Synthesis of 3-(2-chloro-5-nitroanilino and 4-nitroanilino)-1-(2,4,6-trichlorophenyl)-2-pyrazolin-5-ones

A new synthesis of 3-anilino-1-aryl-2-pyrazolin-5-ones in which the pyrazolinone ring is built via N? N bond formation is described. 2-Cyano-2′,4′,6′-trichloroacetanilide 1 was converted to imino ether hydrochloride 2 which was reacted with anilines in methanol to produce N-arylimino ether 3a,b. Reaction of these N-arylimino ethers with hydroxylamine gave N-arylamidoximes 4a,b . An 1,2,4-oxadiazol-5-one 6a was prepared from the N-arylamidoxime 4a and subjected to base-induced rearrangement. The desired 3-anilino-pyrazolinone 7a was obtained only in a very low yield. However, O-acetylation of the N-arylamidoximes 4a,b followed by acid-catalyzed ring closure and rearrangement in the presence of excess acetic anhydride gave a mixture of N-acetylanilinopyrazolinones (e.g. 10 ) and 4-acetyloxy-3-N-acetylanilinopyrazoles (e.g. 12 ) which upon acid hydrolysis afforded the 3-anilinopyrazolinones 7a,b in better yield.     

Polycondensed heterocycles. IV. synthesis of 1,4-dioxo-2,3,3a,4-tetrahydro-1H-pyrrolo[2,1-c][1,4]benzothiazine

A method for the synthesis of the title compound 3 consisted of an intramolecular cyclization in a stannic chloride catalyzed Friedel-Crafts reaction of N-(2-methylthiophenyl)-5-oxoproline chloride 10 , prepared by chlorination of the corresponding acid 9 obtained by hydrolysis of its ethyl ester 8 . Condensation of 2-methylthioaniline 4 with diethyl bromomalonate 5 afforded diethyl 2-methylthioanilinomalonate 6 which gave 8 either directly by reaction with ethyl acrylate or by alkylation with ethyl β-bromopropionate or ethyl acrylate and cyclization of resulting triethyl 2-(2-methylthio)anilino-2-carboxyglutarate 7 . This method was not convenient because of the poor yield of 3 (14%). On the other hand, cyclization of N-(2-mercaptophenyl)-5-oxoproline 14 with DCC and DMAP provided 3 in 45% yield. Oxidation with m-CPBA of the esters 11 and 8 , demethylation via the Pummerer rearrangement of the respective sulphoxides 12 and 17 with TFAA and oxidation with iodine of resulting N-(2-mercap-tophenyl)-5-oxoproline esters 13 and 18 gave the corresponding disulphides 16 and 19 . Hydrolysis of these latter compounds and reduction of the resulting bis[2-[2-(hydroxycarbonyl)-5-oxo-1-pyrrolidinyl]phenyl] disulphide 15 with sodium dithionite afforded the required 14 . Deprotection of t-butyl ester 13 with TFA at 55° to obtain 14 led to 3 in 42% yield. Finally the Pummerer rearrangement of N-(2-methylsulphinylphenyl)-5-oxo-proline 20 yielded the mixture of 14 and 15 .     

Syntheses of substituted 2-(l-methyl-2-imidazolyl)quinolines

Reaction of methyllithium with 1-methy1-2-imidazolecarboxaldehyde afforded the corresponding alcohol 2. Oxidation of compound 2 with manganese dioxide gave 2-acety1-1-methylimidazole ( 3 ). Using compound 3 and substituted isatins 4 , the corresponding quinoline-4-carboxylic acids ( 5 ) were prepared. The reaction of acid imidazolides of 5 with appropriate amines yielded the amides 6 . Carbamic acid esters 10 were prepared by the Curtius rearrangement in good yield. Substituted quinolin-4-amines 13 were obtained by the acid hydrolysis of compound 10 (R₁ = t-Bu). Alkylation of amines 13 with diakylaminoalkyl chlorides gave compounds 14 .     

Acid-Catalyzed Transformations of 2-(Phenylethynyl)isoborneol

2-(Phenylethynyl)isoborneol was synthesized by treatment of camphor with lithium phenylacetylide. Skeletal rearrangements of the title compound under the Ritter reaction conditions afforded a mixture of N-(4-phenylethynyl- and 4-benzoylmethyl-1,7,7-trimethylbicyclo[2.2.1]hept-2-yl)acetamides at a ratio of 8:3. The reaction of 2-(phenylethynyl)isoborneol with formic acid involved mainly Meyer-Schuster rearrangement instead of the expected Rupe rearrangement, and the major product was 2-(1,7,7-trimethylbicyclo[2.2.1]hept-2-ylidene)-1-phenylethanone. The minor product (∼6%) was 1-(2-hydroxy-1,7,7-trimethylbicyclo[2.2.1]hept-2-yl)-2-phenylethanone. The Ritter reaction of 2-(1,7,7-trimethylbicyclo[2.2.1]hept-2-ylidene)-1-phenylethanone selectively yielded N-(4-benzoylmethyl-1,7,7-trimethylbicyclo[2.2.1]hept-2-yl)acetamide.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 6, 2005, pp. 853–858.Original Russian Text Copyright © 2005 by Koval’skaya, Kozlov, Dikusar.     

Synthesis of pyrido[1,2-a]pyrimido[4,5-d]pyrimidin-5-ones. Cyclization reaction of 4-[(3-hydroxy-2-pyridyl)amino]-2-phenyl-5-pyrimidinecarboxylic acid with acetic anhydride

Treatment of 4-[(3-hydroxy-2-pyridyl)amino]-2-phenyl-5-pyrimidinecarboxylic acid (X) with acetic anhydride under refluxing conditions afforded 10-hydroxy-2-phenyl-5H-pyrido[1,2-a]-pyrimido[4,5-d]pyrimidin-5-one acetate (IX). The intermediate X was prepared from 4-chloro-2-phenyl-5-pyrimidinecarboxylic acid ethyl ester (V). The reaction of V with the sodium salt of 2-amino-3-hydroxypyridine at room temperature gave 4-(2-amino-3-pyridyloxy)-2-phenyl-5-pyrimidinecarboxylic acid ethyl ester (VI). Treatment of VI with a hot aqueous sodium hydroxide solution and subsequent acidification gave X. Involvement of 4-[(3-hydroxy-2-pyridyl)amino]-2-phenyl-5-pyrimidinecaroboxylic acid ethyl ester (VIII) (Smiles rearrangement product) as an intermediate in the above alkaline hydrolysis reaction of VI to X was demonstrated by the isolation of VIII and its subsequent conversion into X under alkaline hydrolysis conditions. Acetylation of VIII with acetic anhydride in pyridine solution gave 4-[(3-hydroxy-2-pyridyl)amino]-2-phenyl-5-pyrimidinecarboxylic acid ethyl ester acetate (XI), which afforded IX on fusion at 220°. This alternative synthesis of IX from XI supported the structural assignment of IX. Fusion of VI gave 10-hydroxy-2-phenyl-5H-pyrido[1,2-a]pyrimido]4,5-d]pyrimidin-5-one (VII). The latter was also obtained when VIII was fused at 210°. Acetylation of VII with acetic anhydride afforded IX.     

Structure and Thermal Behaviour of Methylcyclopentadiene Dimers

The mixture of isomeric dimethyl-endo-tricyclo[5.2.1.0^2,6]deca-3,8-dienes ( A ) resulting from Diels-Alder reactions of 1-, 2-, and 5-methylcyclopenta-1,3-dienes ( i – iii , respectively) at 20° was shown by GLC analysis to consist of at least 10 components (Table 1). The structures of the six major isomers 1 – 6 , representing 96% of the total mixture, were established by ¹H- and ¹³C-NMR spectroscopy. Whereas on heating up to 110° the proportions of 1 , 2 , 4 , and 6 remain nearly unaffected (±2 %), the dimers 3 and 5 , formed in 22 % and 24 % yield, respectively, at 20°, isomerise above 70° reversibly via [3,3]-sigmatropic rearrangement and equilibrate at 110° to a ca. 10:1 ratio.     

Synthesis and hydrolytic cleavage of 1-aryl-5-cyano-6-(2-dimethylaminovinyl)-4-oxo(thioxo)-1,4-dihydropyrimidines

1-Aryl-5-cyano-6-(2-dimethylaminovinyl)-4-oxo-1,4-dihydropyrimidines and their 4-thioxo analogs, which were prepared in three steps from cyanoacetamide and cyanothioacetamide, respectively, were subjected to hydrolysis. In aqueous AcOH, hydrolysis of N-(dimethylaminomethylene)-2-cyano-5-dimethylamino-2,4-pentadieneamide derivatives containing amino groups at position 3 afforded formylpyridones. The reaction of 2-cyano-3-dimethylaminothiocrotonamide with DMF dimethyl acetal gave rise to 3-cyano-4-dimethylamino-2-methylthiopyridine.     

Ring transformation of 4-amino and 4-N-(substituted)amino-1H-1,5-benzodiazepine-3-carbonitriles with hydroxylamine. A new synthesis of benzimidazolidine and isoxazole derivatives

The reaction of 4-amino-1H-1,5-benzodiazepine-3-carbonitrile 1 with hydroxylamine provided the ring-opened hydroxylamine adduct 2 which was converted to 2-benzimidazolidinylidene-3-hydroxyiminopropio-nitrile 4 in hydrochloric acid. The reaction of 4-ethoxycarbonylamino-1H-1,5-benzodiazepine-3-carbonitrile 6a or N-(3-cyano-1H,5-benzodiazepin-4-yl)-N′-ethylurea 6b with hydroxylamine afforded 5-(o-aminoanilino)-4-cyanoisoxazole 3 which underwent a facile rearrangement into 4 with a base.     

A new facile synthesis of 5-arninopyridazine-4-carboxylic acid

Hofmann rearrangement of 5-carbamylpyridazine-4-carboxylic acid ( 6 ), obtained from pyrida-zine-4,5-dicarboxylic acid ( 3 ) through the corresponding anhydride ( 5 ), afforded 5-aminopyrida-zine-4-carboxylic acid ( 1 ) in good yield. Compound 1 cyclised with benzoyl chloride in pyridine to give 2-phenylpyridazino[ 4 ,5-d]-1,3-oxazin-4-one ( 7 ), a new heterocyclic ring system. J. Heterocyclic Chem., 14, 1099 (1977)     

On pyrrolidine derivatives I. An efficient synthesis of 3-substituted (2S,5S)-pyrrolidine-2, 5-dicarboxylic acids

(2S,5S)-3-Alkylpyrrolidine-2, 5-dicarboxylic acid derivatives I were stereoselectively synthesized by means of an efficient method starting from L-aspartic acid ( 1 ). Dieckmann reaction of 4-benzyl 1-t-butyl N-t-butyl-oxycarbonyl-N-ethoxycarbonylmethyl-L-aspartate ( 4 ) provided product 5 which consisted of a mixture of (2S,5S)- and (2R,5S)-1-t-butyloxycarbonyl-3-oxopyrrolidine-2, 5-dicarboxylates in a ratio of 95:5. Treating 1-t-butyl 6-ethyl 2-L-(t-butyloxycarbonyl)anuno-5-diazo-4-oxoadipate ( 8 ), prepared from 1 , with rhodium(II) acetate dimer also afforded a good yield of 5 . The Wittig reaction of 5 , followed by catalytic hydrogenation and then deprotection provided compound I .     

Umlagerung von Allyl-aryläthern und Allyl-cyclohexadienonen mittels Bortrichlorid

Allyl aryl ethers which have no strongly electron attracting substituents undergo a charge-induced [3 s, 3 s] sigmatropic rearrangement in the prescence of 0.7 mole boron trichloride in chlorobenzene at low temperature, to give after hydrolysis the corresponding o-allyl phenols (Tables 1 and 2). The charge induction causes an increase in the reaction rate relative to the thermal Claisen rearrangement of ～10¹⁰. With the exception of allyl 3-methoxyphenyl ether (5) , m-substituted allyl aryl ethers show similar behaviour (with respect to the composition of the product mixture) to that observed in the thermal rearrangement (Table 3). The rearrangement of allyl aryl ethers with an alkyl group in the o-position, in the prescence of boron trichloride, yields a mixture of o- and p-allyl phenols, where more p-product is present than in the corresponding product mixture from the thermal rearrangement (Table 4). This ‘para-effect’ is especially noticeable for o-alkylated α-methylallyl aryl ethers (Table 5 ). With boron trichloride, 2,6-dialkylated allyl aryl ethers give reaction products which arise, in each case, from a sequence of an ortho-Claisen rearrangement followed by a [1,2]-, [3,3]- or [3,4]-shift of the allyl moiety (Tables 6 and 7). Ally1 mesityl ether (80), with boron trichloride, gives pure 3-ally1 mesitol ( 95 ). From phenol, penta-ally1 phenol ( 101 ) can be obtained by a total of five O-allylations followed by three thermal and two boron trichloride-induced rearrangements. The sigmatropic rearrangements of the ethers studied, using D- and ¹⁴C-labelled compounds, are collected in scheme 2; only the reaction steps indicated by heavy arrows are of importance. With protic acids, there is a [3,3]-shift of the allyl group in 6-allyl-2,6-disubstituted cyclohexa-2,4-dien-l-ones, while with boron trichloride the [3,3]-reaction is also observed along with the much less important [1,2]- and [3,4]-transformations (Table 8). 4-Allyl-4-alkyl-cyclohexa-2,5-dien-1-ones give only [3,3]-rearrangements with boron trichloride (Table 9). As expected, the naphthalenone 112 , which is formed by allowing boron trichloridc to react for a short time with allyl (1-methyl-2-naphthyl) ether ( 111 ), undergoes only a [3,4] rearrangement (Scheme 3). Representations of how, in our opinion, the complex behaviour of allyl aryl ethers and allyl cyclohexadienones under the influence of boron trichloride, can be rationalized are collected together in Schemes 4 and 5. In the last part of the discussion section, the steric factors leading to the appearance of the ‘para-effect’, are dealt with (Scheme 6).     

Tetrazole compounds. 8. Synthesis of tetrazolylpyrimidines from tetrazolyl-substituted enamino ketones

Tetrazolyl-substituted enamino ketones 1 react with various amidines 2 to give 5-(1-phenyl-1H-tetrazol-5-yl)pyrimidines 3 . In the case of the chloroacetyl enamine 4 4-(N,N-dimethylaminomethyl)-substituted tetra-zolylpyrimidines 5 were obtained. Subsequent hydrolysis of the 4-trifluoromethyl derivatives 3b, 3d and 3g afforded the corresponding 5-(1-phenyl-1H-tetrazol-5-yl)pyrimidine-4-carboxylic acids 6 .     

Stereoselective Synthesis of Polyfunctionalized Nitrothianes: Enhancement of Stereoselectivity by Microwaves

The Michael addition of nitromethane to (Z,Z)-2,2′-thiobis(1,3-diarylprop-2-en-1-ones) in the presence of NaOEt in dimethylformamide (DMF)/alcohol under thermal conditions affords a diastereomeric mixture of 2a,6e-diaroyl-3a,5e-diaryl-4e-nitrothianes and 2e,6e-diaroyl-3e,5e-diaryl-4e-nitrothianes with a dr of ～3:1/4:1 respectively. This reaction under microwave irradiation in DMF/alcohol afforded solely 2a,6e-diaroyl-3a,5e-diaryl-4e-nitrothianes, disclosing enhancement of stereoselectivity by microwaves.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.     

Hexitol derivatives containing a 1,4-oxathiane ring—III : Rearrangement of a sulfone on treatment with LAH

Treatment of 2,5 - anhydro - 3,4 - di -O- mesyl - 1,6 - thioanhydro - D - glucitol S,S-dioxide (1) with LAH afforded (1S,6R)-2-thiabicyclo[4.1.0]heptane S,S-dioxide (2) and its (4R) - 4 -hydroxy derivative 3 in a ratio of 46:6. Sodium - dihydro - bis(2 - methoxy - ethoxy) - aluminate afforded the same compounds in a ratio of 15:22. The corresponding sulfide 5 underwent no rearrangement under similar conditions. The structure of the products was established by IR, PMR, CMR and MS. A probable reaction mechanism is discussed.     

Synthesis of isonipecotinoyl analogues of aminopterin and folic acid

The preparation of isonipecotinoyl analogues of aminopterin and methotrexate is described. Condensation of diethyl N-isonipecotinoyl-L-glutamate 4 with 2-amino-5-bromomethyl-3-cyanopyrazine 5 afforded diethyl N-(N-[(2-amino-3-cyanopyrazin-5-yl)methyl]isonipecotinoyl)-L-glutamate 6 . Cyclisation of 6 with guanidine followed by blocking group hydrolysis afforded N-([N-(2,4-diaminopteridin-6-yl)methyl]isonipecotinoyl)-L-glutamic acid 8 . Coupling of N-(2-amino-4(3H)ioxopteridin-6-yl]methyl)isonipecotinic acid 11 with diethyl L-glutamate gave diethyl N-[(N-[2-amino-4(3H)-oxopteridin-6-yl]methyl)isonipecotinoyl]-L-glutamate 12 . Blocking group hydrolysis afforded N-[(N-[2-amino-4(3H)-oxopteridin-6-yl]methyl)isonipecotinoyl]-L-glutamic acid 13 .     

3-Oxo-1,2-benzoisothiazoline-2-acetic acid 1,1-dioxide derivatives. I. Reaction of esters with alkoxides

Reaction of 3-oxo-1,2-benzoisothiazoline-2-acetic acid alkyl esters 1,1-dioxide ( 1a-d ) with alkaline alkoxides was carried out under various conditions. Under mild conditions, o-(N-carboxymethylsulfamyl)benzoic acids dialkyl esters ( 2a-d ) were obtained with good yields. Reaction of 1a-d or 2a-d with sodium alkoxides under drastic conditions afforded 4-hydroxy-2H-1,2-benzothiazine-3-carboxylic acid alkyl esters 1,1-dioxide ( 3a-d ). Transesterification was observed when esters 1b-d were treated with sodium methoxide in methanol. Esters 3a-d were hydrolyzed in concentrated aqueous sodium hydroxide affording the acid 6 . Attempts to recrystallize 6 from water resulted in its decarboxylation to give 2H-1,2-benzothiazine-4-(3H)one 1,1-dioxide (7). Compound 6 could not be obtained by acid hydrolysis of esters 3a-d or by rearrangement of 3-oxo-1,2-benzoisothiazoline-2-acetic acid 1,1-dioxide ( 8 ). Different experimental evidence supports the suggestion that rearrangement took place by ethanolysis of the carboxamide linkage affording the open sulfonamides (fast step) followed by a Dieckmann cyclization (slow step). It was demonstrated that transesterification took place in the open sulfonamides 2 .     

Nucleosides. 130. Synthesis of 2′-Deoxy-2′-substituted- and 5′-Deoxy-5′-substituted-ψ-uridine Derivatives. Crystalline and Molecular Structure of 2′-Chloro-2′-deoxy-1,3-dimethyl-ψ-uridine. Studies Directed Toward the Synthesis of 2′-Deoxy-2′-substituted-arabino-Nucleosides. 1

A method was developed to prepare 5′-deoxy-5′-substituted-ψ-uridine derivatives 4 from 3′,5′-O-(1, 1, 3, 3-tetraisopropyldisiloxanyl)-1,3-dimethyl-ψ-uridine 1 via a silyl rearrangement reaction. Nucleophilic displacement of the mesyloxy function of 2′-O-mesyl-1,3-dimethyl-ψ-uridine 7 afforded products with the 2′-substituent in the “down” ribo configuration 8 . X-Ray crystallographic analysis of the 2′-chloro derivative 8a firmly established the molecular structure of 8 and provided evidence for neighboring group participation of the 4-carbonyl function of 7 during the nucleophilic reactions. Treatment of 1,3-dimethyl-ψ-uridine 11 with α-acetoxyisobutyryl chloride afforded a mixture from which two 2′-chloro-2′-deoxy-C-nucleosides were obtained. The major product (33% yield) was identical with 8 . The minor product (7% yield) was consequently assigned the arabino nucleoside 14 . This is the first direct introduction of a 2′-substituent in the “up” configuration in a preformed pyrimidine nucleoside.     

[2,3] Sigmatropic Rearrangement of Ethyl 2-(Diethoxyphosphoryloxy) Allyl Sulfoxides and Selenoxides. Synthetic Applications

Abstract

We have previously described regio- and stereospecific synthesis of ally1 selenides I and ally1 sulfides 2 [1]. We now report on the application of 1 and 2 as attractive precursors of new, functionalized: allylic alcohols 3, α-hydroxy ketones 4 and I, 3-dienes 5. 1 and 2 are transformed by oxidation into corresponding ally1 selenoxide and sulfoxide, which display stereospecific [2,3] sigmatropic rearrangement providing after hydrolysis the allylic alcohols 3. Trans configuration of 3 was established by X-ray analysis. In some cases the rearrangement is accompanied by elimination giving the 1,3-dienes 5. Compounds 3 and 5 can be easily separated by column chromatography Dephosphorylation of 3 afforded the α-hydroxy ketones 4.     

Synthesis of some substituted pyridylsydnones

Synthesis of the I-oxide ( 2 ) of the photochromic N-(3-pyridyl) sydnone ( 1 ), of N-(5-bromo-3-pyridyl) sydnone ( 3 ), and the I-oxide ( 4 ) of 3 were undertaken in order to study the effect on photochromism exerted by substituents on the pyridine ring. Compounds 2 and 3 were prepared via the corresponding aminopyridines and N-pyridylglycines by the general procedure used earlier to prepare 1 . The required amines, 3-aminopyridine I-oxide and 3-amino-5-bromopyridine, were obtained by Hofmann rearrangement of the corresponding amides. An excellent preparation of 5-bromonicotinamide was developed involving bromination in thionyl chloride followed by reaction of the bromoacid chloride with ammonia in chloroform. Proof of structure for 2 and 3 was accomplished by acid hydrolysis to the corresponding hydrazines, which were isolated, respectively, as acetophenone 3-pyridylhydrazone I-oxide and as 5-bromo-3-pyridylhydrazine hydrochloride. These products were identical with samples prepared by reduction of the respective diazotized amines. Sydnone 4 eluded preparation by this general procedure. 3-Amino-5-bromopyridine I-oxide was prepared conveniently from 5-bromonicotinamide but attempts to prepare the corresponding glycine by catalytic hydrogenation of a mixture of the amine and butyl glyoxylate afforded, in acid solution, N-(3-pyridyl)glycine and, in neutral or alkaline solution, the I-oxide of N-(3-pyridyl)glycine. Both products resulted from the reductive cleavage of the bromine atom. Neither 2 nor 3 was photochromic.     

Ylides of heterocycles. VII.. I-, N-, P- and S-ylides of pyrimidones

The reaction of pyrimidone derivatives 1a-d with iodosobenzene prepared in situ from diacetoxyiodobenzene or dichloroiodobenzene afforded the iodonium-ylides 2a-d in good yields. Their thermal rearrangement produced 5-iodo-4-phenoxy-pyrimidin-6(1H)-ones 3a-c . Reductive deiodination of 3 gave the corresponding 4-phenoxypyrimidin-6(1H)-ones 4a-c . Acid catalized treatment of the iodonium-ylides 2a-d with nucleophiles such as pyridine, nicotinamide, isoquinoline, or triphenylphosphine produced the corresponding N- or P-ylides 7, 8, 9 , and 10 , respectively. The thiophanium-ylides 11a,c were obtained from the iodonium-ylides 2 without the use of a catalyst. The pyridinium-ylides 7 have been also prepared from the 5-halopyrimidones 5 or 6 which in turn could be obtained from the reactive iodonium-ylides 2 with hydrochloric or hydrobromic acid, respectively.