on the other hand, are often easy to synthesize on a large scale and often at a reasonable cost, which makes them very interesting for large-scale industrial applications. 

One-pot condensation of an aromatic aldehyde, urea, and ethyl acetoacetate in the acidic ethanolic solution and expansion of such a condensation thereof. It belongs to a class of transformations called multicomponent reactions (MCRs). 

Novel 3-aryl-2-imino-4-methyl-2,5-dihydrofurans have also been efficiently synthesised using focused microwave heating by a one-pot condensation from a-ketols and substituted phenylacetonitrile in the presence of sodium ethoxide in ethanol (Scheme 3.2)4. 

Oxadiazoles have often attracted the attention of medicinal chemists as stable bioiso-steres of metabolically labile esters. 1,3,4-Oxadiazoles are generally prepared by cyclodehydration of 1,2-diacylhydrazines or their equivalents. Symmetrical 2,5-disubstituted examples were able to be rapidly prepared in a one-pot condensation-cyclodehydration of benzoic acids (2 equiv) with hydrazine dihydrochloride, in the presence of... 

The famous Ugi reaction, the one-pot condensation of a carboxylic acid, an amine, an aldehyde or ketone and an isocyanide to yield an a-acylaminoamide, have recently been used as an efficient method for the synthesis of diverse libraries of small organic molecules such as benzodiazepines, pyrroles, lactams and diketopiperazines2. Even though some solution-phase Ugi reactions proceed rapidly, such reactions on solid phase have been found to take between one and several days. In 1999, Hoel and Nielsen17 performed the first microwave assisted, solid phase Ugi four-component condensation (see Scheme 5.5). 

These in situ oxidations, followed by condensation with a phosphorous reagent, are normally not possible on ketones, because of their lack of reactivity with stabilized phosphoranes and phosphonate anions. Nevertheless, one-pot condensation with ketones can occur in very favourable... 

A three-component one-pot condensation of 2-aminomethylpyridines 446, aldehydes, and isocyanides afforded 3-substituted 4-aminopyrido[l,2-fl] pyrazinium salts 447 (05OL2517) and not 4-(2-pyridyl)imidazols 448, as was stated earlier (05OL39). 

A few years previously, the same research group reported a one-pot condensation of three components (methylphenylglyoxylate (MPG), aniline, and aromatic aldehyde), promoted by a TiCl3/pyridine system under anhydrous conditions, for the diasteroselective synthesis of P-amino-a-hydroxyesters (Equation 14.24) [32]. 

The one-pot condensation of an ester enolate with an imine is a very powerful synthetic procedure toward azetidin-2-ones (Equation 183). Various types of esters and imines can be utilized. Although in the vast majority the reactions have been mediated by lithium, various other metals mediate the reaction as well. Some examples include zinc, aluminium, tin, boron, indium, and titanium <1996MI119>. Theoretical studies on these reactions have been reviewed <1998JCC1826>. 

Dihydrothieno[3,4-d]pyrimidin-3(l//)-ones 337 were synthesized by a four-step reaction sequence starting from carbamates 310. The latter were selectively reduced with lithium aluminum hydride and then oxidized with activated manganese(IV) oxide to give aldehydes 334 in one-pot. Condensation of compounds 334 with ethanolamine in refluxing ethanol afforded the Schiff bases 335, which were reduced with sodium borohydride to... 

A new method for the ortho hydroxylation of aromatic aldehydes via orrho-lithiated arcnnatic aminoal-koxides has recently been reported by Einhom et al Fonnation of the aminoalkoxide serves two purposes. Firstly, the aldehyde group is protected and, secondly, the aminoalkoxide directs lithiation to the ortho position. Oxidation of the lithio species was effected by either MoOPH or molecular oxygen, albeit in poor yield. Alternatively, a two-step, one-pot condensation of the lithio intermediate with tributyl borate followed by oxidation with hydrogen peroxide gave the ortho-hydroxy aldehydes (24) in slightly better yields (Scheme 9). 

The synthesis of siloxane-polyimide elastoplastics requires an approach slightly different from that used in preparing the thermoplastic materials because of differences in reactivity between the aliphatic-anhydride-terminated siloxane oligomers and the aromatic dianhydrides. A one-pot condensation of the anhydride-terminated siloxane oligomers, BPADA, and the diamine in o-dichlorobenzene solution in the presence of 2-hydroxypyridine as catalyst leads to a siloxane-deficient polyimide. To circumvent this deficiency, a two-step synthetic scheme was used in which the anhydride-terminated siloxane oligomers were first capped with an excess of the diamine. The aromatic dianhydride was then added to the resulting amic acid oligomeric mixture and warmed to complete imidization (Scheme IV). 

Arylquinoxalines 28 are obtained in a one-pot condensation reaction of 3-arylisoxazol-5(4f/)-ones and benzene-1,2-diamines in good yields. 2-Arylbenzimidazoles are formed as minor products. ... 

A potentially practical synthesis of weTO-diarylsapphyrins has recently been introduced by Sessler and Kodadek. It involves the one-pot condensation reaction between diformyl bipyrrole 5.10, pyrrole 5.29, and benzaldehyde 5.30 using BF3 MeOH as the Lewis acid catalyst. In this 2 -I- 1 + I + 1 approach, careful control of the ratio of starting materials is required. When run properly, however, this one-step procedure allows for the preparation of 10,15-diphenylsapphyrin 5.33 in ca. 10% yield (Scheme 5.2.1). In a similar fashion, the P-CH3- and p-CN-deriva-tives 5.34 and 5.35 were prepared using the appropriately substituted benzaldehyde... 

Oxazolidinediones have been prepared by one-pot condensation of benzyl cyanides, isocyanates, and 2-chloro-2-oxoacetate as shown in Scheme 85. The anion derived from BuLi deprotonation of benzyl cyanide attacks the isocyanate to give intermediates 306, which can undergo condensation and cyclization with ethyl oxalyl chloride to give the 4,5-oxazolidinedione products <2004SL1963>. 

In our laboratories, the reaction of phosgene with methyl N-methyl carbamate by an improvement of the procedure described in the literature (Ref. 208] afforded methyl N-chlorocarbonyl-N-methyl carbamate (I) in high yield. The one-pot condensation of the intermediate (1) led to Methazole in excellent yield as depicted in scheme 151. 

Bose, D. S., Fatima, L., Mereyala, H. B. Green Chemistry Approaches to the Synthesis of 5-Alkoxycarbonyl-4-aryl-3,4- dihydropyrimidin-2(1 H)-ones by a Three-Component Coupling of One-Pot Condensation Reaction Comparison of Ethanol, Water, and Solvent-free Conditions. J. Org. Chem. 2003, 68, 587-590. 

SCHEME 1. One-pot condensation of t-butylphenol 1 to form calix[ ]arenes 2. The p-unsubstituted calixarenes (see Section V.A.) wiU be characterized by 2h... 

Calixquinones can be easily reduced to the corresponding calixhydroquinones (Zn/HCl or Na2S204) . The calix[8]hydroquinone 57b, however, was prepared from the octabenzyl ether 57a obtained by one-pot condensation in a mixture with the analogous calix[6]- and -[7]arene. Oxidation of 57b to the respective octaquinone was not reported, but the ewrfo-ether 57c was obtained by exhaustive 0-propylation prior to the cleavage of the benzyl ether groups . Inherently chiral derivatives of a calix[4]arene monoquinone have been obtained by 1,4-addition of various nucleophiles to the quinoid system. 

In 2008, Rostamizadeh and his coworkers reported that one-pot condensation of hydrazine hydrate with phenylisothiocyanate and benzaldehydes in the presence of [bmim][BF ] led to the formation of 1,3,4-thiadiazoles in excellent yields during relatively short reaction times (Fig. 12.3) [3]. A mechanism was proposed for these reactions (Fig. 12.4). From where it can be observed that after from formation of... 

The classical Biginelli synthesis is a one-pot condensation using P-dicarbonyl compounds with aldehydes (aromatic and aliphatic ones) and urea or thiourea in ethanol solution containing catalytic amounts of acid. Peng et al. for the first time reported a novel method for the synthesis of dihydropyrimidinones by three-component Biginelli condensations of aldehydes with 1,3-dicarbonyl compounds and urea using room temperature ionic liquids based on [bmim][BF ] or [bmim][PFJ as catalyst under solvent-free and neutral conditions (Fig. 12.15) [11]. 

A three-component, one-pot condensation reaction was described by Yavari and Kowsari [56] by using the [bmim]0H-H20 system to give the functionalized pyrroles in excellent yields. When the benzoyl chlorides, i -phenylalanine, and acety-lenedicarboxylates were allowed to react under an organic alkah catalyst, [bmim] OH-H O provided highly functionalized pyrroles (96% yield) within 15 min (Scheme 17.10). 

Scheme 17.10 A one-pot condensation using the [bmimJOH-H O system to synthesize the functionahzed pyrroles...

Various chiral and achiral derivatives of the fra 5-acetonitrile bis(iminophosphine) [6.5.6]-P-N-N-P iron complexes can be synthesized by a one-pot condensation/ template reaction involving [FeCH OlglfBF ], 3 (2 equiv.), and a diamine (26-28) to yield complexes (29-31) (Scheme 9). These new compounds were tested for catalytic activity in the DH of acetophenone to 1-phenylethanol. Low to moderate conversions were observed in most cases at room temperature and 25 atm H pressure, with precatalyst 29 being able to achieve up to 95% conversion at 50 °C in 18 h. Only complex (R,R)-31 was enantioselective [ee of 61% (5)], but with poor conversion (4%) at elevated temperatures. 

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