Reaction cyclo-condensation

The original compound, maleimide (2,5-dioxo-A -pyrroline), is synthesized by the cyclo-condensation of ammonia and maleic acid. Similarly, primary amine is added to maleic anhydride, followed by cyclocondensation, to form N-substituted maleimide (Fig. 2). This reaction is applied to the preparation of bis-maleimides (BMl) [1]. At first, BMI was used as a crosslinking agent for natural rubber (NR). An o-dichlorobenzene solution of NR was crosslinked by BMI at I08-150°C in the presence of peroxides. The radicals generated from peroxides react with the double bonds of both BMI and NR [ 1 ]. 

The synthesis of pyrido[2,3-d]pyrimidin-7(8H)-ones has also been achieved by a microwave-assisted MCR [87-89] that is based on the Victory reaction of 6-oxotetrahydropyridine-3-carbonitrile 57, obtained by reaction of an Q ,/3-unsaturated ester 56 and malonitrile 47 (Z = CN). The one-pot cyclo condensation of 56, amidines 58 and methylene active nitriles 47, either malonitrile or ethyl cyanoacetate, at 100 °C for benzamidine or 140 °C for reactions with guanidine, in methanol in the presence of a catalytic amount of sodium methoxide gave 4-oxo-60 or 4-aminopyridopyrimidines 59, respectively, in only 10 min in a single-mode microwave reactor [87,88]... 

Feist-Benary cyclo-condensation of (2,4-dioxobutylidene)-phosphoranes with a-chloroacetone gave rise to substituted furfuryl phosphonium salts, which underwent subsequent Wittig reactions to afford alkenylfurans in good yields as can be seen below <06JOC8045>. 

Only non-enolizable eneones give satisfactory yields of hydrodiroer on reduction in aptotic solvents [83]. A suitable aqueous buffer is needed with enolizable eneones to control base catalysed side reactions of condensation and oligomerisation. The polarographic behaviour of eneones in buffers is illustrated using cyclo-... 

Akhrem et al. cyclo-condensed 3-acetyltetramic acid (39) with isoquinoline 53 to compounds (55) showing an azasteroid structure (78DOK595 90ZOR2382). Obviously, referring to (39), an aldol-like reaction, analogous to (39) - (42), involving position 1 of the isoquinoline, occurred to give (54). 

Reaction XLVII. Condensation of an Ester with itself by the action of Iodine on its Sodio-derivative. (B., 23, R., 141 A., 201, 144 266, 88.) When iodine, usually in ethereal solution, acts on the sodio-derivatives of esters, such as malonic or acetoacetic esters, the metal is eliminated, and higher dibasic esters are obtained. As will be seen, the reaction is especially useful for preparing cyclo-paraffins by acting with iodine (or bromine) upon disodio-methylene- and disodio-ethylene-, etc., di-malonic esters. 

Kempter and co-workers prepared benzodiazocines 134 (R = R1 = H R2 = H, Me) from 135 (R = H, Me) by reduction and subsequent cyclo-condensation with the appropriate carbonyl compound (75MI7 87ZC36). For example, these workers condensed 3-(o-aminophenyl)propylamine with either phosgene or alkyl chloroformate to obtain 134 (R = R1 = R2 = H, X = O). Reaction of the same diamine (77MI5 87ZC36) and substituted derivatives (77MI5) with carbon disulfide afforded thio-... 

The use of 2,6-diaminopyrimidin-4-one 52 in a related solution phase cyclo condensation reaction with various aldehydes and 1,3-dicarbonyl compounds furnished a number of pyrido[2,3-d]pyrimidines 53 [102], The ZnBr2-catalyzed reactions proceeded much faster under microwave heating conditions than in an oil-bath, requiring only 20 min dielectric heating at 160 °C (vs. 3 days at 110 °C with oil-bath heating) to go to comple-... 

Compounds bearing the 1,4-benzodiazepine moiety have potential use as anxiolytic agents. One of the methods for the synthesis of this heterocyclic system involves the reaction of 1-a-chloroacetylisatin with hexamethylenetetramine in methanol, thus yielding the 1,4-benzodiazepine-5-carboxylic ester via solvolysis of the TV-acylisatin and the in-situ nucleophilic substitution of chloride, generating the glycine amide that subsequently undergoes cyclo-condensation (Scheme 53). 

A novel cyclo-condensation was reported between l,l-bis(trimethylsilyloxy)ketene acetals 164 and isoquinolinium salts 165 <05TL8997>. This reaction resulted in the carboxylic acid 166 in moderate to good yields. Ultimately, this isoquinoline derivative 166 was used to make a series of 7,8-benzo-9-aza-4-oxabicyclo[3.3.1]nonan-3-ones 167 shown in Scheme 47. 

Bixchler Napiralski, Dieckmann cyclization [15], Suzuki reaction [48], Wittig reaction, ozonolysis, condensation, esterification, nucleophilic substitution [49], Henry reaction, 1.3-dipolar cyclo-addition, electrophilic addition [50], oxidation chloride -> aldehyde [50], sulfide —> sulfone [51], alcohol —> ketone, Arbuzov reaction (phosphine-phosphorox-ide) [52], reduction hydration [45], ester -> alcohol [49, 53]... 

Combination of a cyclo-condensation reaction, multicomponent diversification and multidirectional cleavage from the resin using a novel combined "safety-catch"- and traceless linker yielding highly diverse pyrimidines by D. Obrecht et al. (Chimia 1996, 11, 530 Helv. Chim. Acta 1997, 80, 65) and L. M. Gayo et al. (Tetrahedron Lett. 1997, iS, 211). 

Reaction of thiazolic 387 and thiazinic 388 diazadienes with a wide variety of ketenes resulted in a [4 4- 2] cyclo-condensation which provided 5H-thiazolo[3,2-(j]pyrimidin-5-ones 389 and 2H,6H-pyrimido[2,l-l)][l,3] thiazin-6-ones 390, respectively, via elimination of dimethylamine (Scheme 119) (2003JOC4912, 1999JCR(S)36). 

A similar cyclo-condensation reaction as between glycoluril and formaldehyde that gives rise to the cucurbiturils is the basis of a third class of basket-Uke molecules. In 1872 Baeyer reported the formation of resinous material from the reaction of formaldehyde and phenol which was the basis for the work of Baekeland s discovery of the first synthetic plastic that had practical application, Bakelite [8]. 

The case of nitrobenzene anchored to H-terminated (100) Si surfaces through cyclo-condensation reaction of nitrobenzene at 473 K (-200 °C) was studied by Perrine et al. [215]. The cyclocondensation reaction results in the presence of three surface species, which are the nitrosoadduct [N(Si)0(Si)] as the main component, followed by the phenylnitrene adduct (ONSi ) and a stable intermediate as the minor species. After an annealing treatment to 823 K (-550 °C) for 30 s, the concentration of phenylnitrene substantially increases, whereas the other two species decrease slightly, but the nitrosoadduct remains the major product. This observation suggests that those species undergo a conversion into phenylnitrene adducts. The fact that all the three components are still present upon this annealing treatment indicates that they are thermally stable at this temperature. 

The major forms of iso thiocyanates present in urine are N-acetyl-cysteine conjugates (mercapturic acids) and these have been measured using HPLC with MS detection (Chung et al 1992 Conaway et al 2000 Fowke et al 2003 Petri et al 2003 Rouzaud et al 2004). Appropriate standards can be readily synthesized. Figure 8.9 shows the reaction of an isothiocyanate with 1,2-benzenedithiol which gives rise to a cyclo-condensation product (l,3-benzodithiole-2-thione) and an amine (R-NH2). 

Tropolone has been made from 1,2-cycloheptanedione by bromination and reduction, and by reaction with A -bromosuccinimide from cyolo-heptanone by bromination, hydrolysis, and reduction from diethyl pimelate by acyloin condensation and bromination from cyclo-heptatriene by permanganate oxidation from 3,5-dihydroxybenzoic acid by a multistep synthesis from 2,3-dimethoxybenzoic acid by a multistep synthesis from tropone by chlorination and hydrolysis, by amination with hydrazine and hydrolysis, or by photooxidation followed by reduction with thiourea from cyclopentadiene and tetra-fluoroethylene and from cyclopentadiene and dichloroketene. - ... 

Frensch and Vdgtle have recently appended three crown ether units to the cyclo-triveratrylene unit . Note that Hyatt had previously prepared the open-chained relatives of this structure (see Sect. 7.3 and Eq. 7.6). Whereas Hyatt prepared the cyclo-triveratrylene skeleton and then appended polyethyleneoxy arms to it, Frensch and Vogtle conducted the condensation reaction (formaldehyde/HCl) on the preformed benzocrown. Thus benzo-15-crown-5 was converted into the corresponding tris-crown (IS) (mp 203.5—205.5°) in 4% yield. The yield was somewhat higher for the condensation of benzo-18-crown-6, but in both cases, yield ranges were observed. These species formed 1 3 (ligand/salt) complexes with sodium and potassium ions. 

---