取代金刚烷的异构体计数

采用图论方法对单一种取代基取代的金刚烷和烷基取代的金刚烷构型、手性构型和非手性构型数进行了计算,结果分别以母函数形式和表格形式给出。     

The first selective one-pot synthesis of 1,3-dicarbonyl adamantanes from adamantane and 1,3-dimethyladamantane

A new approach to a simple one-pot functionalization of adamantane and 1,3-dimethyladamantane with CO and various nucleophiles in the presence of the superelectrophilic complex, CBr₄·2AlBr₃ provides access to important 1,3-dicarbonyl adamantanes with two new functional groups at the bridge-head positions.     

Regioselective synthesis of the 3,4-dihydrofuro[3,2-d]pyrimidin-2(1H)-one skeleton: a new class of compound

We hereby report the first preparation of the 3,4-dihydrofuro[3,2-d]pyrimidin-2(1H)-one skeleton formed by two controlled Curtius rearrangements of the corresponding acyl azides, prepared from 2-(2-methoxy-2-oxoethyl)furan-3-carboxylate via the hydrazide. Rearrangement of the acyl azides followed by trapping by nucleophiles and intramolecular trapping provided the target compounds.     

A novel class of compounds: synthesis of 5,5′-carbonyl-bis(5,6-dihydro-4H-furo- and thieno-[2,3-c]pyrrol-4-ones)

We hereby report the first synthesis of novel class of compounds, 5,5′-carbonyl-bis(5,6-dihydro-4H-thieno- and furo-[2,3-c]pyrrol-4-one starting from methyl 2-(2-methoxy-2-oxoethyl) thiophene- and furan-3-carboxylate, respectively. The ester functionalities connected to methylene group were regiospecifically converted to the desired monoacyl azides. Curtius rearrangement of acyl azides followed by hydrolysis of the formed isocyanates gave the symmetrical urea derivatives. Cyclization of the ester groups provided the target compounds.     

Simple and regioselective bromination of 5,6-disubstituted-indan-1-ones with Br2 under acidic and basic conditions

Bromination of 5,6-dimethoxyindan-1-one with Br(2) in acetic acid at room temperature produced exclusively the corresponding 2,4-dibromo compound in 95% yield. Reaction of 5,6-dimethoxyindan-1-one with Br(2) in the presence of KOH, K(2)CO(3) or Cs(2)CO(3 )at ~0 degrees C( )gave the monobrominated product 4-bromo-5,6-dimethoxyindan-3-one in 79%, 81% and 67% yield, respectively. 5,6-Dihydroxyindan-1-one was dibrominated on the aromatic ring affording 4,7-dibromo-5,6-dihydroxyindan-1-one both in acetic acid at room temperature and in the presence of KOH at ~0 degrees C. 5,6-Difluoroindan-1-one and 1-indanone were alpha-monobrominated in acetic acid and alpha,alpha-dibrominated under KOH conditions at room temperature.     

Derivatives of condensed pyrimidine,pyrazine, and pyridine systems

Reaction of 2-mercapto-3-amino-5,6-dimethyl- and 2-mercapto-3-amino-5,6-diphenylpyrazines withα-halo acid esters gave 2-carbethoxy-3-aminopyrazines, which are converted by the action of sodium ethoxide to 5,6-dimethyl- and 5,6-diphenylpyrazino[2,3-b]-[1,4]thiazin-6-ones. The latter are more conveniently obtained from 2-chloro-3-amino-5,6-dimethyl- and 2-chloro-3-amino-5,6-diphenylpyrazines and thioglycolic acid. 5,6-Dihydropyrazinothiazine is formed by reduction of 5,6-dimethyl pyrazino[2,3-b][1,4]thiazin-6-one, whereas the 2,3-dimethyl-5-amino-6-sulfonic acid and its N-oxide are formed by oxidation.     

Theoretical study of the role of solvent H2O in neopentyl and pinacol rearrangements

The neopentyl and the pinacol rearrangements as examples of Wagner-Meerwein rearrangements were investigated by the use of DFT calculations. As the first reaction, a model of neopentyl chloride (1b) and (H2O)12 was employed. In the reaction, the patterns of C--Cl scission, methyl migration, and C--OH formation were analyzed. The calculations have shown that the 2-methyl-2-butanol (6) is formed in two steps with the transient intermediate, neopentyl alcohol (3). The first step is the nucleophilic substitution reaction and is the rate-determining one. The second step is the dual migration of methyl and OH2 groups. The primary and tertiary carbocations were calculated to be absent in the neopentyl rearrangement starting from the hydrolysis. As the second reaction, the pinacol rearrangement of two substrates 2,3-dimethyl-2,3-butanediol (7) and 2,3-diphenyl-2,3-butanediol (12) was investigated. Acidic aqueous solvent was modeled by H3O+ and 12H2O. The reaction paths were promoted by a hydrogen-bond circuit of H3O+(H2O)2 and were determined as completely concerted processes. Protonated species and carbocations as intermediates also do not intervene during the pinacol rearrangement. Active functions of proton relays along the hydrogen bonds in the two rearrangements were demonstrated.     

Palladium catalyzed C-C coupling reactions of 3,5-dichloro-4H-1,2,6-thiadiazin-4-one

Palladium catalyzed Suzuki-Miyaura, Stille, and Sonogashira coupling reactions are reported for the electron-deficient heterocyclic scaffold 3,5-dichloro-4H-1,2,6-thiadiazin-4-one (1). Furthermore, 3,5-di(thien-2-yl)-4H-1,2,6-thiadiazin-4-one (7m) is further elaborated to afford the tetrathienyl 3,5-bis[(2,2'-bithien)-5-yl]-4H-1,2,6-thiadiazin-4-one (9). All compounds are fully characterized.     

Behaviour of 5,6-dihydrothieno[2,3-h]cinnolin-3(2H)-one and 5,6-dihydrothieno[3,2-h]cinnolin-3(2H)-one towards hydrazine. Synthesis of thienocinnolinones and of 4-aminothienocinnolinones

The isomeric compounds 5,6-dihydrothieno[2,3-h]cinnolin-3(2H)-one ( 7a ) and 5,6-dihydrothieno-[3,2-h]cinnolin-3(2H)-one ( 7b ) rapidly tautomerise to the corresponding 1,4-dihydrothienocinnolinones 8a,b when kept in refluxing hydrazine hydrate. With longer reaction times the initially formed 8a,b dehydrogenate to the thienocinnolinones 9a,b which eventually are aminated to 4-aminothienocinnolinones 10a,b . This behaviour recalls that reported for the related 5,6-dihydrobenzocinnolin-3(2H)-one ( 1 ) which under the same conditions undergoes dehydrogenation to benzo[h]cinnolin-3(2H)-one ( 2 ) followed by 4-amination to 3 , but differs for the stability of the intermediates, for the mechanism of the final amination, and for the higher reaction rate. All these differences can be rationalised in terms of the heats of formation of the intermediates and products of the two series of transformations.     

2-Phenyl-4-quinolinone Alkaloids from Casimiroa edulis Llave et Lex (Rutaceae)

Summary.  Three new 4-quinolinone alkaloids (5,6-dimethoxy-2-(3-methoxyphenyl)-1H-quinolin-4-one, 5,6-dimethoxy-2-(3,4-dimethoxyphenyl)-1H-quinolin-4-one, 5,6-dimethoxy-2-(2,5,6-trimethoxyphenyl)-1H-quinolin-4-one) were isolated from the leaves of Casimiroa edulis Llave et Lex (Rutaceae) cultivated in Egypt. Their structures were determined by UV/Vis, IR, ¹H and ¹³C NMR, and EI mass spectroscopy. The alkaloids were also detected in the kernels of the seeds. Received May 28, 2001. Accepted (revised) July 24, 2001     

2-Phenyl-4-quinolinone Alkaloids from Casimiroa edulis Llave et Lex (Rutaceae)

 Three new 4-quinolinone alkaloids (5,6-dimethoxy-2-(3-methoxyphenyl)-1H-quinolin-4-one, 5,6-dimethoxy-2-(3,4-dimethoxyphenyl)-1H-quinolin-4-one, 5,6-dimethoxy-2-(2,5,6-trimethoxyphenyl)-1H-quinolin-4-one) were isolated from the leaves of Casimiroa edulis Llave et Lex (Rutaceae) cultivated in Egypt. Their structures were determined by UV/Vis, IR, ¹H and ¹³C NMR, and EI mass spectroscopy. The alkaloids were also detected in the kernels of the seeds.     

Polyketides from a marine sponge-derived fungus Mycelia sterilia and proton-proton long-range coupling

A series of polyketide-originated metabolites (1-5) were isolated from a marine sponge-derived fungus Mycelia sterilia. Of these, 1-3 were new compounds. Their structures were elucidated by spectroscopic methods as (4R*, 5S*, 6S*, 8S*, 13R*)-1-(2,8-dihydroxy-1,2,6-trimethyl-1,2,6,7,8,8a-hexahydro-naphthalen-1-yl)-3-methoxy-propan-1-one (1), 4,8-dihydroxy-7-(2-hydroxy-ethyl)-6-methoxy-3,4-dihydro-2H-naphthalen-1-one (2) and 1-methyl-naphthalene-2,6-dicarboxylic acid (3). In 1, the proton-proton long-range coupling phenomenon claimed attention and was discussed.     

Selective Stille coupling reactions of 3-chloro-5-halo(pseudohalo)-4H-1,2,6-thiadiazin-4-ones

A series of 3-chloro-5-halo(pseudohalo)-4H-1,2,6-thiadiazin-4-ones (halo/pseudohalo = Br, I, OTf) are prepared from 3,5-dichloro-4H-1,2,6-thiadiazin-4-one (3) in good yields. Of these the triflate reacts with tributyltin arenes (Stille couplings) chemoselectively to give only the 5-aryl-3-chloro-4H-1,2,6-thiadiazin-4-ones in high yields. This allowed the preparation of a series of unsymmetrical biaryl thiadiazines and ultimately a series of oligomers. Furthermore, treatment of 3-chloro-5-iodo-4H-1,2,6-thiadiazin-4-one (10) with Bu(3)SnH and Pd(OAc)(2) gave the bithiadiazinone which can also be further arylated via the Stille reaction to give bisthien-2-yl and bis(N-methylpyrrol-2-yl) analogs.     

Functionalized 5,6-dihydro-2H-1,2,6-thiadiazine 1,1-dioxides. Synthesis,structure and chemistry

Treatment of sulfamide 4a and aryl-substituted sulfamides 4b-e with ethyl 3,3-diethoxypropionate ( 13 ) provided a convenient procedure for the synthesis of functionalized 5,6-dihydro-2H-1,2,6-thiadiazine 1,1-dioxides 14 . Key spectral properties of this novel class of heterocycles are reported. The generality and utility of this transformation is briefly explored.     

Reactions of 4-pyrones with primary amines. A new class of ionic associates

Primary aliphatic amines react with 2,6-dimethyl-4-pyrone to give 2,6-dialkylamino-2,5-heptadien-4-one derivatives. When the alkyl group was methyl, the diamino derivative cyclized on warming to give 1,2,6-trimethyl-4-pyridone. The corresponding butylamino derivative did not thermally cyclize, but did give a pyridone on treatment with acid. The isopropylaminoketone did not cyclize. Several examples of 1,2,6-trisubstituted-4-pyridones formed “ionic associates” consisting of two parts of the pyridone and one part of perchloric acid. These associates are useful primary standards for nonaqueous titrations.     

Condensation of the isoindole–isoindoline isomers of the thieno[3′,2′:5,6]pyrimido[2,1-a]isoindol-6(10H)-one with aldehydes

The reaction of the isoindole–isoindoline isomers of the thieno[3′,2′:5,6]pyrimido[2,1-a]isoindol-6(10H)-one with aldehydes gives new benzylidene thieno[3′,2′:5,6]pyrimido[2,1-a]isoindol-6(10H)-one derivatives. The structures were assessed with NMR, UV spectroscopy and mass spectra.     

The synthesis of 2-chloro-1-β-D-ribofuranosyl-5,6-dimethylbenzimidazole and (certain related derivatives

The synthesis of 2-chloro-1-(β-D -ribofuranosyl)-5,6-dimethylbenzimidazole (3b) has been accomplished by a condensation of 1-trimethylsilyl-2-chloro-5,6-dimethylbenzimidazole (1) with 2,3,5-tri-O-acetyl-D -ribofuranosyl bromide (2) followed by subsequent deacetylation. Nucleophilic displacement of the 2-chloro group from 3b has furnished several interesting 2-substituted-1-(β-D -ribofuranosyl)-5,6-dimethylbenzimidazoles. 1-(β-D -Ribofuranosyl)-5,6-dimethylbenzimidazole (5) and 1-(β-D -ribofuranosyl)-5,6-dimethylbenzimidazole-2-thione (4) were prepared from 3b. Alkylation of 4 furnished certain 2-alkylthio-1-(β-D -ribofuranosyl)-5,6-dirnethylbenzimidazoles and oxidation of 4 with alkaline hydrogen peroxide produced 1-(β-D -ribofuranosyl)-5,6-dimethylbenzimidazole-2-one D The assignment of anomeric configuration for all nucleosides reported is discussed.     

Photocycloaddition of Benzothiazole-2-thiones to Alkenes

The photocycloaddition of benzothiazole-2-thiones to electron-rich and aryl-substituted alkenes are described. Irradiation of N-unsubstituted benzothiazole-2-thione ( 1 ) in the presence of alkenes 3 gave 2-(2′-mercaptoalkyl)benzothiazoles 4 , and 2-substituted benzothiazoles 5 and 6 (in the case of 3a and 3h , resp.) through the ring cleavage of an intermediate 2-aminothietane (Schemes 1 and 3 ). The latter was formed by [2+2] cycloaddition of the C?S bond of 1 and the C?C bond of 3 . Irradiation of N-methylbenzothiazole-2-thione ( 2 ) and 2-methylpropene ( 3a ) gave the spiro-1,3-dithiane 8 , 1,2,6-benzodithiazocin-5-one 9 , and disulfide 10 . The structure of 9 was established by X-ray crystal-structure analysis.     

A convenient approach to heterocyclic building blocks: synthesis of novel ring systems containing a [5,6]Pyrano[2,3-c]pyrazol-4(1H)-one moiety

Starting from commercially available educts, a straightforward synthetic route to new heterocyclic building blocks is exemplified with the one- or two-step synthesis of tri-, tetra-, or pentacyclic ring systems. Representatives of the following novel ring systems are prepared from 3-methyl-1-phenyl-2-pyrazolin-5-one and the corresponding o-halo-arenecarbonyl chloride using calcium hydroxide in refluxing 1,4-dioxane: pyrimidino[4',5':5,6]pyrano[2,3-c]pyrazol-4(1H)-one, thieno[3',2':5,6]pyrano[2,3c]pyrazol- 4-(1H)-one, thieno[3',4':5,6]pyrano[2,3-c]pyrazol-4(1H)-one, thieno[3',2':4',5']thieno[2',3':5,6]-pyrano[2,3-c]pyrazol-4(1H)-one, [1,3]dioxolo[5',6'][1]benzothieno[2',3':5,6]pyrano-[2,3-c]- pyrazol-4(1H)-one, pyridazino[4',3':5,6]pyrano[2,3-c]pyrazol-4(1H)-one and pyrazolo-[4',3':5',6']pyrido[3',4':5,6]pyrano[2,3-c]pyrazol-4(1H)-one. While the latter two ring systems are directly obtained due to a spontaneous intramolecular substitution reaction, in the other reactions uncyclised 4-aroylpyrazol-5-ols are produced, which are cyclised into the target heterocycles in a subsequent synthetic step (i.e. treatment with NaH in DMF). Detailed NMR spectroscopic investigations ((1)H-, (13)C-, (15)N-) with the obtained compounds were undertaken to unambiguously prove the new structures.     

Synthesis of some new hetarylpyranopyridazines,cinnolines, and hetarylpyridazine derivatives

4-Acetyl-5,6-diphenylpyridazin-3(2H)-one was condensed with 6-chloro-3-formylchromone under different reaction conditions to yield the enone or pyranopyridazine. Both compounds were used in the synthesis of some new hetarylpyranopyridazines. Pyranodipyridazine was obtained via a sequence of reactions of 4-acetyl-5,6-diphenylpyridazin-3(2H)-one with diethyl carbonate, acetic anhydride, and 4-bromobenzenediazonium chloride. The reactions of pyridazinylbutane-1,3-dione with conc. H2SO4, POCl3, hydrazines, hydroxylamine hydrochloride, cyanoacetamide, thiourea, and thiosemicarbazone were also studied.