Functionalization of the pyridazin-3(2H)-one ring via palladium-catalysed aminocarbonylation

5-Iodo- and 4,5-dibromo-2-methylpyridazin-3(2H)-ones were aminocarbonylated in the presence of various amines including amino acid methyl esters in a palladium-catalysed reaction. The iodo derivative afforded the corresponding amides with complete conversion and high isolated yields. The dibromo derivative has shown unexpectedly high reactivity in this reaction, resulting in 4,5-dicarboxamides using primary amines as N-nucleophiles. Monoaminocarbonylation has not been observed, i.e., neither 4-bromo-5-carboxamide nor 4-carboxamido-5-bromo derivatives have been formed. However, the use of secondary amines such as piperidine and morpholine resulted in the formations of mixtures of amino-substituted bromopyridazinones. That is, no carbon monoxide insertion took place in these cases. Some mechanistic details of the formation of aminocarbonylation and amination products are also discussed.     

1,3-Dipolar cycle-addition of 2-diazoalkanes to pyridazin-3(2H)-one derivatives. The formation of 3H-pyrazolo[3,4-d]pyridazin-4(5H)-one and 3H-pyrazolo[3,4-d]pyridazin-7(6H)-one derivatives

1,3-Dipolar cycloadditions of diazoalkanes to pyridazin-3(2H)-ones 1–7 and pyridazin-3(2H)-thiones 8 and 9 are regioselective producing 3H -pyrazolo[3,4-d]pyridazin-4(5H)-ones 15–19, 27–29 and 34–38 as the major products. In some instances, the isomeric 3H-pyrazolo[3,4-d]pyridazin-7(6H)-ones, such as 20 and 23 were isolated as the minor products. From 3 and 6 the primary 3a,7a-dihydro cycloadducts 25 and 26 , and rearranged 1,2-dihydro intermediate 31 were isolated. From 10 and 1-diazoindane the isomeric exo- and endospiro products 39 and 40 were formed.     

Functionalized heteroarylpyridazines and pyridazin-3(2H)-one derivatives via palladium-catalyzed cross-coupling methodology

A general method for the synthesis of functionalized pyridazinylboronic acids/esters is described involving a directed ortho metalation (DoM)--boronation protocol (Schemes 1 and 2). A comprehensive study of the reactivity of the C-B bond in palladium-catalyzed cross-couplings with aryl/heteroaryl halides is presented. Aryl-/heteroarylpyridazines are thereby obtained in synthetically viable yields (typically 40-75%) although in some cases competing protodeboronation has been observed. A series of pyridazin-3(2H)-one derivatives, including 4,6-diaryl/heteroaryl derivatives, have been obtained from the corresponding 3-methoxypyridazines in straightforward procedures (Schemes 3 and 4). Several X-ray crystal structures of aryl-/heteroarylpyridazines and derived pyridazin-3(2H)-one derivatives are reported. These multi-ring systems are of considerable interest in contemporary N-heterocyclic chemistry.     

6-甲基-4-(3-三氟甲基苯基)-3(2H)-哒嗪酮的合成与生物活性研究

在对3-三氟甲基-1,1'-联苯类衍生物类化合物进行CoMFA计算的基础上,设计合成了化合物6-甲基-4-(3-三氟甲基苯基)-3(2H)-哒嗪酮(T-1),分别采用小杯法、浮萍法和盆栽法对其除草活性进行了较详细的研究,发现化合物T-1具有很好的白化活性和除草效果.研究了T-1的合成路线,实施了三条完全不同的路线进行合成,比较了三条路线的优缺点.     

Synthesis of (hetero)arylated pyridazin-3(2H)-ones via Negishi reaction involving zincated pyridazin-3(2H)-ones

Zincated pyridazin-3(2H)-ones generated via bromine-magnesium exchange followed by transmetalation using ZnCl(2) or via lactam-directed ortho C4-H zincation with TMPZnCl·LiCl have been synthesized. These in situ created organometallics can be used in Negishi reactions with iodo(hetero)arenes delivering a new approach toward (hetero)arylpyridazin-3(2H)-ones.     

New, simple and versatile synthesis of 4,6-disubstituted pyridazin-3(2H)-ones

A simple, two-step synthesis of 4,6-disubstituted pyridazin-3(2H)-ones starting from 2-diethoxyphosphoryl-4-oxoalkanoates and hydrazines is described. The intermediate 4-diethoxyphosphoryl-4,5-dihydropyridazin-3(2H)-ones obtained in this way are used in a Horner-Wadsworth-Emmons olefination of aldehydes to give a variety of disubstituted pyridazin-3(2H)-ones.     

One-pot synthesis of 3-(2-cyanophenyl)quinazolin-4(3H)-one

Anthranilonitrile reacting with formic acid at room temperature for three days gave 64% of 3-(2-cyanophenyl)quinazolin-4(3H)-one. Under similar conditions anthranilic acid. 4-nitroaniline, and 2,5-dichloroaniline were N-formylated in good yields.Institute of Organic Chemistry and Technology, Silesian Technical University, Krzywoustego, 4, 44–100 Gliwice, Poland; e-mail: wojtex@zeus.polsl.gliwice.pl. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 922–924, July, 2000.     

New synthesis of 4,5-dihydro-1,2,4-triazin-3(2H)-one derivatives through cyclic transformation of 1,3,4-oxadiazol-2(3H)-one derivatives

Some 5-aryl(or benzyl)-2-oxo-1,3,4-oxadiazole-3(2H)-acetones or acetophenones 2 were easily prepared. These compounds reacted with hydrazine derivatives to give 4,5-dihydro-1,2,4-triazin-3(2H)-one derivatives 3 , 4 and 6 in good yields. With phenylhydrazine, the intermediate hydrazones 5 were obtained. Their conversion into triazinones necessitated the presence of sodium ethylate.     

Straightforward three-component synthesis of diarylmethylpiperazines and 1,2-diarylethylpiperazines

Several functionalized diarylmethylpiperazines and 1,2-diarylethylpiperazines have been synthesized in moderate to high yield according to a one-step three-component coupling between an aromatic or a benzylic organozinc reagent, a piperazine derivative, and an aromatic aldehyde. The procedure can be extended to the synthesis of benzylpiperazine derivatives or β-arylethylpiperazines toward the use of paraformaldehyde or aliphatic aldehydes.     

Facile isocyanide-based one-pot three-component regioselective synthesis of highly substituted pyridin-2(1H)-one derivatives at ambient temperature

A novel one-pot three-component regioselective synthesis of highly substituted pyridin-2-one derivatives starting from simple and readily available starting materials is described. The reactive zwitterionic intermediate generated by the addition of an isocyanide to dimethyl acetylenedicarboxylate (DMAD) was trapped with N-arylidene-2-cyanoacetohydrazides to afford the title compounds in moderate to good yields at room temperature without using any catalyst and other additives.     

Benzoxazol-2 (3H)-one and 1,3,4-oxadiazol-2(3H) -one derivatives from substituted enaminones and ketoenamines

Enaminones and ketoenamines bearing a hydrazine type substituent undergo side chain thermal cyclization, the former into benzoxazol-2 (3H)-one derivatives and the latter into 1, 3, 4-oxadiazol-2 (3H)-one derivatives. Factors affecting such reactions are discussed.     

Biomimetic synthesis of 4-acetylbenzoxazolin-2(3H)-one isolated from Zea mays

4-Acetylbenzoxazolin-2(3H)-one has been prepared biomimetically during attempts to synthesize the hemiacetalic hydroxamic acid 5-acetyl-2,4-dihydroxy-2H-1,4-benzoxazin-3(4H)-one by the immediate degradation of this unstable compound generated as an intermediate. Thus, 4-acetylbenzoxazolin-2(3H)-one recently isolated from Zea mays kernels, and similar to other benzoxazolin-2(3H)-ones known from plant sources, is assumed to have originated from the degradation of natural 5-acetyl-2,4-dihydroxy-2H-1,4-benzoxazin-3(4H)-one which in turn could have been enzymatically released by a β-glucosidase from the corresponding 2-β-D-glucoside.     

3-亚甲基六氢苯并呋喃-2(3H)-酮的简便合成

以氧化环己烯为原料,在正丁基锂作用下与乙腈经开环反应制得2-羟基环己基乙腈(2);2依次经水解、内酯化、二甲胺甲基化、甲基化和Hofmann降解反应合成了α-亚甲基-γ-丁内酯类化合物--3-亚甲基六氢苯并呋喃-2(3H)-酮,总收率30.4%,其结构经¹H NMR,¹³C NMR和HR-MS(EI)确证。     

A convenient synthesis of nitro-substituted 1,2-benzisothiazol-3(2H)-one 1,1-dioxides (nitrosaccharins)

Nitro-substituted 1,2-benzisothiazol-3(2H)-one 1,1-dioxides (nitrosaccharins) have been synthesized by amminolysis of nitro 2-chlorosulfonylbenzoate esters. This method appears to have advantages over the original procedure of oxidation of an ortho-toluenesulfonamide.     

A facile and efficient approach for the synthesis of 3-arylthiazol-2(3H)-one

A facile and efficient method for synthesis of 3-arylthiazol-2(3H)-one through the reaction of acyl azide and 1,4-dithiane-2,5-diol was reported. This reaction proceeded at 80?°C at first and then in acidic condition at room temperature, to afford products in good yields for a wide range of substrates and a possible mechanism has also been proposed.     

Synthesis of functionalized pyridazin-3(2H)-ones via nucleophilic substitution of hydrogen (SNH)

Reaction of 2-benzyl-5-halopyridazin-3(2H)-ones (3) with Grignard reagents followed by quenching with electrophiles unexpectedly yielded 4,5-disubstituted pyridazin-3(2H)-ones instead of 5-substituted pyridazin-3(2H)-ones. These reactions represent the first examples of cine substitution in which the anionic σ(H)-adduct is quenched by electrophiles (other than a proton) before elimination takes place. Insight into the reaction mechanism led to the direct transformation of 2-benzylpyridazin-3(2H)-one (7) and 2-benzyl-6-chloropyridazin-3(2H)-one (9) into the corresponding C-4 alkyl and aryl derivatives (when Br(2) was used as the electrophile).     

Synthesis of 5-Amino-4-imino-3,4-dihydropyrido[3,4-d]pyridazin-1(2H)-one Derivatives

Russian Journal of Organic Chemistry -     

4-Bromo-5-(4′-hydroxymethyltriazolyl)pyridazin-3-one and its derivatives

4-Bromo-5-(4-hydroxymethyltriazolyl)pyridazin-3-ones have been obtained for the first time by the reaction of 5-azido-4-bromopyridazin-3-ones with propargyl alcohol. They have been converted into 4-bromo-5-(4-halogenomethyltriazolyl)pyridazin-3-ones.