Silver-catalyzed cascade reaction of o-aminoaryl compounds with alkynes: an aniline mediated synthesis of 2-substituted quinolines

An efficient silver-catalyzed, aniline mediated cascade hydroamination/cycloaddition of o-aminoaryl compounds including o-aminoaryl aldehydes, o-aminoaryl ketones with alkynes for the synthesis of 2- or 2,4-substituted quinolines is reported. The reactions proceed with high regioselectivity to afford mono- or disubstituted quinoline derivatives in good to high yields using AgOTf as the catalyst in the air.     

Photo-Fries rearrangement of N-arylsulfonamides to aminoaryl sulfone derivatives

Photochemical reaction of variously substituted p-toluenesulfonanilides was studied. The reaction gives rearranged products, o- and p-amino-substituted diaryl sulfones with the combined yields of 38-72%: the p-isomer is more favored over the o-isomer with the selectivity ratio of 1.1-4.3 depending on the substituents. N-Alkylation of the sulfonanilides increases the yields of the rearranged products, and e-withdrawing substituents on the N-phenyl ring does not lower the yields drastically. This study provides simple methodology for the synthesis of o- and p-aminoaryl sulfones which are otherwise not easily accessible.     

Novel one-step synthesis of 2-carbonyl/thiocarbonyl isoindolinones and mechanistic disclosure on the rearrangement reaction of o-phthalaldehyde with amide/thioamide analogs

A rearrangement reaction of o-phthalaldehyde with urea/thiourea analogs or amides/thioamides under the catalysis of TMSCl (trimethylchlorosilane) is described, whereby a series of 2-carbonyl isoindolinones and 2-thiocarbonyl isoindolinones are afforded. This is the first time that the N-carbonyl/thiocarbonyl isoindolinones are synthesized in a single step from o-phthalaldehyde. Similar reactions using primary amines also proceed smoothly to give corresponding N-alkyl or N-aryl isoindolinones in this mild catalytic system. The mechanism of this kind of rearrangement is discussed based on new evidences observed from the ESI-MS time-interval monitoring of the full reaction course and deuterium exchange experiments.     

Synthesis,spectral and structural studies of a Mn(II) complex of [N′-(pyridine-4-carbonyl)-hydrazine]-carbodithioic acid ethyl ester and Mn(II) and Ni(II) complexes of [N′-(pyridine-4-carbonyl)-hydrazine]-carbodithioic acid methyl ester

The new complexes [Mn(Hpchce)₂(o-phen)], {2[Mn(pchcm)(o-phen)₂]}·7H₂O and [Ni(Hpchcm)(o-phen)₂]Cl·CH₃OH with [N′-(pyridine-4-carbonyl)-hydrazine]-carbodithioic acid ethyl ester (H₂pchce) and [N′-(pyridine-4-carbonyl)-hydrazine]-carbodithioic acid methyl ester (H₂pchcm) have been synthesized, containing o-phenanthroline (o-phen) as a coligand. These ligands and their complexes have been characterized by elemental analyses, IR, magnetic susceptibility and single crystal X-ray data. H₂pchce (2), [Mn(Hpchce)₂(o-phen)] (3) {2[Mn(pchcm)(o-phen)₂]}·7H₂O (4) and [Ni(Hpchcm)(o-phen)₂]Cl·CH₃OH (5) crystallized in the monoclinic system, space group Pc, C2/c, P21/n and P21/n, respectively. The (N, O) donor sites of the bidentate ligands chelate the Mn(II) and Ni(II) centers forming a five-membered CN₂OM ring. The resulting complexes are paramagnetic and have a distorted octahedral geometry.     

A novel cyclization reaction of o-carboxyphenyl and o-carbamoylphenyl sulfoxides : Formation of benzoxathiane,dihydrobenzothiazine and benzoisothiazoline derivatives

When o-carboxyphenyl or o-carbamoylphenyl sulfoxide was heated with a large excess of acetic anhydride at 100–130° for 1–3 h, 6-membered heterocyclic compounds, i.e., 3,1 - benzoxathian-4 - one and 2,3 - dihydro - 1,3 - benzothiazin - 4 - one, and a 5-membered heterocyclic compound, i.e., 1,2-benzoisothiazolin-3-one were obtained in good yield.Cyclization would take place by the initial intramolecular nucleophilic attack of either the sulfinyl O atom at ortho-carbonyl carbon or the N atom of the amide group at ortho-sulfinyl S atom to give a 5-membered cyclic acyloxysulfonium salt or aminosulfonium salt, which undergoes an intramolecular Pummerer rearrangement to afford the heterocyclic compounds.     

Photoinduced reactions—LXXI: Photorearrangement of 3-hydroxyflavones to 3-aryl-3-hydroxy-1,2-indandiones

3-Hydroxyflavones (1) were found to undergo a novel photorearrangement to 3-aryl-3-hydroxy-1,2-indandiones (2) which were characterized as o-phenylenediamine adducts, 1-aryl-1-hydroxy-11H-indeno[1,2-b]quinoxalines (3). To the contrary, 3-methoxyflavone underwent photochemical intramolecular hydrogen transfer. Photochemical reactivities of several other flavonoids were examined. It appears that the 5-hydroxyl H-bonded to the 4-carbonyl causes photoresistance in flavonoids.     

Synthesis and electron impact mass spectra of 3-substituted 2-acylaminoindazoles

3-Substituted-2-acylaminoindazoles 2 were prepared via oxidative cyclization of o-aminoaryl ketone acylhydrazones 1 with iodosobenzene diacetate. Their electron ionization mass spectra were recorded and in addition to the molecular ions show common fragmentation pathways corresponding to the [M-N₂]⁺, [M-NHCOX]⁺ and [M-COX]⁺ ions, with some influence on the skeletal fragmentation by different substituents.     

Cleavage of azoles—I: Synthesis of some triazolyloxazolines and triazolylbenzoxazones

Treatment of glycine, and o-aminobenzoic acid with 4-arylhydrazono-2-phenyl-2-oxazolin-5-ones effected the formation of the N-(1,5-diaryl-1H-1,2,4-triazolyl-3-carbonyl) derivatives of the amino acids. The triazolylcarbonylglycines were azlactonised with aromatic aldehydes to 4-arylidene-2-triazolyl-2-oxazolin-5-ones, which behaved similar to the 2-phenyl analogues towards the action of ammonia and amines. Cyclisation of the triazolylcarbonylanthranilic acids with acetic anhydride afforded 2-triazolyl-4H-3,1-benzoxazin-4-ones.     

The protonation of ortho-methoxy- and hydroxy-benzaldehydes in FSO3H?SbF5?SO2 solution

The protonation of o-methoxy- and o-hydroxy-benzaldehydes in FSO₃H? SbF₅? SO₂ solution was investigated by ¹H NMR spectroscopy. The formation of the Z-carbonyl protonated molecule is explained by intramolecular hydrogen bonding.     

Synthesis, spectral and X-ray structural studies of Ni(II) complexes of N′-acylhydrazine carbodithioic acid esters containing ethylenediamine or o-phenanthroline as coligands

The new complexes [Ni(Hbstbh)₂(en)] (1) and [Ni(Hpchce)(o-phen)₂]Cl·CH₃OH·H₂O (2) with N′-benzoyl hydrazine carbodithioic acid benzyl ester (H₂bstbh) and [N′-(pyridine-4-carbonyl)-hydrazine]-carbodithioic acid ethyl ester (H₂pchce) have been synthesized, containing ethylenediamine (en) or o-phenanthroline (o-phen) as coligands. The ligands and their complexes have been characterized by elemental analyses, IR, magnetic susceptibility and single crystal X-ray data. [Ni(Hbstbh)₂(en)] (1) and [Ni(Hpchce)(o-phen)₂]Cl·CH₃OH·H₂O (2) crystallized in the monoclinic and triclinic systems, space group C2/c and P-1, respectively. The (N, O) donor sites of the bidentate ligands chelate the Ni(II) center and form a five-membered CN₂ONi ring. The resulting complexes are paramagnetic and have a distorted octahedral geometry.     

Synthesis and characterization of oxadisilole-fused acridines,dioxatrisilole-fused acridines and benzo[b]acridines

Oxadisilole-fused acridines, dioxatrisilole-fused acridines and benzo[b]acridines were synthesized through nucleophilic additions and aromatization reactions of arynes with 2-aminoaryl ketones or 2-aminoaryl aldehydes in good yields at room temperature. The photophysical, redox and thermal properties of these compounds were characterized. These compounds show potential applications as strong deep-blue or green emitters for OLED because of high fluorescence quantum yields and good thermal stabilities.     

Zur Oxydation von14C-markierten Phenolen (Ligninmodellen) in wäßrig-alkalischer Lösung mit Sauerstoff

o-Methoxyphenols withp-side chains labelled with¹⁴C at the α-C-atoms were synthesized and mildly oxygenated in dilute aqueous NaOH (0.2n, 1–2 mole equivalents NaOH) at 70° C. Derivatives with α-C-atoms in different states of oxidation exhibit different reaction patterns. In contrast top-alkyl-substitutedo-methoxyphenols which dimerize too,o′-dihydroxybiphenyls, eliminations of side chains according to theDakin reaction could be observed in the case of α-carbonyl, and α-carbinol derivatives, respectively. The carbon dioxide formed in the course of oxidation of models labelled with¹⁴C in α-position proved to be inactive and does definitely not originate from α-C-atoms. Possible reaction mechanisms are discussed, and to the importance of these particular elimination reactions in lignin chemistry is referred to.     

Synthesis of functionally substituted isoxazole and isothiazole derivatives

Acylation of benzene and toluene with 5-phenyl- and 5-(p-tolyl)isoxazole-3-carbonyl chlorides gave 5-phenyl(or p-tolyl)isoxazol-3-yl phenyl(or p-tolyl)ketones which were reduced to the corresponding alcohols with sodium tetrahydridoborate in propan-2-ol. Selective reduction of the carboxy group in 4,5-dichloroisothiazole-3-carboxylic acid was achieved by the action of BH₃, and the aldehyde group in 4-formyl-2-methoxyphenyl 5-arylisoxazole-3-carboxylates and 4,5-dichloroisothiazole-3-carboxylates was reduced to hydroxymethyl group with sodium triacetoxyhydridoborate in benzene. Acylation of the resulting hydroxymethyl derivatives with 5-arylisoxazole- and 4,5-dichloroisothiazole-3-carbonyl chlorides afforded the corresponding esters containing two azole fragments in their molecules.     

An iodoacetamide-based free radical cyclisation approach to the 7,12-dihydro-indolo[3,2-d][1]benzazepin-6(5H)-one (paullone) system

A potentially versatile route to 2-(2-aminoaryl)indoles is described based on a palladium-mediated cyclisation of N-substituted indoles, together with free radical cyclisation of their N-benzyliodoacetamide derivatives to the 7,12-dihydro-indolo[3,2-d][1]benzazepin-6(5H)-one system.     

Reactions of ortho oxy-substituted benzyl and phenacyl bromides in dimethyl sulphoxide

o-Acetoxy- and o-benzoyloxy-benzyl bromides and tosylates oxidatively rearrange in moist dimethyl sulphoxide to o-hydroxybenzyl esters; o-acetoxy- and o-benzoyloxy- phenacyl bromides rearrange to mixtures of 2-hydroxycoumaran-3-ones and o-hydroxyphenacyl esters; o-hydroxyphenacyl bromides also yield 2-hydroxycoumaran-3-ones, together with o-hydroxyphenacyl alcohols. 2-Acetoxybenzaldehyde is reductively rearranged by sodium borohydride to o-hydroxybenzyl acetate.     

Silica sulfuric acid as an efficient catalyst for the Friedländer quinoline synthesis from simple ketones and ortho-aminoaryl ketones under microwave irradiation

The synthesis of quinoline derivatives via Friedländer method from ortho-aminoaryl ketones in the presence of a catalytic amount of silica sulfuric acid (SSA) under solvent-free condition and microwave irradiation was described. A good range of simple ketones such as cyclohexanone and deoxybenzoin were used.     

Synthesis of phthalascidin analogs

We report a new approach to obtain phthalascidin analogs. 6-Phthalimidomethylpyrazino[1,2-b]isoquinoline-1,4-dione (5a) was obtained in a one-pot N-alkylation/cyclization of the corresponding 1-acetyl-3-arylmethyl-2,5-piperazinedione with N-phthalylacetaldehyde dimethyl acetal. Chemoselective reduction of the C(1)-carbonyl group in the 3-arylmethyl-11,11a-dehydroderivative 9a was followed by cyclization of an acyliminium intermediate, to give the 6,15-imino-7-oxo-14,14a-dehydroisoquino[3,2-b]3-benzazocin 11a. Alternatively, the octacyclic compound 13a was obtained through a novel double cyclization of a precursor in which the C(1)-carbonyl and one phthalimide carbonyl group were reduced.     

Double cyclisation of phenylglycine-o-carboxylic acids—I: New stable mesoionic oxazolones

Remarkably stable mesoionic oxazolones possessing an oxazolo[3,2-a]quinolinium structure (5a–b),8,16, 17) were obtained by the double cyclisation of phenylglycine-o-carboxylic acids (3a–c) in refluxing acetic anhydride or in benzoic anhydride at 140°, The 0-Ac group was eliminated to give the corresponding lactones (6a–b) or replaced by O-Ts (7). IR stretching vibrations of the endo-carbonyl were in the range 1710–1768 cm^?1, while v_1-CH exhibited unusually high values (3159–3194 cm^-1). 1-Acyl derivatives could be obtained only with TFAA (23–24), although easy deuteration of the same position took place in the presence of traces of trifluoroacetic acid. Hydrolysis of 5b led to the α-quinolone-N-acetic acid 27a. In the case of 5a, hydrolysis was accompanied by self-acylation of the nucleophilic site at C-4 with formation of a dimeric acid 28a. The presence of an additional Me group in phenylalanine-o-carboxylic acid (36) activates the corresponding mesoionic oxazolone 37 so that 1-acylation becomes possible with formation of the fused oxazole 38 by the Dakin-West reaction. Temperature dependent magnetic non-equivalence of methylene protons has been observed in acids 3b-d and f and also in the 7-membered anhydride 48b.     

On the reaction of 3-bromo-2-nitrobenzo[b]thiophene with some ortho-substituted anilines: an analysis of the products of reaction and of their NMR and MS properties

The title reaction, carried out in DMF in the presence of triethylamine or potassium carbonate, has furnished the ‘expected’ 3-amino-2-nitrobenzo[b]thiophenes 2o together with the ‘unexpected’ 2-amino-3-nitrobenzo[b]thiophenes 3o, thus recalling the situation observed with other weak nucleophiles in the presence of non-nucleophilic bases. The effects (electronic as well as steric) of the ortho-substituent (OH, NH₂, OMe, Me, Et, F, Cl and Br) on the course of the reaction have been investigated, determining their influence on yields and product ratios (2o/3o). An analysis of ¹³C NMR and MS spectra of 2o and 3o has been carried out. Ab initio computations on 2of, 2oi, 3of and 3oi at DFT level have furnished informations on their geometry and stability in the gas phase, thus allowing to assign a role to their stability on the course of the reaction as well as on some EI-MS results.     

Poly(N-bromo-N-ethylbenzene-1,3-disulfonamide) and N,N,N′,N′-tetrabromobenzene-1,3-disulfonamide as efficient reagents for synthesis of quinolines

Poly(N-bromo-N-ethylbenzene-1,3-disulfonamide) [PBBS] and N,N,N′,N′-tetrabromobenzene-1,3-disulfonamide [TBBDA] were used as efficient reagents for the synthesis of quinolines in excellent yields from 2-aminoaryl ketones and carbonyl compounds under aqueous and solvent-free conditions.