Reactivity of the A-CH=N-NR-CX-B system. 4-Methyl-5-hydroxy-5-phenyl-(or thienyl)-2,3,4,5-tetrahydro-1,2,4-triazin-3-ones and their ring contraction products

The behaviour of some monosemicarbazones of phenyl- ( 1a-c ) and thienyl-glyoxal ( 2a-c ) towards cyclizing agents has been investigated. Upon aqueous sodium hydroxide treatment, 4-melhyl-semicarbazones 1a and 2a gave the addition products 3 and 4 , respectively, whereas the 2-methyl- and 2,4-dimethyl derivatives 1b,c and 2b,c gave demolition products only. On the other hand, compounds 1b,c gave the addition product 8 and the triazine 7 , respectively, on treatment with aqueous hydrochloric acid. Bromination of 1a,b gave the bromosemicarbazone 10a and a mixture of 10b and 9 , respectively. Performing the same reaction on 3 and 4 at 115°, the 1,3,4-oxadiazoles 13 and 14 have been obtained. The behaviour of bromosemicarbazones [ 10a,b ] and of the bromo-tetrahydrotriazine 9 towards heating or treatment with base has also been investigated.     

Reactivity of the A-CH=N-NR-CX-B system. 4-R-5-hydroxy-5-phenyl-2,3,4,5-letrahydro-1,2,4-triazine-3-thiones

The behaviour of phenylglyoxal thiosemicarbazones towards aqueous sodium hydroxide have been studied. Examples of addition compounds, 5-hydroxy-5-phenyl-2,3,4,5-tetrahydro-1,2,4-triazine-3-thiones, are reported.     

Palladium-catalyzed cyclization reactions of 3-propargylthio 1,2,4-triazin-5(2h)-ones to thiazolo-1,2,4-triazinones

Selective transformation of 3-propargylthio-1,2,4-triazin-5(2H)-ones ($\text{1}$) to 6-methylene-6,7-dihydro-4H-thiazolo[2,3-c][1,2,4]-triazin-4-ones ($\text{2}$) and 3-methylene-2,3-dihydro-7H-thiazolo[3,2-b]-[1,2,4]triazin-7-ones ($\text{3}$) is performed under the conditions of Pd(II) salt or sodium hydroxide catalysis, respectively.     

1,4,5,6-Tetrahydro-1,2,4-triazin-6-ones and 3-amino-1-imidazolin-4-ones from 2-aminoacylhydrazines

The 2-aminoacylhydrazines form 1,4,5,6-tetrahydro-1,2,4-triazin-6-ones with orthoesters and iminoesters. Benzylidene and isopropylidene derivatives of the 2-aminoacylhydrazines give the corresponding derivatives of 3-amino-1-imidazolin-4-ones with the same reagents.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1388–1391, October, 1991.     

Reactivity of the A-CH=N=NR-CX-B System. 1,3,4-thiadiazoles and Δ2 -thiadiazolines

The reactivity of the - system towards ferric chloride has been investigated. The cyclo-oxidation reaction led to the formation of 2-amino-5-thenoyl-1,3,4-thiadiazoles and 4-methyl-5-imino-2-thenoyl-Δ²-1,3,4-thiadiazolines. Their structures were proven spectro-scopically and chemically (nucleophilic attack and formation of the related 2-amino-1,3,4-thiadiazoles and 4-methyl-5-imino-Δ²-1,3,4-thiadiazolines).     

Synthesis of 4-Amino-6-R-4,5-dihydro-3-phenacylthio-1,2,4-triazin-5-ones and 8H-3-R-7-Aryl-1,2,4-triazino[3,4-b][1,3,4]thiadiazin-4-ones

A study was carried out on the reaction of 4-amino-6-R-2,3,4,5-tetrahydro-3-thioxo-1,2,4-triazin-5-ones with halo ketones in alkaline media to yield 4-amino-6-R-4,5-dihydro-3-phenacylthio-1,2,4-triazin-5-ones, which then convert to 8H-3-R-7-aryl-1,2,4-triazino[3,4-b][1,3,4]thiadiazin-4-ones.     

α–γ transition in nylon 6

The α to γ transition that occurs in nylon 6 upon iodine treatment was investigated by infrared spectroscopy, differential thermal analysis, and x-ray diffraction techniques. Thin films of nylon (0.2 mil) were treated in either iodine–potassium iodide aqueous solution or in iodine vapor. Very short treatment times, in the order of 30 sec, were found to effect the transition when a solution 0.5M with respect to iodine was used. The infrared spectra of the iodine nylon complexes formed from either the α- or γ-nylon 6 treated in vapor or dissolved iodine were all similar. This is an indication that molecular iodine is the active species in forming the complex. The temperature of the washing solution used to remove the iodine from the nylon determines whether an α-nylon 6 or γ-nylon 6 is obtained from the complex after washing. Nylon 6 plaque surfaces and thin films are similar in their behavior towards the iodine treatment. The γ-nylon 6 is a stable modification at all temperatures below its melting point. The conversion of the γ form back to the α modification can occur only if the hydrogen bonding is severely affected, e.g., by phenol treatment, iodine treatment, melting, etc. Infrared spectroscopy provided no evidence for an α–γ transition in nylon 6 on heating the sample continuously through its melting point. The shapes of the melting peaks in the above two modifications of nylon 6 were sufficiently different to provide a means of identifying the two crystalline forms.     

Asymmetric induction in the reactions of 3-aryl-1,2,4-triazin-5(4H)-ones with C-nucleophiles

3-Aryl-1,2,4-triazin-5(4H)-ones, in the presence of N-protected amino acids, react with C-nucleophiles to form 1-acyl-6-Nu-3-aryl-1,6-dihydro-1,2,4-triazin-5(4H)-ones in high diastereomeric excess. This is the first case of the use of amino acids as chiral auxiliaries in nucleophilic additions to triazinones.     

Amino acids in the synthesis of heterocyclic systems. Synthesis of γ-(5-(1,2,4-Triazinylidene))-α,β-dehydro-α-amino acid derivatives and 6H-pyrido[1,2-d][1,2,4]triazin-6-ones

5-(1,2,4-Triazinyl) substituted enamines 3 react with 5(4H)-oxazolones 4 in acetic anhydride to give acetylated products 5 , while in toluene-acetic acid mixture nonacetylated products 9 are formed. Both types of products were isolated as (E,Z) mixtures. Compounds 5 and 9 rearrange into 6H-pyrido[1,2-d]-[1,2,4]triazin-6-ones 12 by heating in formic acid or in xylene, respectively. Compounds 5 are transformed in the presence of nucleophiles, such as sodium alkoxides or sodium amides via anionic form 10 into corresponding esters 13 and amides 14 of γ-(5-(1,2,4-triazinylidene)) substituted derivatives of α-amino-2-butenoic acid, which exist in 2-(Z),4-(Z) form.     

Addition-rearrangement reactions of 5-amino-3-oxo-Δ4–1,2,4-thiadiazolines

Bond-switching rearrangement via hypervalent sulfur occurs during the reactions of 5-anilino-2-benzyl-3-oxo-Δ⁴–1,2,4-thiadiazoline 5 with electrophilic nitriles, isothiocyanates, carbon disulfide and ketenes, yielding the products 6 and 7. In contrast, N,N'-ditolylcarbodiimide reacts with 5 to give the normal addition product 8 , which rearranges only partially to 9 in several solvents (chloroform, acetonitrile and dimethyl sulfoxide). The equilibrium position depends on the temperature, favoring 9 at higher temperatures.     

Collision-induced dissociation study of cyclization of α-diazo-ω-arylsulphonylaminoalkan-2-ones

The collision-induced dissociation mass-analysed ion kinetic energy (CID MIKE) spectra (electron impact and chemical ionization) of five α-diazo-ω-arylsulphonylaminoalkan-2-ones and corresponding N-arylsulphonylazetidin-3-ones and N-arylsulphonylpyrrolidin-3-ones were studied. The [M ? N₂]⁺˙ and [MH ? N₂]⁺ ions of two types of the diazo ketones provide CID MIKE spectra similar to those of the corresponding M⁺˙ and MH⁺ of the heterocyclic compounds, i.e. a cyclization analogous to that in solution takes place. For the other three types of diazo compounds the Wolff rearrangement prevails in both the gas and liquid phases. The effect of the substituents on the cyclization process was studied. The data obtained permit the results of acid-catalysed cyclization of similar diazo ketones to be predicted on the basis of their CID MIKE spectra. Chemical ionization provides a closer similarity with reactions in solution than electron impact ionization, which can be rationalized by the protonation of the diazo ketone molecule being the driving force of the cyclization reaction either in solution or in the ion source of a mass spectrometer.     

Synthesis of isobornylphenol-containing 3-aryl-1,2,4-triazin-5(4<Emphasis Type="Italic">H</Emphasis>)-ones

A method for modification of 3-aryl-1,2,4-triazin-5(4H)-ones with isobornylphenols was proposed. The influence of various acylating agents on the reaction pathway was studied.     

Palladium-catalyzed polyhetero-claisen rearrangement of 4-allylthiopyrimidin-2(1h)-ones and 5-allylthio-1,2,4-triazin-3(2h)-ones

The S → N allylic transposition of 4-allylthiopyrimidin-2(lH)-ones 4 and 5-allylthio-1,2,4-triazin-3(2H)-ones 5 has been performed successfully by catalysis of palladium(II) salts. In both cases the N-alkylated products (6 and 7) are obtained with no traces of the C-alkylated products.     

Δ3- and Δ4-1,2,4-oxadiazolin-5- and 3-ones

Preparations for 2,3-diphenyl- and 2-benzyI-3-phenyl-Δ³-1,2,4-oxadiazolin-5-ones (3) and (4) and for 2,5-diphenyl-Δ⁴-1,2,4-oxadiazolin-3-one ( 7 ) are reported.