6-alkyl and 5,6-dialkyl-2-methoxy-4(3H)- pyrimidinones in the transformations of pyrimidines—2: Synthesis and conversion into alkyluracils and 2-alkoxy-4(3H)-pyrimidinones

The synthesis of 6-alkyl and 5,6-dialkyl-2-methoxy-4(3H)-pyrimidinones 3 is described. Their versatility to be transformed into 6-alkyl and 5,6-dialkyluracils 4(a-h), 6-alkyl and 5,6-dialkyl-3-methyluracils 7(a,e,f) and 6-alkyl and 5,6-dialkyl-2-alkoxy-4(3H)-pyrimidinones 5(a-i) is also shown.     

Retro-ene reactions in heterocyclic synthesis,III. A new route to 4,5-dihydrooxazoles and 5,6-dihydro-4H-1,3-oxazines

Methyl (E)-4,4-dimethyl-5-oxo-2-pentenoate ( 1 , X = O) reacted with 1,2- or 1,3-aminoalcohols 3 to yield oxazolidines 4a-c or tetrahydro-1,3-oxazines 4d,e. The corresponding imino ester 1 (X = NBu-t) also gave 4 on reaction with 3 . Compounds 4 on heating at 230° yielded 4,5-dihydrooxazoles 5a-c or 5,6-dihydro-4H-1,3-oxazines 5d,e along with methyl 4-methyl-3-pentenoate ( 6 ).     

A new selective preparation of ethyl 7-aminopteridine-6- carboxylate derivatives and related compound

A series of ethyl 7-amino-2,4-dioxopteridine-6-carboxylates 4 and ethyl 7-amino-4-oxo-2-thioxopteridine-6-carboxylates 5 , of interest biologically, has been prepared in one step from the reaction of such vicinal-diamines as 1,3-dialkyl-5,6-diaminouracils 2 or 1,3-dialkyl-5,6-diamino-2-thiouracils 3 with diethyl (E)-2,3-dicyanobutenedioate ( 1 ). Moreover, ethyl 3-amino[1,2,4]triazino[2,3-a]-1H-benzimidazole-2-carboxylate ( 11 ) was also obtained from the reaction between 1,2-diamino-1H-benzimidazole ( 10 ) and 1 . The structural studies of 4, 5 , and 11 prepared were carried out by nmr experiments in some details.     

Synthesis of substituted 2-amino-5,6-dihydro-4h-1,3-oxazines and 2-iminotetrahydro-1,3-oxazines

3,4,4,6-Tetramethyl-2-aryliminotetrahydro-1,3-oxazines were synthesized by intramolecular cyclization of N-aryl-N′-methyl-N′-(2-methyl-4-hydroxy-2-pentyl)-S-methylisothioureas. 4,4,6-Trimethyl-2-(N-methyl-N-arylamino)-5,6-dihydro-4H-1,3-oxazines were obtained by methylation of 4,4,6-trimethyl-2-arylamino-5,6-dihydro-4H-1,3-oxazines.     

Cyclodimerization of 1-(Dimethoxyniethyl)-5,6-dimethylidene-7-oxa-bicyclo[2.2.1]hept-2-ene Induced by Nonacarbonyldiiron. Crystal Structure of (1RS, 2SR, 3RS, 4RS, 4aRS, 9aSR)- Tricarbonyl[C, 2,3, C-η-(1,4-epoxy-1,5-bis(dimethoxymethyl)-2,3-dimethylidene-1,2,3,4,4a,9,9a,10-octahydroanthracene)]iron

The transition-metal-carbonyl-induced cyclodimerization of 5,6-dimethylidene-7-oxabicyclo[2.2.1]hept-2-ene is strongly affected by substitution at C(1) While 5,6-dimethylidene-7-oxabicyclo[2.2.1]hept–2-ene-l-methanol ( 7 ) refused to undergo [4 + 2]-cyclodimerization in the presence of [Fe₂(CO)⁹] in MeOH, 1-(dimethoxymethyl)-5,6-di-methylidene-7-oxabicyclo[2.2.1]hept-2-ene ( 8 ) led to the formation of a 1.7:1 mixture of ‘trans’ ( 19, 21, 22 ) vs. ‘cis’ ( 20, 23, 24 ) products of cyclodimerization together with tricarbonyl[C, 5,6, C-η-(l-(dimethoxymethyl)-5,6-di-methylidenecyclohexa-1,3-diene)]iron ( 25 ) and tricarbonyl[C,3,4, C-η-(methyl 5-(dimethoxymethyl)-3,4-di-methylidenecyclohexa-1,5-diene-l-carboxylate)]iron ( 26 ). The structures of products 19 and of its exo ( 21 ) and endo ( 22 ) [Fe(CO)₃(1,3-diene)]complexes) and 20 (and of its exo ( 23 ) and endo (24) (Fe(CO)₃(1,3-diene)complexes) were confirmed by X-ray diffraction studies of crystalline (1RS, 2SR, 3RS, 4RS, 4aRS, 9aSR)-tricarbonyl[C, 2,3, C-η-(1,4-epoxy-1,5-bis(dimethoxymethyl])-2,3-dimethylidene-1,2,3,4,4a,9,9a,10-octahydroanthracene)iron ( 21 ). In the latter, the Fe(CO)₃(1,3-diene) moiety deviates significantly from the usual local C_s symmetry. Complex 21 corresponds to a ‘frozen equilibrium’ of rotamers with η-alkyl, η³-allyl bonding mode due to the acetal unit at the bridgehead centre C(1).     

Reaction of Ph3P(SCN)2 with Further Orthohydroxy Carboxylic Acid Systems,Including Substituted β-Keto Acids: Synthesis of Novel 2-Thio-1,3-oxazines and Their Subsequent Transformation with Amines

We now report the first reaction of Ph₃P(SCN)₂ with 4,6-dihydroxy-5-methylisophthalic acid to give 10-methyl-2,8-dithio-1,3-oxazino-1,3-benzoxazine-4,6-dione. Also, the enol tautomer has been utilized in the reaction of β-keto acids with Ph₃P(SCN)₂ to give novel 2-thio-1,3-oxazines. Subsequent reaction of the 2-thio-1,3-oxazines with benzylamine resulted in opening of the oxazine ring and gave novel dibenzylamino-enamides, which could be cyclized to thiouracils. The reaction of 2-thio-1,3-oxazines with morpholine at low temperature led to the production of unstable 2-Mercapto-2-morpholino-1,3-oxazines. 2-Mercapto-2-morpholin-4-yl-2,3,5,6,7,8-hexahydro-4H-1,3-benzoxazin-4-one was observed to lose H₂S at room temperature to give 2-morpholin-4-yl-5,6,7,8-tetrahydro-4H-1,3-benzoxazin-4-one, which was subsequently tested and found to exhibit some antiplatelet activity.     

Configurations and conformations of cis- and trans-N-methyl- and -N-benzyl-4,5- and -5,6-tetramethylenetetrahydro-1,3-oxazines

The configurations and conformations of cis- and trans-N-methyl- and -N-benzyl-4,5- and -5,6-tetramethylenetetrahydro-1,3-oxazines were determined by ¹H and ¹³C NMR spectroscopy. The cis isomers are conformationally homogeneous, having the hetero atom attached to the cyclohexyl ring, in the axial and equatorial positions, respectively, in the 5,6- and 4,5-tetramethylene compounds, similar to the case of the 2-p-nitrophenyl-substituted analogues investigated previously.     

Synthesis of ruthenium(II) N-heterocyclic carbene complexes and their catalytic activities in transfer hydrogenation of ketones

Three RuCl₂(η⁶-arene, η¹-carbene) and two RuCl₂(NHC)(arene) complexes have been prepared by the reaction of bis(1,3-dialkylperhydrobenzimidazol-2-ylidene) (1) and bis(1,3-dialkyl-4-methylzimidazolin-2-ylidene) (3) with [RuCl₂(arene)]₂ in toluene and characterized by elemental analysis, ¹H NMR, ¹³C NMR and IR spectroscopy. The catalytic activities of these complexes were examined in the transfer hydrogenation of aromatic ketones using 2-propanol as hydrogen source.     

Zur Kenntnis der Chemie und der Struktur von Olefin-monocyano-dicarbonyl-ferrat-Anionen

About Chemistry and Structure of Olefin-monocyano-dicarbonyl-ferrate Anions By the reactions of olenFe(CO)₃ [olen = C₅H₈(isoprene), C₇H₁₀(cycloheptadiene-1,3), C₈H₁₄(2,5-dimethylhexadiene-1,3)] with sodium bis [trimethylsilyl]amide the new anions [olenFe(CO)₂CN]^? are formed. All so far known [olenFe(CO)₂CN]^? complexes [olen = C₅H₈(isoprene), C₇H₁₀[cycloheptadiene-1,3], C₄H₆(butadiene), C₅H₈(pentadiene-1,3), C₆H₈(cyclohexadine-1,3), C₆H₁₀(2,3-dimethylbutadiene), C₈H₈(cyclooctatetraene)] have fluctional structures in solution as shown by ¹³C NMR spectroscopic investigations. At low temperatures only the isomer exists, in which the CN^? ligand and one of the two CO molecules occuppy the basal positions of a square pyramide together with 2 C atoms of the diene part.     

Tetranuclear cobalt trimethylacetate Co4(μ3-OH)2(μ-OOCBut)6(C4H6N2O)4 containing coordinated 3-methyl-5-pyrazolone

We found that the reaction of the compound obtained by alloying hydrous cobalt(II) acetate and pivalic acid with 3-methyl-5-pyrazolone in refluxing hexane produces the tetranuclear complex Co₄(μ₃-OH)₂(μ-OOCBu^t)₆·(C₄H₆N₂O)₄·2HOOCBu^t (complex 3). The complex has been structurally characterized using single-crystal X-ray diffraction     

Some Diels–Alder adducts of 6-vinyl-1-oxa-4-thiaspiro[4.5]dec-6-ene

6-Vinyl-1-oxa-4-thia­spiro­[4.5]­dec-6-ene has been reacted with dienophiles, such as N-phenyl­male­imide (NPM), N-methyl­triazoline-2,5-dione (MTAD) and di­methyl­acetyl­ene di­carboxyl­ate (DMAD), to assess the 1,3-diastereofacial selection caused by the acetal function. In each case, a mixture of two diastereoisomers was produced. The crystal structures of the products of the addition of NPM and MTAD syn to the acetal oxy­gen, 2-phenyl-2,3,3a,4,5,5a,6,7,8,9,9a,9b-dodeca­hydro-1H-benz­[e]­iso­indole-6-spiro-2′-[1′,3′]­oxa­thiol­ane-1,3-dione, C₂₀H₂₁NO₃S, (IIa), and 2-methyl-5,7,8,9,10,10a-hexa­hydro-1H-1,2,4-triazolo­[1,2-a]­cinnoline-7-spiro-2′-[1′,3′]­oxa­thiol­ane-1,3-dione, C₁₃H₁₇N₃O₃S, (IIIa), respectively, and the product of the addition of DMAD syn to the acetal sulfur, di­methyl 1,2,3,4,4a,7-hexa­hydro­naphthalene-1-spiro-2′-[1′,3′]­oxa­thiol­ane-5,6-di­carboxyl­ate, C₁₆H₂₀O₅S, (IVb), have been determined. All three structures are composed of independent mol­ecules separated by normal van der Waals distances. The 1-oxa-4-thia heterocyclic ring has an envelope conformation in the three structures and the S—Csp³ bond distances differ significantly from each other, as observed in comparable structures; the remaining molecular dimensions are as expected.     

Novel rhodium <Emphasis Type="Italic">N</Emphasis>-heterocyclic carbene catalysed arylation of aldehydes with phenylboronic acid

Reaction of 1,3-dialkylperhydrobenzimidazolinylidene, 1,3-dialkyl-4-methylimidazolinylidene and 1,3-dialkylimidazolinylidene with [RhCl(COD)]₂ yields {1,3-dialkylperhydrobenzimidazolin-2-ylidene}-, {1,3-dialkyl-4-methylimidazolin-2-ylidene}- {1,3-dialkylimidazolin-2-ylidene}chloro(η⁴-1,5-cyclooctadiene)rhodium(I) complexes (2a–c) and (4a, b). All compounds synthesised were characterised by elemental analysis, n.m.r. spectroscopy. Phenylboronic acid reacts with aldehydes in the presence of a catalytic amount of the new rhodium(I)–carbene complexes (2a–c) and (4a, b), to give the corresponding aryl secondary alcohols in good yield (73–99%).     

Zum verhalten konjugierter diene gegenüber C6H5J(OAc)2-(CH3)3SiN3

IR-spectroscopic measurements between ?60° and 0°C show the existence of C₆H₅J(OAc)_2-n(N₃)_n generated by the reaction of C₆H₅J(OAc)₂ with (CH₃)₃SiN₃. C₆H₅J(OAc)_2-n(N₃)_n reacts with 2,3-dimethylbutad to give substances C₁₂H₂₀N₆ (1), having the probable structure of 2,3,5-trimethyl-3,6-di-azidomethyl-heptadiene-1,5 and 3,4-diazido-3-methylbutanone-2 (2). Likewise we get from 1,3-cyclohexadiene the diazide C₁₂H₁₆N₆ (3), and 4-azido-cyclohexene-2-on-1 (4). Analogously from cyclopentadiene we get the carbonylcompound 4-azido-cyclopentene-2-on-1 (5). E-5-azido-hexene-3-on (8) results from 2,4-E,Z-hexadiene. 1,3-cyclooctadiene gives as main product 6 (4-azido-cyclooctene-2-on-1) but also some 7 (8-azido-cyclooctene-2-on-1) emerging from an attack on positions 1 and 2.Δ^1,3, Δ^3,5 and Δ^4,6-cholestadiene yield in a regio- and stereo-specific manner the products 9 (1α-azidocholestene-2-on-4), 10 (6β-azidocholestene-4-on-3) and 11 (4β-azidocholestene-5-on-7). These last examples confirm our suggestions from the preponderance of the 1,4-functionalisation.     

Regioselective electroreduction of 6h-1,3-thiazines. Comparison with chemical reductions I - investigation of 2-phenyl-6H-1,3-thiazines

The electrochemical reduction of 2-phenyl-6H-1,3-thiazines carried out at a mercury cathode in acetate buffer + ethanol (1:1) has been studied : - In the case of compounds monoactivated at carbon 5 (R⁵ = CHO or COCH₃) either hydrodimers (resulting from coupling at C-2), 3,6-dihydro-2H-1,3-thiazines (reduction of the imine bond) or tetrahydrothiazines can be obtained. - Diactivated 6H-1,3- thiazines (R⁴ = CO₂Et, R⁵ = CHO or COCH₃) successively lead to 5,6-dihydro-4H-1,3-thiazines (reduction of the ethylenic bond) and tetrahydrothiazines. - The reduction of a 6H-1,3-thiazine bearing only one withdrawing group at carbon 4 gives rise to a ring opening. At the same time, the action of various chemical reducing agents has been examined : the reduction of the imine bond is performed using NaBH₃CN while NaBH₄ or LiAlH₄ leads to the reduction of the substituents on the heterocyole.     

Cobalt(II) complexes with aminopolycarboxylate 1,3-pdta-type ligands: synthesis and characterization of trans(O6)-[Mg(H2O)6][CoII(1,3-pddadp)]·H2O

Starting from Ba₂(1,3-pddadp)·8H₂O (1,3-pddadp=1,3-propanediamine-N,N′-diacetate-N,N′-di-3-propionate ion) and CoSO₄, a new hexadentate [Co^II(1,3-pddadp)]²⁻ complex has been prepared. The trans(O₆) geometry of this complex was confirmed by comparison of its i.r. and u.v.–vis. spectra with those of [Co^II(1,3-pdta)]²⁻ (1,3-pdta is the 1,3-propanediaminetetraacetate ion) and trans(O₆)-[Co^III(1,3-pddadp)]⁻ complexes of known X-ray crystal structure. Magnetic and electrolytic conductivity properties of these complexes have also been discussed.     

2,3‐Dihydro‐1,3‐benzothiazol‐2‐iminium monohydrogen sulfate and 2‐iminio‐2,3‐dihydro‐1,3‐benzothiazole‐6‐sulfonate: a combined structural and theoretical study

The 2‐aminobenzothiazole sulfonation intermediate 2,3‐dihydro‐1,3‐benzothiazol‐2‐iminium monohydrogen sulfate, C₇H₇N₂S⁺·HSO₄⁻, (I), and the final product 2‐iminio‐2,3‐dihydro‐1,3‐benzothiazole‐6‐sulfonate, C₇H₆N₂O₃S₂, (II), both have the endocyclic N atom protonated; compound (I) exists as an ion pair and (II) forms a zwitterion. Intermolecular N—H...O and O—H...O hydrogen bonds are seen in both structures, with bonding energy (calculated on the basis of density functional theory) ranging from 1.06 to 14.15 kcal mol⁻¹. Hydrogen bonding in (I) and (II) creates DDDD and C(8)C(9)C(9) first‐level graph sets, respectively. Face‐to‐face stacking interactions are observed in both (I) and (II), but they are extremely weak.     

Propane‐1,3‐diaminium tetrachloridozincate(II) 18‐crown‐6 clathrate

The reaction of propane‐1,3‐diamine hydrochloride, 18‐crown‐6 and zinc(II) chloride in methanol solution yields the title complex salt [systematic name: propane‐1,3‐diaminium tetrachloridozincate(II)–1,4,7,10,13,16‐hexaoxacyclooctadecane (1/1)], (C₃H₁₂N₂)[ZnCl₄]·C₁₂H₂₄O₆, with an unusual supramolecular structure. The diprotonated propane‐1,3‐diaminium cation forms an unexpected 1:1 supramolecular rotator–stator complex with the crown ether, viz. [C₃H₁₂N₂(18‐crown‐6)]²⁺, in which one of the –NH₃⁺ substituents nests in the crown and interacts through N—H...O hydrogen bonding. The other –NH₃⁺ group interacts with the [ZnCl₄]²⁻ anion via N—H...Cl hydrogen bonding, forming cation–crown–anion ribbons parallel to [010].     

Fragmentation of selected C6H10O isomers: Evidence for a common [C5H7O]+ ion generated by methyl loss from cyclohexene oxide and 5,6-dihydro-4-methyl-2H-pyran

The loss of CH₃˙ from the molecular ions of cyclohexene oxide and 5,6-dihydro-4-methyl-2H-pyran has been investigated. On the basis of metastable peak shape analysis, collision-induced dissociation/mass-analysed ion kinetic energy spectra and thermochemical data it is concluded that the same [C₅H₇O]⁺ ion is formed in both cases.     

CHEMISTRY OF 1,3-OXAZINE-6-THIONES. RING TRANSFORMATION

Abstract

Two 1,3-oxazine-6-thione derivatives obtained by “S,N-Double Rearrangement²” reacted with several nucleophiles to produce 1,3-diazin-6-ones, 6-imino-1,3-oxazines, 1,3,4-triazoles, 1,2,4-oxadiazoles, and 1,3-thiazol-6-ones. Their ring transformations are discussed.     

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.