Cyclocondensation reaction of heterocyclic carbonyl compounds . The direction of competitive cyclocondensation between carbonyl groups of 6‐azauracile and 1,2‐dihydro‐quinoxalin‐2‐one cycles

In the article the study of cyclocondensation of 3‐[2‐amino‐3‐(3,5‐dioxo‐2,3,4,5‐tetrahydro[1,2,4]‐triazme‐6‐yl)phenyl]‐2,3‐dihydro‐quinoxalin‐2‐one 5 is described and it was found, that the reaction does not proceed by both possible directions, but only cyclization with the carbonyl group of 6‐azauracile cycle proceeds. The 6‐(3‐oxo‐3,4‐dihydro‐quinoxaline‐2‐yl)‐4H‐2,3‐dihydro[1,2,4]triazino[5,6‐b]indol‐3‐one 6 was formed in this way. This course of cyclocondensation was confirmed by the fact, that the product 6 , mentioned above, is quite different from isomeric compound 7 , prepared unambiguously by condensation of 7‐(6‐azauracile‐5‐yl)isatine 8 with o‐phenylenediamine.     

Cyclocondensation reactions of heterocyclic carbonyl compounds XI . Synthesis and study of cyclocondensation reactions of some 3‐substituted‐5‐(2‐aminobenzyl)‐1H‐[1,2,4]triazine‐6‐ones

A series of 2‐substituted‐4‐(2‐nitrobenzylidene)‐4,5‐dihydrooxazol‐5‐ones ( 2a‐2i ) was prepared by the Erlenmeyer's synthesis of 2‐nitrobenzaldehyde with acylglycines ( 1a‐1i ) and the series of corresponding aminoderivatives ( 3b‐3d and 3g‐3i ) was synthetised by catalytic hydrogenation of ( 2b‐2d and 3g‐3i ). Hydrazinolysis of azlactones ( 2 ) and ( 3 ) gave hydrazides ( 4 ) and ( 5 ). The hydrazides ( 5 ) were also obtained by catalytic hydrogenation of corresponding nitroderivatives ( 4 ). The cyclization reaction of hydrazides ( 4 ) or ( 5 ) proceeded to 3,5‐disubstituted‐1,6‐dihydro‐[1,2,4]triazine‐6‐ones ( 6 ) or ( 7 ). Aminoderivatives ( 7 ) were also obtained by reduction of nitro group of compounds ( 6 ). The aminoderivatives ( 7 ) were then cyclized to 3‐substituted‐1,5‐dihydro‐[1,2,4]triazino[6,5‐b]quinolines ( 9 ), resp. its tautomers ( 10 ).     

NMR studies on 1,2‐dihydro‐2‐(4‐aminophenyl)‐4‐[4‐(4‐aminophenoxy)‐4‐phenyl]‐(2H)phthalazin‐1‐one

An unsymmetrical heterocyclic diamine, 1,2‐dihydro‐2‐(4‐aminophenyl)‐4‐[4‐(4‐aminophenoxy)‐4‐phenyl]‐(2H)phthalazin‐1‐one, was synthesized. Its ¹H and ¹³C NMR spectra were completely assigned by utilizing the two‐dimensional heteronuclear ¹³C–¹H multiple‐bond coherence (HMBC) spectroscopy, and heteronuclear ¹³C–¹H one‐bond correlation spectroscopy, homonuclear shift correlation spectroscopy (H,H‐COSY) and rotating frame Overhauser enhancement spectroscopy (ROESY). The structure of the compound was shown to be the phthalazinone rather than the phthalazine ether from cross peaks and chemical shifts of the protons. Copyright © 2002 John Wiley & Sons, Ltd.     

Full Characterization and some reactions of 1‐(2‐adamantyl)‐3‐(1‐adamantyl)aziridin‐2‐one

We found that 1‐(2‐adamantyl)‐3‐tert‐butylaziridin‐2‐one ( 5a ) is unstable. It slowly decomposes at room temperature, although detectable by IR spectroscopy (1840 cm^?1 band in CCl₄). On the other hand, a closely related analogue, 1‐(2‐adamantyl)‐3‐(1‐adamantyl)aziridin‐2‐one ( 5b ), is very stable, in concurrence with an earlier report [1]. We fully characterized aziridinone 5b , identified its thermal decomposition products ( 7 and 8 ) and reacted it with two aprotic ionic (tBuO^? and HO^?) and one protic non‐ionic nucleophile (benzylamine). All three products ( 9b , 10 , and 11 ) result from exclusive cleavage of the lactam (1‐2) bond.     

Synthesis of 5‐(Arylselanyl)‐2‐(arylsulfanyl)benzoates by [3+3] Cyclocondensation of 3‐(Arylsulfanyl)‐1‐(silyloxy)buta‐1,3‐dienes with 2‐(Arylselanyl)‐3‐(silyloxy)alk‐2‐en‐1‐ones

Functionalized 5‐(arylselanyl)‐2‐(arylsulfanyl)benzoates were prepared by [3+3] cyclocondensation of 3‐(arylsulfanyl)‐1‐(silyloxy)buta‐1,3‐dienes with 2‐(arylselanyl)‐3‐(silyloxy)‐alk‐2‐en‐1‐ones.     

Ethyl (E)‐3‐(2‐hydroxy­phenyl)‐2‐(morpholino­carbonyl)­propenoate

The title compound, C₁₆H₁₉NO₅, crystallizes as a centrosymmetric dimer through strong O—H⋯O hydrogen‐bonding interactions between the hydroxy­phenyl and morpholino­carbonyl groups. The morpholino­carbonyl group is almost perpendicular to the propenoate moiety. Electron delocalization in the N—C(=O) fragment leads to the formation of hydrogen‐bonded S(5) ring motifs through C—H⋯O interactions.     

3‐(phenylhydrazono)‐indan‐1‐one and 2‐dimethylaminomethylene‐3‐(phenylhydrazono)‐indan‐1‐one as useful synthons for the construction of new heterocyclic systems

The hydrazone 1 reacts with DMFDMA to give 2‐dimethylaminomethylene‐3‐(phenylhydrazono)‐indan‐1‐one (2) which reacts with hydrazine hydrate and the pyrazole derivative 4 to afford the indenopyrazole derivatives 3 and the indenofluorene 5 respectively. The reaction of 2 with the active methylene compounds, mainly malononitrile, cyanoacetamide and malononitrile dimer was investigated and found to proceed successfully to yield the indenopyran 7 , indenpyridine 8b and trinitrile 9 respectively. Compound 2 reacted with lH‐benzimidazole‐2‐acetonitrile 10 to give to the diazaindenofluorene derivative 11 . Also, 2 reacted with ω‐cyano compounds 12a,b to afford the indenopyran 14 . On the other hand the hydrazone 1 was allowed to react with the enaminones 15, 18 and 21 affording the diazabenzoazulene derivatives 17, 20 and the indeno[1,2‐b]pyridin 23 , respectively.     

Synthesis of multi‐functionalized quinolines and 1,2‐dihydroquinolines through FeCl3‐mediated reactions of carbonyl compounds with 2‐vinylanilines

A facile and efficient approach toward the synthesis of functionalized quinolines and 1,2‐dihydroquinolines from carbonyl compounds and 2‐vinylanilines is described. The protocol utilizes the nonhazardous and less expensive FeCl₃ as catalyst with wide functional group tolerance and avoiding heavy metal impurities in the products.     

[1,1,2,2‐(CO)4‐1,2‐μ‐(CO)‐4,11‐(SMe2)2‐closo‐1,2‐Co2B10H8]

The title compound, 1,1,2,2‐tetra­carbonyl‐1,2‐μ‐carbonyl‐4,11‐di­methyl­sulfido‐closo‐1,2‐dicobaltadodecaborane, [Co₂(C₄H₂₀B₁₀S₂)(CO)₅], has a closo 12‐vertex {1,2‐Co₂B₁₀H₈} structure with SMe₂ ligands at the exo‐4‐ and 11‐positions. The cluster displays close structural similarities to the SEt₂ analogue.     

Reactivity studies of ethyl(Z)‐N‐(2‐amino‐1,2‐dicyanovinyl) formimidate with carbonyl compounds in the presence of base

The reaction of ethyl(Z)‐N‐(2‐amino‐1,2‐dicyanovinyl)formimidate 6 with carbonyl compounds in the presence of triethyl amine occurs with formation of the Schiff s base and intramolecular hydrolysis of the adjacent cyano group to give the alkylideneamino derivatives 8a‐f . When the α‐carbon of the ketone has at least one proton, the prolonged contact of 8a‐f with triethylamine causes intramolecular cyclization between this carbon and the imidate carbon atom to form a seven membered ring. This is followed by cyclization of the cyano and amido groups, leading to the pyrrolo[4,3‐b][1,4]diazepines 9 . If a strong base is used the first ring to be formed is the pyrrole ring as evidenced in the reaction of 8a with 1,8‐diazabicyclo[5.4.0]undec‐7‐ene leading to 14 . The subsequent addition of methyl amine to the reaction mixture, caused cleavage of the alkylideneamino unit and formation of the amidine function from the imi date ( 15 ). The addition of acid to the imidates 8a and 8f led to the diazepine compounds 10a and 10f respectively. A suspension of compound 8e in ethanol and triethylamine evolved to a pyrazinone structure 12 under kinetic conditions (4 hours, room temperature) and to the pyrrolo[4,3‐b][1,4]diazepine 9e under thermodynamic conditions (48 hours, room temperature).     

FeCI3‐promoted [3+3] cycloaddition: Efficient preparation of 1,2‐dihydro‐2‐oxo‐3‐pyridinecarboxylate and 1,2‐dihydro‐2‐oxo‐3‐pyridinecarboxamide derivatives

A facile approach was developed on assembly of the 2‐pyridone nucleus by ferric chloride promoted [3+3] cycloaddition in propionic acid. The tandem process involves cyclization of Michael adduct followed by aromatization. Thus, different substituted 1,2‐dihydro‐2‐oxo‐3‐pyridinecarboxylate and 1,2‐dihydro‐2‐oxo‐3‐pyridinecarboxamide derivatives were prepared in good yields from various enones with malonamic ester and malonamide, respectively     

An Efficient Synthesis of 3‐(3‐benzyl‐2‐(phenylimino)‐2,3‐dihydrothiazol‐4‐yl)‐6‐methyl‐4‐(2‐oxo‐2‐phenylethoxy)‐3,4‐dihydro‐2H‐pyran‐2‐one Derivatives via Multi‐Component Approach

An easy, highly efficient and a new convenient one‐pot, two‐step approach to the synthesis of 3‐(3‐benzyl‐2‐(phenylimino)‐2,3‐dihydrothiazol‐4‐yl)‐6‐methyl‐4‐(2‐oxo‐2‐phenylethoxy)‐3,4‐dihydro‐2H‐pyran‐2‐one is described. These compounds were synthesized from 3‐(3‐benzyl‐2‐(phenylimino)‐2,3‐dihydrothiazol‐4‐yl)‐4‐hydroxy‐6‐methyl‐3,4‐dihydro‐2H‐pyran‐2‐one and α‐bromoketones in good yields. The compounds 4 were synthesized by a multi‐component reaction between 1 , 2 , and 3 and the prominent features of this protocol are mild reaction conditions, operation simplicity, and good to high yields of products.     

The preparation of 3‐substituted 1,2‐benzisothiazole‐1,1‐dioxides from the condensation‐cyclization of dilithiated β‐ketoesters with methyl 2‐(aminosulfonyl)benzoate or 1,2‐benzisothiazol‐3(2H)‐one‐1,1‐dioxide

Several β‐ketoesters were dilithiated with an excess of lithium diisopropylamide, followed by condensation with methyl 2‐(aminosulfonyl)benzoate to give intermediates that were not isolated but cyclized to 3‐substituted 1,2‐benzisothiazole‐1,1‐dioxides. In most instances involving the ester‐sulfonamide, a single β‐ketoester tautomer is usually formed after recrystallization from ethanol. The same dilithiated β‐ketoesters generally condense less well with 1,2‐benzisothiazol‐3(2H)‐one‐1,1‐dioxide (saccharin) under the same conditions to afford the same products usually in the same or lower yields. The use of N,N,N',N'‐tetramethylethylenediamine during these syntheses has sometimes resulted in improved yields of products.     

2‐(Methoxy­carbonyl)phenyl­boronic acid

The structure of the title compound, 2(CH₃OCO)C₆H₄B(OH)₂ or C₈H₉BO₄, involves two crystallographically independent conformers, A and B, in a 1:2 ratio; mol­ecules of conformer A are located on a crystallographic mirror plane. The most striking difference between the two independent mol­ecules is the opposite orientation of the methoxy­carbonyl groups, while the conformations of the boronic acid groups vary more subtly. Mol­ecules of both types are ordered to produce a specific hydrogen‐bonding network that can be inter­preted in terms of a layer lying parallel to (100). Within the layer, B mol­ecules are linked with each other by two different O—H⋯O bonds to form an infinite chain where two centrosymmetric dimeric motifs can be distinguished.     

An anomalous course of the reduction of 2‐(3‐oxo‐3,4‐dihydro‐quinoxalin‐2‐yl)benzene diazonium salt. Synthesis of a new quinoxalino[1,2‐c][1,2,3]benzotriazine system

By diazotization of 3‐(2‐aminophenyl)quinoxaline‐2(lH)‐one la and 3‐(2‐aminophenyl)‐6,7‐dimethylquinoxaline‐2(lH)‐one 1b followed by the reaction with sodium sulphite new quinoxalino[1,2‐c]‐[1,2,3]benzotriazins 4a and 4b were prepared, respectively.     

2‐(4‐Bromophenyl)‐1,2‐dihydropyrimido[1,2‐a]benzimidazol‐4(3H)‐one and 4‐(4‐methylphenyl)‐3,4‐dihydropyrimido[1,2‐a]benzimidazol‐2(1H)‐one form hydrogen‐bonded base‐paired dimers

The title compounds, 2‐(4‐bromo­phenyl)‐1,2‐di­hydro­pyrimido­[1,2‐a]­benzimidazol‐4‐(3H)‐one, C₁₆H₁₂Br­N₃O, (IVa), and 4‐(4‐methylphenyl)‐3,4‐dihydropyrimido[1,2‐a]benzimidazol‐2‐(1H)‐one, C₁₇H₁₅N₃O, (Vb), both form R(8) centrosymmetric dimers via N—H?N hydrogen bonds. The N?N distance is 2.943 (3) Å for (IVa) and 2.8481 (16) Å for (Vb), with the corresponding N—H?N angles being 129 and 167°, respectively. However, in other respects, the supra­molecular structures of the two compounds differ. Both compounds contain different C—H?π interactions, in which the C—H?π(centroid) distances are 2.59 and 2.47 Å for (IVa) and (Vb), respectively (the latter being a short distance), with C—H?π(centroid) angles of 158 and 159°, respectively. The supramolecular structures also differ, with a short Br?O distance of 3.117 (2) Å in bromo derivative (IVa), and a C—H?O interaction with a C?O distance of 3.2561 (19) Å and a C—H?O angle of 127° in tolyl system (Vb). The di­hydro­pyrimido part of (Vb) is disordered, with a ratio of the major and minor components of 0.9:0.1. The disorder consists of two non‐interchangeable envelope conformers, each with an equatorial tolyl group and an axial methine H atom.     

Reactions of 4,7‐dihydro‐1,2,4‐triazolo[1,5‐a]pyrimidines with α,β‐unsaturated carbonyl compounds

The reaction of 5,7‐diphenyl‐4,7‐dihydro‐1,2,4‐triazolo[1,5‐a]pyrimidine ( 1 ) with α,β‐unsaturated carbonyl compounds 2a‐f led to the formation of the alkylated heterocycles 3a‐f (Figure 1). However, the reaction of 5‐methyl‐7‐phenyl‐4,7‐dihydro‐1,2,4‐triazolo[1,5‐a]pyrimidine ( 5 ) with 2a‐c yielded under the same conditions the triazolo[5,1‐b]quinazolines 6a‐c (Figure 3). In this case, the alkylation is followed by a cyclocondensation. The structure elucidation of the products is based on ir, ms, ¹H and ¹³C nmr measurements and on an X‐ray diffraction study.