Cascade cyclization of 1,2-diamino-4-phenylimidazole with aromatic aldehydes and cyclohexanediones

The three-component condensation of 1,2-diamino-4-phenylimidazole with aromatic aldehydes and 1,3-cyclohexanediones occurred regioselectively and afforded 3-amino-1-phenyl-10-aryl-7,8-dihydroimidazo[1,5-b] cinnolin-9(5H,6H,10H)-ones.     

Cascade cyclization reactions of 3,4,5-triamino-1,2,4-triazole with aromatic aldehydes and cycloalkanones

A three-component condensation of 3,4,5-triamino-1,2,4-triazole (1) with aromatic aldehydes 2a–f and dimedone (3) or cyclohexanone (8) afforded partially hydrogenated 9-aryl-[1,2,4]triazolo[5,1-b]quinazolin-8-ones. The structure of 2-amino-6,6-dimethyl-3-(4-nitrobenzylidene)amino-9-(4-nitrophenyl)-5,6,7,9-tetrahydro[1,2,4]triazolo[5,1-b]quinazolin-8-one (4e) was confirmed by X-ray diffraction data. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1178–1182, July, 2006.     

Ruthenium (II)-catalyzed synthesis of phthalides via the cascade addition and cyclization of aromatic acids with aldehydes

The ruthenium-catalyzed intermolecular cascade cyclization of aromatic acids with aromatic aldehydes, which involves the direct insertion of C–H bond into a polar C=O bond and the successive intramolecular nucleophilic substitution, was developed for the synthesis of 3-substituted phthalides in good to excellent yields. This one-pot procedure characterizes in a short reaction time, the cheaper Ru(II) as a catalyst, readily available acids and aldehydes as starting materials, and water as the only theoretical by-product.These merits make the protocol an efficient and cost-effective route for the synthesis of 3-substituted phthalides.     

Study of regioselectivity of reactions between 3(5)-aminopyrazoles and 2-acetylcycloalkanones

Regioselectivity was examined of reactions between nine 3(5)-aminopyrazoles and 2-acetylcyclopentanone and 2-acetylcyclohexanone under various conditions. A series of cyclopenta[e]pyrazolo-[1,5-a]pyrimidines was obtained. The highest regioselectivity of the reaction was observed in alcohol at 20°C in the presence of a catalytic quantity of trifl uoroacetic acid. The regiostructure of compounds was established by ¹H and ¹³C NMR spectroscopy.     

Condensation of 5-quinolylamine with aromatic aldehydes and dimedone

Condensation of 5-quinolylamine with dimedone and aldehydes of aromatic and heteroaromatic series afforded 10,10-dimethyl-7-aryl(heteryl)-7,10,11,12-tetrahydro-9H-benzo[b]-1,7-phenanthrolin-8-ones.     

Switchable selectivity in multicomponent heterocyclizations of acetoacetamides, aldehydes, and 3-amino-1,2,4-triazoles/5-aminopyrazoles

Multicomponent heterocyclizations of 3-amino-1,2,4-triazoles/5-aminopyrazoles with acetoacetamides and aromatic aldehydes were studied in detail using conventional thermal heating, ultrasonication, and microwave irradiation. Several different synthetic pathways for these cyclocondensations occurring under either kinetic or thermodynamic control were established depending on the temperature regime and building block selection. The experimental data obtained and the procedures developed allow tuning selectivity of the multicomponent reactions studied.     

Mechanistic studies on the B(C(6)F(5))(3) catalyzed allylstannation of aromatic aldehydes with ortho donor substituents

Mechanistic studies on the B(C(6)F(5))(3) catalyzed allylstannation of isomeric substituted benzaldehydes are reported. Confirming a report by Maruoka et al., good (5:1) to excellent (>20:1) selectivities for ortho over para isomers are observed when 1:1 mixtures (X = OMe, Cl, F, OTBS) are allylstannated with C(3)H(5)SnBu(3) in the presence of B(C(6)F(5))(3) (2.5% per CHO). The best selectivities are observed for the anisaldehydes. Multinuclear NMR studies on solutions of B(C(6)F(5))(3) and C(3)H(5)SnBu(3) (1:1 to 1:5) show that the borane abstracts the allyl group from the organotin reagent, forming an adduct (C(6)F(5))(3)B...CH(2)CHCH(2)SnBu(3), 1, or ion pair [(C(6)F(5))(3)BCH(2)CH=CH(2)](-)[Bu(3)SnCH(2)CHCH(2)SnBu(3)](+), 2, depending on the reagent ratio. These compounds are important in the mechanism of Lewis acid catalyzed 1,3-isomerization of substituted allyl stannanes. When allyltin reagent is added to solutions of B(C(6)F(5))(3) and ortho-anisaldehyde (1:5) at -60 degrees C, conversion to the stannylium ion pair [Bu(3)Sn(ortho-anisaldehyde)(2)](+)[o-ArCH(allyl)OB(C(6)F(5))(3)](-), o,o-4, is observed. The structure of this species was confirmed by (1)H, (11)B, (19)F, and (119)Sn NMR spectroscopy and by forming related ion pairs (o-5 and o,o-5) utilizing the [B(C(6)F(5))(4)](-) counteranion via reaction of [Bu(3)Sn](+)[B(C(6)F(5))(4)](-) with aldehyde. The anion in o,o-4 is formed via direct allylation of the ortho-anisaldehyde/B(C(6)F(5))(3) adduct o-3, while the cation arises upon aldehyde ligation of the resulting tributylstannylium ion. The crystal structure of the related derivative ortho-C(6)H(4)(OMe)CHO x SnMe(3)BF(4), 6, showed that the aldehyde binds the tin nucleus only through the carbonyl oxygen. Similar reactions using para-anisaldehyde show that formation of p,p-4 occurs at a much slower rate, again demonstrating the preference for the ortho substituted substrates. For similar experiments using benzophenone, however, formation of the ion pair [Bu(3)Sn(Ph(2)CO)(2)](+)[(C(3)H(5))B(C(6)F(5))(3)](-), 8, was observed, illustrating the differences subtle changes in substrate can bring. Ion pair 8 is formed via the trapping of 1 by the benzophenone substrate. In the presence of excess aldehyde and allyltin reagent, ion pair o,o-4 catalyzes the allylstannation of aldehyde to give the product stannyl ether. Several lines of experimental evidence suggest this is the true catalyst in the system. The chemoselectivity observed thus does not rely on classical chelation control in any way. Rather, we propose that the ortho donor group stabilizes the developing positive charge at the beta carbon of the allyl group and the tin atom during the allylation event. This stabilization renders the ortho substituted substrates kinetically favored toward allylation irrespective of the Lewis acid employed.     

Tuning of chemo- and regioselectivities in multicomponent condensations of 5-aminopyrazoles, dimedone, and aldehydes

Regio- and chemoselective multicomponent protocols for the synthesis of 1,4,6,7,8,9-hexahydro-1H-pyrazolo[3,4-b]quinolin-5-ones, 5,6,7,9-tetrahydropyrazolo[5,1-b]quinazolin-8-ones, and 5a-hydroxy-4,5,5a,6,7,8-hexahydropyrazolo[4,3-c]quinolizin-9-ones starting from 5-amino-3-phenylpyrazole, cyclic 1,3-dicarbonyl compounds and aromatic aldehydes are described. Whereas the three-component coupling in ethanol under reflux conditions provides mixtures of pyrazoloquinolinones and pyrazoloquinazolinones, the condensation can be successfully tuned toward the formation pyrazoloquinolinones (Hantzsch-type dihydropyridines) by performing the reaction at 150 degrees C in the presence of triethylamine base applying sealed vessel microwave or conventional heating. On the other hand, using sonication at room temperature under neutral conditions favors the formation of the isomeric pyrazoloquinazolinones (Biginelli-type dihydropyrimidines). These products are also obtained when the three-component condensation is executed in the presence of trimethylsilylchloride as reaction mediator at high temperatures. A third reaction pathway leading to pyrazoloquinolizinones in a ring-opening/recyclization sequence can be accessed by switching from triethylamine to a more nucleophilic base such as sodium ethoxide or potassium tert-butoxide. The reaction mechanism and intermediates leading to these three distinct tricyclic condensation products are discussed.     

Three-component condensation of 2-naphthylamine with aromatic aldehydes and 5-(2-furyl)-1,3-cyclohexanedione

Three-component condensation of 5-(2-furyl)-1,3-cyclohexanedione with 2-naphthylamine and aromatic or heteroaromatic aldehydes afforded 12-aryl(hetaryl)-9-(2-furyl)-7,8,9,10,11,12-hexahydrobenzo[a]-acridin-11-ones possessing two asymmetric carbon atoms (C⁹ and C¹²). The products were found to be formed as mixtures of diastereoisomers.     

Electrocatalytic multicomponent cyclization of aromatic aldehydes,malononitrile, and malonates into 3-substituted 2,2-dicyanocyclopropane-1,1-dicarboxylates

Electrolysis of aromatic aldehydes, malononitrile and malonates in methanol in an undivided cell in the presence of double-mediator system NaBr-NaOAc afforded 3-substituted 2,2-dicyanocyclopropane-1,1-dicarboxylates in 40–60% yields.     

无外加催化剂条件下邻取代芳香醛与5, 5-二甲基-1, 3-环己二 酮的反应研究

在DMF溶剂中,不外加催化剂使邻取代芳香醛(1)与5,5-二甲基-1,3-环己二酮(2)发生缩合和加成反应生成3,3,6,6-四甲基-4a-羟基-9-芳基-1,8-二氧代-2,3,4,4a,5,6,7,8,9,9a-十氢化-1H-氧杂蒽(3a-3d)。在同样条件下,邻羟基芳香醛与5,5-二甲基-1,3-环己二酮则发生缩合、加成和脱水反应生成3,3-二甲基-9-(5,5-二甲基-3-羟基-2-环己烯-1-酮-2-基)-1-氧代-2,3,4,9-四氢化-1-氧杂蒽(4a-4b)。用单晶X-射线分析法确定了产物3a和4a的晶体结构。     

Thermal cyclization of α -nit ros o-β-naphthol,o-nitronaphthols,and o-nitrophenols with aromatic aldehydes

The possibility of obtaining 2-aryl-substituted benzoxazoles and naphthoxazoles by heating o-nitrophenols, o-nitronaphthols, and -mtroso--naphthol with aromatic aldehydes in highboiling solvents with simultaneous removal of the water formed by distillation is demonstrated.Communication VI of the series Structure and Properties of Nitroso Compounds. See [1] for communication V.The preparation of XVI was carried out in mesitylene, while the other compounds were prepared in tetralin (10–20 ml of solvent per 0.03 mole of the hydroxy compound). In the preparation of III, VIII, XIII, and XVI-XVIII, 3 moles of aldehyde were introduced into the reaction per mole of hydroxy compound, while 5 moles of the aldehyde per mole of hydroxy compound were used in the remaining cases. Compounds XVI-XVIII were obtained from -nitroso--naphthol, XXI-XXIIwere obtained from -nitro--naphthol, and XIX-XX were obtained from -nitro--naphthol.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 10–11, January, 1972.     

Condensation of quinolin-5-amine with aromatic aldehydes and cyclohexane-1,3-dione

7-Aryl(hetaryl, cyclohexenyl)-7,10,11,12-tetrahydrobenzo[b][1,7]phenanthrolin-8(9H)-ones were synthesized by three-component condensation of aromatic and heteroaromatic aldehydes and cyclohex-3-ene-1-carbaldehyde with quinolin-5-amine and cyclohexane-1,3-diones.     

SmI2-induced cyclization of (E)- and (Z)-β-alkoxyvinyl sulfones with aldehydes

SmI₂-induced reaction of (E)- and (Z)-β-alkoxyvinyl sulfones onto an aldehyde function afforded 2,6-syn-2,3-trans- and 2,6-syn-2,3-cis-tetrahydropyran-3-ols, respectively, via stereoselective cyclization. This reaction was applied to the synthesis of 2-methyl-tetrahydropyran, corresponding to the N-ring of gymnocin-A, and 2-exo-methylene-tetrahydropyran, a key intermediate for convergent synthesis of polycyclic ethers based on the Suzuki–Miyaura reaction.     

The reactions of 5-aryl-2,3-dimethylisoxazolium salts with aromatic aldehydes

The reactions of the 3-methyl group in 5-aryl-2,3-dimethylisoxazolium tetrafluoroborates with aromatic aldehydes, in the presence of piperidine were studied. Isoxazolium salt reactivity is independent of the phenyl group substituent at C-5 on the isoxazolium salt ring. However, it does depend on the aldehyde structure.     

Features of switchable multicomponent heterocyclizations of salicylic aldehydes and 5-aminopyrazoles with pyruvic acids and antimicrobial activity of the reaction products

Three-component reactions of 5-aminopyrazoles and salicylic aldehydes with pyruvic acids were studied. The method of tuning of the selectivity of the heterocyclizations allowing to change its direction by variation of the reaction parameters was worked out. The treatment involving pyruvic acid can be selectively directed to the formation to either 3-aryl-10,11-dihydro-4,10-methano-pyrazolo[4,3-c][1,5]benzoxazocine-4-carboxylic acids or 3,6-diarylpyrazolo[3,4-b]pyridine-4-carboxylic acids, while the reaction involving arylpyruvic acid leads only to 7-hydroxy-2,5,6-triaryl-4,5,6,7-tetrahydro-pyrazolo[1,5-a]pyrimidine-7-carboxylic acids. Antimicrobial activity of the compounds obtained was also studied: Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus) were found sensitive to the substances tested, however, only in the highest concentration.     

Condensation of 2,4(3H,5H)-furandione with heteroaromatic aldehydes

2,4(3H,5H)-Furaridione, 1 , condenses with heteroaromatic aldehydes in the presence of concentrated hydrochloric acid to yield 3-(heteroarylmethylene)-2,4(3H,5H)-furandiones, 4 . The condensation of 1 with acid sensitive aldehydes, including 2-furanacroleine and N-methylpyrrole-2-carboxaldehyde proceeded well with 1 as the sole proton source. The E/Z ratio of type 4 compounds was determined by ¹H-nmr spectroscopy.     

Bisindoles. 15. Acidic condensation of bis(2-ethoxycarbonyl-5-indolyl) oxide and bis(2-ethoxycarbonyl-5-indolyl)methane with aromatic aldehydes

The acidic condensation of bis (2-ethoxycarbonyl-5-indolyl) oxide and bis(2-ethoxycarbonyl-5-indolyl)methane with aromatic aldehydes was studied. Bis(3-chloro) compounds with labile chlorine atoms, by nucleophilic substitution of which the corresponding dimethylamino, hydroxy, methoxy, acetoxy, cyano, and mercapto derivatives were obtained, were isolated.See [1] for communication 14.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 365–368, March, 1983.     

Cyclocondensation reactions of 5-aminopyrazoles, pyruvic acids and aldehydes. Multicomponent approaches to pyrazolopyridines and related products

The reactions of 3-substituted 5-aminopyrazoles with arylidenepyruvic acids and their synthetic precursors, pyruvic acid and aromatic aldehydes, were studied. Several different reaction pathways for these cyclocondensation reactions were established depending on the reaction conditions and building block selection. The formation of pyrazolo[3,4-b]pyridine-6-carboxylic acids as major products and related compounds was discussed from the mechanistic point of view.