吲哚-4-甲醛的合成新方法

以2-甲基-3-硝基苯甲酸甲酯为原料,经硼氢化钠还原和铬酐-吡啶络合物氧化制得2-甲基-3-硝基苯甲醛(2),2用乙二醇保护醛基,经DMFDMA缩合、RaneyNi-水合肼环化、稀盐酸酸解等反应合成了吲哚4-甲醛(4),4及中间体的结构经^1H NMR确证。     

Synthesis of pyrazolone derivatives—XXI : On the reduction of 1-methyl-2-phenyl-1,2,3,10-tetrahydro-4H-pyrazolo[3,4-c][1] benzothiepin-3,4-dione with sodium borohydride

The selective reduction of α,β-unsaturated ketones and CC double bonds of pyrazolo[3,4-c][1]benzothiepins with sodium borohydride was studied. The reduction of 1-methyl-2-phenyl-1,2,3,10-tetrahydro-4H-pyrazolo[3,4-c][1]benzot (1) with sodium borohydride in refluxing methanol gave 1-methyl-2-phenyl-1,2,3,10-tetrahydro-4H-pyrazolo[3,4-c][1]benzothiepin-3-one (2). The mechanism of this unusual reaction in which the heterocyclic ketone was reduced to the corresponding methylene grouping with such a reagent was elucidated by the isolation of the following intermediates: 1-methyl-2-phenyl-1,2,3,3a, 10, 10a-hexahydro-4H-pyrazolo[3,4-c][1]benzothiepin-3,4-dione (6) and 1-methyl-2-phenyl-1,2,3,3a,10,10a-hexahydro-4H-pyrazolo[3,4-c][1]benzothiepin-3-one (4).     

1,2,4-Triazines. 8. Reduction of 4-methyl-1,2,4-triazin-5(4H)-ones with sodium borohydride. Regioselective preparation of dihydro-1,2,4-triazin-5(4H)-ones

Reduction of 3-methylthio-1,2,4-triazin-5(4H)-one ( 1a ) with sodium borohydride afforded 3-methylthio-1,6-dihydrotriazin-5(4H)-one ( 2b ) selectively. 3-Methylthio-6-t-butyl-1,2,4-triazin-5(4H)-one ( 1d ) reacted with sodium borohydride to give mainly 6-t-butyl-2,3-dihydro-1,2,4-triazin-5(4H)-one ( 3d ). The reaction of various 4-methyl-1,2,4-triazin-5(4H)-ones with sodium borohydride and the influence of bulkiness and electronic effect of the substituents at the 3- and 6-positions upon the product ratio, are also discussed.     

Borane complexes of 2-(1-Methyl-1,2,5,6-tetra-hydropyridin-3-yl)benzoxazoles

2-Pyridin-3-ylbenzoxazoles were synthesized by the reaction between 3-pyridinecarboxaldehyde and substituted o-aminophenols in the presence of iodobenzene diacetate. The resulting benzoxazoles 3 were treated with methyl iodide to give the corresponding pyridinium salts 4 which underwent the hydride reduction with sodium borohydride or sodium cyanoborohydride to produce 2-(1-methyl-1,2,5,6-tetrahy-dropyridin-3-yl)benzoxazole borane complex derivatives.     

Chemical and electrochemical reduction of some pyrazolo[1,5-a]pyrimidines

Various pyrazolo[1,5-a]pyrimidines 1 are prepared by two different ways. Their chemical reduction by sodium borohydride leads generally to 4,5,6,7-tetrahydro compounds 3, while lithium aluminum hydride yields 4,7-dihydro derivatives 2 at room temperature, and 3 in refluxing tetrahydrofuran. A complex mixture of oxidizable hydrodimers is obtained by electrochemical reduction. An electroreduction at a more negative potential also gives 4,7-dihydro compounds 2. A new 4,5-dihydropyrazolo[1,5-a]pyrimidine has been obtained by condensation of 5-amino-3-methyl-1H-pyrazole with acetophenone.     

A new direct synthesis of cinnamic acids from aromatic aldehydes and aliphatic carboxylic acids in the presence of sodium borohydride

Cinnamic acids have been prepared in 59-86% yields by a new direct synthesis from aromatic aldehydes and aliphatic carboxylic acids in the presence of sodium borohydride and N-methyl-2-pyrrolidinone (NMP) as solvent, at reflux (185-190°C), for 9-12 hours. Without sodium borohydride, this reaction is not possible.     

Chemical transformations of 3-aminopyrrolidin-2-ones of the norbornane and cyclopropane series

3-Aminopyrrolidin-2-ones containing a fused norbornane or spirocyclopropane fragment react with benzaldehyde to give azomethines, which can be transformed into N-substituted 3-aminopyrrolidin-2-ones by reduction with sodium borohydride. Diazotization of amino-pyrrolidinones with NaNO₂ in acetic acid results in the elimination of molecular nitrogen and in the formation of acetoxy or unsaturated derivatives (through stabilization of intermediate carbocations). 6-Methylidene4-azaspiro[2.4]heptan-5-one obtained by diazotization of 6-amino-6-methyl-4-azaspiro[2.4]heptan-5-one easily reacts with diazomethane, diazocyclo-propane, and benzonitrile oxide to yield heterocyclic spiranes by means of 1,3-dipolar cycloaddition.     

Reduction of 4-arylidene-1,3-(2H,4H)isoquinolinediones

Catalytic hydrogenation of some 4-arylidene-1,3-(2H,4H)isoquinolinediones (1) afforded the corresponding 4-arylmethyl-1,3-(2H,4H)isoquinolinediones (2) , but reduction of 1 by sodium borohydride gave 4-arylmethyl-1(2H)isoquinolones (isocarbostyrils, 3). Compounds of type 1 studied had aryl substituents phenyl, 3,4-dimethoxyphenyl, 3,4-methyleneoxyphenyl and 2-furyl. In one example of sodium borohydride reduction of an N-methylisoquinolinedione derivative (1) the heterocylic ring was opened, and 2-(1-hydroxymethyl-2-phenylethenyl)-N-methylbenzamide (4) was obtained from 4-benzylidene-2-methyl-1,3-(2H,4H)isoquinolinedione.     

Recyclization and photorearrangements of 2-acetyl-4,4-dialkyl-2-buten-4-olide oximes

Recyclization to derivatives of dihydro-1,2-oxazines was realized by the reaction of 2-acetyl-3-methyl-4,4-dialkyl-2-buten-4-olide oximes with sodium borohydride. The UV-irradiation-initiated Beckmann rearrangement of the oximes cited above leads to 4,4-dialkyl-2-buten-4-olide-2-carboxylic acid N-methylamides.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 157–160, February, 1989.     

Synthesis of 2-(3-hydroxy-2-methyl-1-alkenyl)-1-pyrrolines and 2-(3-hydroxybutyl)-1-pyrroline using α-lithiated 2-methyl-1-pyrroline

Condensation of 2-methyl-1-pyrroline with chloroacetone or 3-chloro-2-butanone using LDA in THF afforded novel 2-(3-hydroxy-2-methyl-1-alkenyl)-1-pyrrolines via a peculiar reaction mechanism instead of the anticipated 2-(3-oxobutyl)-1-pyrrolines. The intermediacy of 2-(2,3-epoxy-2-methylalkyl)-1-pyrrolines in the latter transformation was demonstrated by immediate reductive epoxide ring opening utilizing lithium aluminium hydride in diethyl ether. Furthermore, 2-(3-oxobutyl)-1-pyrroline was prepared via an alternative approach through alkylation of 2-methyl-1-pyrroline with 3-chloro-2-(methoxymethyloxy)-1-propene using LDA in THF, followed by acid hydrolysis. Reduction of 2-(3-oxobutyl)-1-pyrroline by sodium borohydride in methanol afforded the corresponding 2-(3-hydroxybutyl)-1-pyrroline in good yield.     

New simple laboratory method for the synthesis of pirazidol

5,6-Dihydro-8-methyl-4H-pyrazino[3,2,1-j,k]carbazole was obtained by the reaction of -bromoacetaldehyde dibutylacetal, ammonium acetate, and 1,2,3,4-tetrahydro-6-methyl-1-ketocarbazole in acetic acid. The reduction of 5,6-dihydro-8-methyl-4H-pyrazino[3,2,1-j,k]carbazole or its hydrochloride with sodium borohydride leads to 2,3,3a,4,5,6-hexahydro-8-methyl-1H-pyrazino[3,2,1-j,k]carbazole hydrochloride — the medicinal preparation pirazidol.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1362–1363, October, 1983.     

Investigation of the selective reduction of isatin derivatives. Synthesis of α-hydroxyacetophenone derivatives and ethyl spiro-3,3-(ethylenedioxy)-2-hydroxyindoline carboxylates

The product from the reduction of ethyl spiro-3,3-(ethylenedioxy)-2-oxindole carboxylates (1) using borohydride salts has been found to be dependant upon both solvent and metal ion. With polar solvents and lithium bromide/sodium borohydride, spiro-3,3-(ethylenedioxy)-2-hydroxyindole carboxylates (2) are obtained in high yields whilst [2-(2-hydroxymethyl-[1,3]dioxolan-2-yl)-phenyl]-carbamic acid ethyl esters (3) are obtained using sodium borohydride in less polar solvents.     

苷类化合物研究(Ⅰ)——天麻苷类似物的合成

本文合成了16种天麻苷类似物,测定了它们的¹³CNMR和¹HNMR。依据NMR数据,这些化合物的端基构型指定为β构型。     

P-N compounds. 30. Phosphaminimides. 5. N-phosphinylimino-1,2,5,6-tetrahydropyridines

N-[ (Diethoxyphosphinyl)imino] and N-[ (diphenylphosphinyl)imino]-5-methyl-1,2,5,6-tetrahydropyridines were prepared by sodium borohydride reduction of the corresponding pyridinium and 3-methyl pyridinium inner salts. The carbonyl analog of this latter precusor was resynthesized and its structure completely verified.     

Condensed isoquinoline. 5. Reaction of the 6-methyl-5-oxoisoquino[2,3-a] Quinazolinium cation with certain nucleophiles

It has been shown that nucleophilic reagents react with the 6-methyl-5-oxoisoquino[2,3-a]quinazolinium cation at the C₍₂₎ atom. The structure of the reaction product is determined by the type of reagent. On reaction with sodium borohydride and secondary amines, 12H- and 12-dialkylamino-12H-6-methyl-5-oxo-5, 6-dihydroisoquino[2,3-a]quinazolines are formed. In the case of primary amines the reaction is accompanied by fission of the C₍₁₂₎-N_(t3) bond with the formation of 2-[o-(N-alkylformimidoyl)-benzyl]-3-methyl-4-oxoquinazolines.See [1) for the preceding communication.T. G. Shevchenko Kiev University, Kiev 252017. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 522–526, April, 1995. Original article submitted March 24, 1995.     

NaBH_4还原二氟乙酸乙酯合成二氟乙醇的研究

采用硼氢化钠(NaBH4)还原二氟乙酸乙酯(CF2HCOOCH2CH3)合成二氟乙醇(HCF2CH2OH)。探讨NaBH4用量、溶剂、反应温度和反应时间等因素对反应的影响。实验结果表明:在投料比n(NaBH4)/n(CF2HCOOCH2CH3)=0.6,乙醇为溶剂,温度0℃反应条件下,二氟乙醇的收率可以达到98.1%。在极性溶剂中,随着反应温度的升高(5℃及以上),NaBH4的分解加剧,低温对反应有利。     

2-甲基-6-溴苯并碲唑及其衍生菁染料的合成

以对溴苯胺为原料,经汞化、酰化,再与四氯化碲发生亲电取代反应生成2-乙酰氨基-5-溴苯基三氯化碲(内盐);后者以硼氢化钠还原、浓盐酸关环,用碳酸氢钠中和后即得关键中间体2-甲基-6-溴苯并碲唑。苯并碲唑经碘甲烷或碘乙烷季铵化后,用原甲酸三乙酯缩合制得相应的对称染料2,2'-二甲基-5,5'-二溴碲碳菁碘盐和2,2'-二乙基-5,5'-二溴碲碳菁碘盐。测定了它们的可见吸收光谱。     

Synthesis of azepinoquinazoloncs from 2-methyl-3-(o-tolyl)-4-quinazolone

Some new azepinoquinazolones were synthesized from 2-methyl-3(o-tolyl)-4(3H)quinazolone (metliaqualone )as potential hypnotic agents. Methaqualone (I) reacted with dimethyl acetylene-dicarboxylate (dmad) to give the azepinoquinazolone (II) which on treatment with PPA gave the pentacyclic ketone (V). Subsequent sodium borohydride reduction of the ketone (V) gave the fused azepine (VIa). Reaction of the azepinoquinazolone (II) with formic acid resulted in cleavage of the quinazolone nucleus to give the azepine (VIII). None of the compounds synthesized exhibited significant hypnotic activity.     

Condensed pyridazines. Part IV. Reductive cyclization of (Z)-methyl 3-(6-azido-3-chloro-1-methyl-4-oxo-1,4-dihydropyridazin-5-yl)-2-rnethylacrylatc (I) to pyrido[2,3-c] pyridazines and the acid-catalysed cyclization of I to a pyrano[2,3-d] pyridazine

Reduction followed by cyclization of (Z)-methyl 3-(6-azido-3-chloro-1-methyl-4-oxo-1,4-dihydropyridazin-5-yl)-2-methylacrylate (I) to pyrido[2,3-c]pyridazines by treatment with triethyl phosphite or hydrazine hydrate as the reducing agents is described. Compound I was also reductively cyclized with sodium borohydride. Treatment of I with concentrated sulfuric acid gave 8-chloro-3,6-dimethyl-2,5-dioxo-5,6-dihydro-2H-pyrano[2,3-d] pyridazine (VII) which also could be synthesized by another independent route. A mechanism for the cyclization is proposed.     

Synthesis and antimicrobial testing of 2-amino-6-hydroxymethyl-4-(3H)pyrido[3,2-d]pyrimidinone

Synthesis of 2-amino-6-hydroxymethyl-4-(3H)pyrido[3,2-d]pyrimidinone ( 5 ) from 2-amino-6-methyl-4-(3H)-pyrido[3,2-d]pyrimidinone ( 2 ) was accomplished by selenium dioxide oxidation of 2 to the aldehyde 4 followed by sodium borohydride reduction. Compound 2 was available in four steps from 5-aminouracil or in two steps from 5-nitroisocytosine ( 3a ). Catalytic reduction of 4 or 5 gave a mixture of 2-amino-6-methyl-5,6,7,8-tetrahydro-4-(3H)pyrido[3,2-d]pyrimidinone ( 6a ) and the 6-hydroxymethyl compound 6b . These compounds showed only weak inhibitory activity in the coupled reactions catalyzed by 7,8-dihydro-6-hydroxymethylpterin pyrophosphokinase and 7,8-dihydropteroate synthetase from E. Coli. No significant antibacterial activity was observed.