Stereoselective synthesis and Lewis acid mediated functionalization of novel 3-methylthio-β-lactams

A proficient etiquette for the stereoselective synthesis of novel 3-methylthio-β-lactams and their Lewis acid mediated functionalization is described. Treatment of 2-methylthioethanoic acid and appropriate imines in the Staudinger reaction leads to the stereocontrolled synthesis of novel trans-3-methylthio-β-lactams in excellent yields. cis-3-Chloro-3-methylthio-β-lactams, obtained from stereoselective chlorination of trans-3-methylthio-β-lactams using N-chlorosuccinimide (NCS) and AIBN, were subjected to Lewis acid (TiCl₄ or SnCl₄) mediated functionalization using various active aromatic, heterocyclic and aliphatic compounds (nucleophiles). This reaction provides an easy access to novel, stereoselective cis-3-monosubstituted-3-methylthio-β-lactams, which further undergo smooth desulfurization with Raney-nickel to afford C-3 cis- and trans-monosubstituted-β-lactams. The cis or trans configuration of the hydrogen/chloro/nucleophile substituent at C-3 was assigned with respect to C4–H.     

EC(EE) processes in the reduction of some 2-methylthio-4,6-di(alkylamino)-1,3,5-triazines on mercury electrodes

Polarographic (direct current, dc, and differential pulse, DP) studies of the electroreduction of the s-triazine derivatives ametryn (2-methylthio-4-ethylamino-6-isopropylamino)-1,3,5-triazine), dimethametryn (2-methylthio-4-ethylamino-6-(1,2-dimethylpropyl) amino-1,3,5-triazine) and simetryn (2-methylthio-4,6-di(ethylamino)-1,3,5-triazine) were made in the acidity range from 2.25 M H₂SO₄ to pH 6.5. Above this last pH value no signals were obtained. In DP polarography, two main reduction peaks were observed, accompanied by a pre-peak due to the adsorption of the herbicides on the electrode. The main peaks corresponded to two-electron irreversible reduction processes, at pH values higher than the protonation pK of the triazine ring (ca. 4). In this pH range, the protonation of the triazine ring preceding the reduction process is responsible for decrease in limiting current. At pH<pK the herbicides suffer a cleavage of the –SCH₃ group via two different intermediates related by a chemical reaction, whose extension depends on the herbicide.     

Synthesis of the functionally 4-substituted 1-methyl-3-thioxo-2,3,5,6,7,8-hexahydroisoquinolines by S<Subscript>N</Subscript>Vin reaction of 2-acetyl-1-(<Emphasis Type="Italic">N</Emphasis>-morpholinyl)cyclohexene with malonothio(dithio)amides

4-Carbamoyl(thiocarbamoyl)-3-thioxo-2,3,5,6,7,8-hexahydroisoquinolines were synthesized by the S_NVin reaction of 2-acetyl-1-(N-morpholinyl)acetylcyclohexene with malonothio(dithio)amides. The cyclocondensation direction was confirmed with the X-ray diffraction analysis of 1-methyl-3-methylthio-5,6,7,8-tetrahydroisoquinoline-4-carboxamide.     

Stereospecific synthesis of some polycyclic cis-β-lactams

Amides 1 on reaction with P₂S₅ in pyridine give thioamides 2 which on treatment with methyl iodide afford the corresponding 1-methylthio-3,4-dihydroisoquinolines 3. Annelation of these imines with phenoxyacetyl chloride in the presence of triethylamine furnish 6-methylthio-7-phenoxy-2',3' - dimethoxybenzo[a]octem 4a and 6-methylthio-7-phenoxy-2,3-methylenedioxybenzo[a]octem 4b respectively. Desulphurisation of these β-methylthio-β-lactams with Raney nickel yield the novel polycyclic cis-β-lactams 5a and 5b.     

One-Pot synthesis of N-heterocyclic compounds from cyclopropenethione derivatives

The one-pot reaction of 2-tert-butylthio-3-phenylcyclopropenethione (1a) and its 3-(2-thienyl) derivative (1b) with lithium pyrrolidinide at -70 degrees C, followed by methylation with methyl iodide, gives 6-methylthio-5-phenyl-2,3-dihydro-1H-pyrrolizine (2a) and its 5-(2-thienyl) derivative (2b), respectively. The reaction of 2-tert-butylthio-3-(pyrrolidin-1-yl)cyclopropenethione (1c) with phenyllithium gives also 2a in a high yield under similar conditions, and the reactions of 1a with N-lithium salts of 3-pyrroline, hexamethyleneimine, indoline, and carbazole, piperidine-potassium tert-butoxide mixture, and phenyllithium give 6-methylthio-5-phenyl-3H-pyrrolizine (3), 2-methylthio-3-phenyl-6,7, 8,9-tetrahydro-5H-pyrrolo[1,2-a]azepine (5), 6-tert-butylthio-5-methylthio-4-phenyl-1,2-dihydro-6H-pyrrolo[3,2, 1-ij]quinoline (6), 4-tert-butylthio-5-methylthio-6-phenyl-4H-pyrido[3,2,1-jk]carbazole (7), 2-methylthio-3-phenyl-5,6,7,8-tetrahydroindolizine (4), and 1-tert-butylthio-2-methylthio-3-phenylindene (9), respectively. The structures of 2a and 3 were determined by X-ray analyses of their tricarbonylchromium complexes.     

Palladium-catalyzed reaction of methyl 5-amino-4-chloro-2-methylthiopyrrolo[2,3-<Emphasis Type="Italic">d</Emphasis>]-pyrimidine-6-carboxylate with arylboronic acids. Synthesis of 1,3,4,6-tetraazadibenzo[<Emphasis Type="Italic">cd,f</Emphasis>]-azulene heterocyclic system

Densely substituted methyl 5-amino-4-aryl-7-methyl-2-methylthio-7H-pyrrolo[2,3-d]pyrimidine-6-carboxy- lates were synthesized by the palladium-catalyzed cross-coupling reaction of methyl 5-amino-4-chloro-7-methyl-2-methylthio-7H-pyrrolo[2,3-d]pyrimidine-6-carboxylate with arylboronic acids using Pd(OAc)₂/dicyclohexyl(2-biphenyl)phosphine/K₃PO₄ as a catalyst system. Reaction of methyl 5-amino-4-chloro-7-methyl-2-methylthio-7H-pyrrolo[2,3-d]pyrimidine-6-carboxylate with 2-formylphenyl- boronic acid led to a novel heterocyclic system – 1,3,4,6-tetraazadibenzo[cd,f]azulene.     

Synthesis of trifluoromethyl-substituted salicylates by cyclocondensation of 1,3-bis(silyloxy)-1,3-butadienes with 4,4-dimethylthio-1,1,1-trifluorobut-3-en-2-one

A formal [3+3] cyclocondensation of 1,3-bis(silyl enol ethers) with the little-known 4,4-dimethylthio-1,1,1-trifluorobut-3-en-2-one was studied. In contrast to 4,4-dimethoxy-1,1,1-trifluorobut-3-en-2-one, this α-oxoketene dithioacetal reacts with 1,3-bis(trimethylsilyloxy)-1,3-butadienes in the presence of TiCl₄ to give mainly 6-methylthio-4-(trifluoromethyl)salicylates via 1,2-addition. The scope and limitations of the reaction are discussed.     

Pyridinethiones. XV. 3-Methylthio-2-pentene-1,5-diones as synthons for 4-methylthio-2(1H)-pyridinethiones,and synthesis of 4-methylene-1,4-dihydropyridines

Starting from α-oxoketene dithioacetals the 3-methyithio-1,5-pentenedione enolates 4 obtained from ketones 3 give 4-methylthio-2(1H)-pyridinethiones with isothiocyanates. Enolates 4 can be alkylated with methyl iodide at C-2, giving 5-methyl-4-methylthio-2-(1H)-pyridmethiones with isothiocyanates. The S-alkylated pyridinethiones react with the anion of malodinitrile, giving 4-(1,1-dicyanomethylene)-1,4-dihydropyridines.     

Synthesis and thermal decomposition of haloalkoxy-sym-triazines

Reaction of [2-methylthio-6-dialkylamino-sym-triazin-4-yl]trimethylammonium chlorides with ethylene chlorohydrin gave 2-methylthio-4-(2-chloroethoxy)-6-dialkylamino-sym-triazines, which are converted to 2-methylthio-3-(2-chloroethyl)-4-oxo-6-dialkylamino-3,4-dihydro-symtriazines when they are heated to 115–120°C and to the corresponding tetrahydrothiazolo-symtriazine derivatives when they are heated at 180–190°C.See [1] for communication II.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1420–1423, October, 1977.     

Alkylation of 4-hydroxy-6-methyl-2-methylthio-pyrimidine with chloroacetonitrile

The sodium salt of 4-hydroxy-6-methyl-2-methylthiopyrimidine is alkylated with chloroacetonitrile in hexamethyltriamidophosphate on the O-atom, and in dioxane or tetrahydrofuran on the N₃-atom, with the formation of 6-methyl-2-methylthio-4-cyanomethoxypyrimidine and 6-methyl-2-methylthio-3-cyanomethyl-4-pyrimidone, respectively.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1525–1527, November, 1992.     

1H NMR study of cis-trans isomerization in two analogs of the thiol form of thiamine

Proton magnetic resonance (¹H NMR) was used to study cis-trans isomerization in N-methyl-N-(1-methylthio-2-propenyl)formamide and N-benzyl-N-(1-methylthio-2-propenyl)formamide, two analogs of the thiol form of thiamine. Benzene dilution studies and shift reagent studies were used to make resonance assignments, which indicate that the predominant isomer for each analog has the C? C bond trans to the carbonyl oxygen. Shift reagent studies, using Pr(fod)₃ in CCl₄ or CDCl₃, suggest that the reagent may be bonding to both the nitrogen and oxygen atoms of the substrate. For some of the systems studied, varying ρ at constant temperature had the same spectral effect as varying temperature at constant ρ.     

METHYLTHIODITHIOLYLIUM REACTIONS WITH 2-BUTENE NITRILES DERIVATIVES

Abstract

The 3-methylthio-1. 2-dithiolylium including at 5 position a donor substituent, in acetic acid in the presence of pyridine, the 2-methylthio-1. 3-dithiolylium ions in methylene chloride-triethylamine, react with the 2-butene nitrile derivatives and lead to the (A) and (B) corresponding 4-dithiolylidene-2-butene nitriles. In contrast ring opening reaction of the 1, 2-dithiole is observed when 2-cyano-3-phenyl-2-butene nitrile reacts with the 3-methylthio-4-aryl-1. 2-dithiolylium ions in 3 and 5 positions, in methylene chloride-triethylamine. The nucleophilic attack on the 5 position of the dithiolylium ion leads to a 2-cyano-3-phenyl-3 (4-aryl-5-methylthio-2-thienyl) propene nitrile (C), meanwhile the attack on the 3 position leads to a 2-cyano-3-phenyl-3-(4-aryl-3-mercapto-2-thienyl) propene nitrile (D). The proposed structures are established by means of physical methods (IR, NMR, and Mass Spectrometry) and by non ambiguous synthesis. The reactivities of the various sites are explained in function of the electronic and steric effects, furthermore the reaction conditions and the intermediary isolation allow to propose the mecanisms of these reactions.     

Synthesis of 8-amino-4-methylthio-6-methyl-2-(β-D-ribofuranosyl)-2,6-dihydro-1,2,3,5,6,7-hexaazaacenaphthylene and an unusual reductive ring-opening of the 1,2,3,5,6,7-hexaazaacenaphthylene ring system

The tricyclic nucleoside 8-amino-4-methylthio-6-methyl-2-(β-D-ribofuranosyl)-1,2,3,5,6,7-hexaazaacenaphthylene ( 3 ) was synthesized from 3-cyano-4,6-bis(methylthio)-1-(β-D-ribofuranosyl)pyrazolo[3,4-d]pyrimidine ( 1 ). Attempts to synthesize 8-amino-6-methyl-2-(β-D-ribofuranosyl)-1H-2,6-dihydro-1,2,3,5,6,7-hexaazaacenaphthylene ( 5 ) ([an aza analog of 6-amino-4-methyl-8-(β-D-ribofuranosyl)-1,3,4,5,8-pentaazaacenaphthylene (TCN)], which is a potent antitumor agent), by the treatment of 3 with Raney nickel did not afford the desired aza analog of TCN. Instead, it was established that a reductive cleavage of the pyridazine moiety of 3 had occurred to give 4-methylamino-6-methylthio-1-(β-D-ribofuranosyl)-1H-pyrazolo[3,4-d]pyrimidine-3-carboxamidine ( 6 ). Assuming that solubility was a problem in the reductive step, the isopropylidene derivative of 3 , 8-amino-6-methyl-4-methylthio-2-(2,3-O-isopropylidene-β-D-ribofuranosyl)-2,6-dihydro-1,2,3,5,6,7-hexaazaacenaphthylene ( 8 ), was treated with Raney nickel, only to observe that a similar reductive ring cleavage of 8 had occurred to afford 4-methylamino-6-methylthio-1-(2,3-O-isopropylidene-β-D-ribofuranosyl)-1H-pyrazolo[3,4-d]pyrimidine-3-carboxamidine ( 10 ) and 4-methylamino-1-(2,3-O-isopropylidene-β-D-ribofuranosyl)-1H-pyrazolo[3,4-d]pyrimidine-3-carboxamidine ( 11 ). Structural assignments for all products were established by physico-chemical procedures.     

Crystal solvates and polymorphs of N-(3-methylthio-1,2,4-thiadiazol-5-yl-aminocarbonylmethyl)cytisine

A polymorphs, crystallohydrate and crystallosolvates of N-(3-methylthio-1,2,4-thiadiazol-5-yl-aminocarbonylmethyl)cytisine, C₁₆H₁₉N₅O₂S₂, with chloroform, methanol, benzene have been obtained and crystal structures have been determined by the method of single crystal X-ray diffraction. In the investigated crystals N-(3-methylthio-1,2,4-thiadiazol-5-yl-aminocarbonylmethyl)cytisine have taken four types of conformation due to intra-molecular rotations around N–C and C–C bonds. So free rotations in the molecule assisted in formation a different crystallosolvates and polymorphs depending on nature of solvents. The thermal decomposition of the hydrate and methanol solvated crystals was studied by means of a TG-DSC.     

Über die Umlagerung von Benzo[b]-1, 4-thiazepinen und 1, 4-Thiazepinen

The rearrangement of differently substituted 1, 4-thiazepines under various reaction conditions has been investigated. 2-Phenyl-4-methylthio-benzo [b]-1, 4-thiazepine ( 3 ) and 2-phenyl-benzo [b]-1, 4-thiazepine-4 (5H)-thione ( 2 ) extrude sulfur under the catalytic influence of bases and rearrange into 2-methylthio-4-phenyl-quinoline ( 4 ) and 4-phenyl-thiocarbostyril ( 6 ) respectively. Under the same conditions, 2-phenyl-4-methylthio-2, 3-dihydro-benzo [b]-1, 4-thiazepine ( 11 ) rearranges to 2-styryl-benzothiazine ( 12 ), whereas the dioxide 18 shows no tendency to rearrange. 2,7-Diphenyl-hexahydro-1,4-thiazepine-5-one( 19 ) could be converted into 2-styryl-5-phenyl-2-thiazoline ( 20 ) by treatment with polyphosphoric acid. The possible mechanisms of these rearrangements are discussed.     

Synthesis of 4-methylthio-2(1H)-pyridone derivatives using ketene dithioacetals

Reaction of various active methylene compounds with ketene dithioacetals, bis(methylthio)methylenemalononitrile (1a) and bis(methylthio)methylenecyanoacetamide (1b) gave the corresponding 3-cyano-4-methylthio-2(1H)-pyridone derivatives. The transformation of 4-methylthio-2-oxo-2H-pyran-3-carbonitrile in-to 4-methylthio-2(1H)-pyridone derivatives was also described.     

A galactoside derivative of a nitrosoisocytosine inhibitor of dihydropteroate synthase: Synthesis and biological evaluation

The synthesis of the O-β-D-galactosyl derivative 3 of the dihydropteroate synthase inhibitor 6-(3-(4-hydroxyphenoxy)propylamino)-5-nitrosoisocytosine ( 2 ) was accomplished through coupling of N-(3-(4-hydroxyphenoxy)propyl)phthalimide ( 4 ) with 2,3,4,6-tetra-O-acetyl-α-D-galactopyranosyl bromide followed by complete deblocking of the resulting β-glycoside 9 with hydrazine and then methanolic ammonia to provide amine 10 , and subsequent condensation of 10 with 6-methylthio-5-nitrosoisocytosine ( 11 ). Glycoside 3 inhibited the synthase with moderate potency (I₅₀ = 11 μM) but did not exhibit antibacterial activity.     

Synthesis of 2-acyl-3-methylthiofurans from 3-methylthio-2-pentene-1,5-dione enolates

2-Acyl-3-methylthiofurans 3 are obtained in fair yields from 3-methylthio-2-pentene-1,5-dione enolates 1 by reaction with iodine. In a similar reaction 1-phenyl-3-methylthio-4-nitro-2-buten-1-one gave 3-methylthio-2-nitro-5-phenylfuran 11. In the crystalline state the 2-benzoyl-3-methylthio-5-phenylfuran 3b showed a non-bonded sulfur-oxygen interaction as inferred from an X-ray diffraction determination, with a S····O distance of 2.871(5)Å.     

REACTIONS OF HYDRAZONOYL HALIDES 371: SYNTHESIS OF TRIAZOLO[4,3-a]PYRIMIDINES, 1,3,4-THIADIAZOLES AND 1,3,4-SELENADIAZOLES

1,2,4-Triazolo[4,3-a]pyrimidines, thiadiazolines and selenadiazolines synthesized via reactions of hydrazonoyl halides with each of ethyl 4-(3,4-dimethoxyphenyl)-6-methyl-2-methylthio-3,4-dihydropyrimidine-5-carboxylate (or ethyl 6-(3,4-dimethylphenyl)-4-methyl-2-thio1,3,6-trihydropyrimidine-5-carboxylate), ethyl 4-(2,3-dimethoxyphenyl)- 6-methyl-2-methylthio-3,4-dihydropyrimidine-5-carboxylate, potassium thiocyanate, potassium selenocyanate, and carbodithioates respectively.     

Synthesis of 1,4,6,7-tetrahydroimidazo[2,1-c] [1,2,4] triazines

From 2-methylthioimidazoline and phenaeylbromides in DMF there were obtained the 2-(2-methylthio-2-imidazolin-1-yl)aeetopht'nones 3a-3f . From these the substituted 3-phenyl-1,4,6,7-tetrahytlroimidazo[2,1-c][1,2,4]triazines 4a-4n were prepared upon reaction with hydrazine and methylhydrazine respectively. Compound 4a was degraded to the triazine 6. From the (2-methylthio-2-imidazolin-l-yl)-acetie acid ester 10, the imidazo[2,1-c] [1,2,4]triazines 11a-11c were prepared. Selective ethylation on the oxygen was achieved with 11b in the presence of Meerwein' salt.