共查询到20条相似文献,搜索用时 109 毫秒
1.
Tullio Pilati Gianluigi Casalone 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(3):o178-o180
The title diastereoisomers, methyl 5‐(S)‐[2‐(S)‐methoxycarbonyl)‐2,3,4,5‐tetrahydropyrrol‐1‐ylcarbonyl]‐1‐(4‐methylphenyl)‐4,5‐dihydropyrazole‐3‐carboxylate and methyl 5‐(S)‐[2‐(R)‐methoxycarbonyl)‐2,3,4,5‐tetrahydropyrrol‐1‐ylcarbonyl]‐1‐(4‐methylphenyl)‐4,5‐dihydropyrazole‐3‐carboxylate, both C19H23N3O5, have been studied in two crystalline forms. The first form, methyl 5‐(S)‐[2‐(S)‐methoxycarbonyl)‐2,3,4,5‐tetrahydropyrrol‐1‐ylcarbonyl]‐1‐(4‐methylphenyl)‐4,5‐dihydropyrazole‐3‐carboxylate–methyl 5‐(S)‐[2‐(R)‐methoxycarbonyl)‐2,3,4,5‐tetrahydropyrrol‐1‐ylcarbonyl]‐1‐(4‐methylphenyl)‐4,5‐dihydropyrazole‐3‐carboxylate (1/1), 2(S),5(S)‐C19H23N3O5·2(R),5(S)‐C19H23N3O5, contains both S,S and S,R isomers, while the second, methyl 5‐(S)‐[2‐(S)‐methoxycarbonyl)‐2,3,4,5‐tetrahydropyrrol‐1‐ylcarbonyl]‐1‐(4‐methylphenyl)‐4,5‐dihydropyrazole‐3‐carboxylate, 2(S),5(S)‐C19H23N3O5, is the pure S,S isomer. The S,S isomers in the two structures show very similar geometries, the maximum difference being about 15° on one torsion angle. The differences between the S,S and S,R isomers, apart from those due to the inversion of one chiral centre, are more remarkable, and are partially due to a possible rotational disorder of the 2‐(methoxycarbonyl)tetrahydropyrrole group. 相似文献
2.
Yun‐Mei Bi Xu‐Bin Bi Qian‐Rong Zhao Yuan‐Teng Chen Jin‐Lun Xie 《Helvetica chimica acta》2004,87(11):2890-2895
Four novel dihydroisocoumarin (=3,4‐dihydro‐1H‐2‐benzopyran‐1‐one) glucosides were isolated from a culture broth of a strain of the fungus Cephalosporium sp. AL031. Their structures were elucidated as (2E,4E)‐5‐[(3S)‐5‐acetyl‐8‐(β‐D ‐glucopyranosyloxy)‐3,4‐dihydro‐6‐hydroxy‐1‐oxo‐1H‐2‐benzopyran‐3‐yl]penta‐2,4‐dienal ( 1 ), (2E,4E)‐5‐[(3S)‐5‐acetyl‐8‐(β‐D ‐glucopyranosyloxy)‐3,4‐dihydro‐6‐methoxy‐1‐oxo‐1H‐2‐benzopyran‐3‐yl]penta‐2,4‐dienal ( 2 ), (3S)‐8‐(β‐D ‐glucopyranosyloxy)‐3‐[(1E,3E,5E)‐hepta‐1,3,5‐trienyl]‐3,4‐dihydro‐6‐hydroxy‐5‐methyl‐1H‐2‐benzopyran‐1‐one ( 3 ), and (3S)‐8‐[(6‐O‐acetyl‐β‐D ‐glucopyranosyl)oxy]‐3‐[(1E,3E,5E)‐hepta‐1,3,5‐trienyl]‐3,4‐dihydro‐6‐methoxy‐5‐methyl‐1H‐2‐benzopyran‐1‐one ( 4 ) by spectroscopic methods, including 2D‐NMR techniques and chemical methods. 相似文献
3.
Asymmetric syntheses of the following 17‐membered macrocyclic spermine alkaloids are presented: (−)‐(S)‐protoverbine (=(8S)‐8‐phenyl‐1,5,9,13‐tetraazacycloheptadecane‐6‐one; 1 ), (+)‐(S)‐protomethine (=(2S)‐2‐phenyl‐1,5,9,14‐tetraazabicyclo[12.3.1]octadecan‐4‐one; 2 ), (−)‐(S)‐buchnerine (=(8S)‐8‐(4‐methoxyphenyl)‐1,5,9,13‐tetraazacycloheptadecane‐6‐one; 8 ), (+)‐(S)‐verbamethine (=(+)‐(2S)‐9‐[(E)‐phenylprop‐2‐enoyl]‐2‐phenyl‐1,5,9,14‐tetraazabicyclo[12.3.1]octadecan‐4‐one; 4 ), (−)‐(S)‐verbacine (=(−)‐(8S)‐1‐[(E)‐phenylprop‐2‐enoyl]‐8‐phenyl‐1,5,9,13‐tetraazacycloheptadecan‐6‐one; 3 ), (−)‐(S)‐verbasikrine (=(−)‐(8S)‐1‐[(E)‐3‐(4‐methoxyphenyl)prop‐2‐enoyl]‐8‐phenyl‐1,5,9,13‐tetraazacycloheptadecan‐6‐one; 26 ), (−)‐(S)‐isoverbasikrine (=(−)‐(8S)‐1‐[(Z)‐3‐(4‐methoxyphenyl)prop‐2‐enoyl]‐8‐phenyl‐1,5,9,13‐tetraazacycloheptadecan‐6‐one; 25 ), (+)‐(S)‐verbamekrine (=(+)‐(2S)‐9‐[(E)‐3‐(4‐methoxyphenyl)prop‐2‐enoyl]‐2‐phenyl‐1,5,9,14‐tetraazabicyclo[12.3.1]octadecan‐4‐one; 23 ), and (+)‐(S)‐isoverbamekrine (=(+)‐(2S)‐9‐[(Z)‐3‐(4‐methoxyphenyl)prop‐2‐enoyl]‐2‐phenyl‐1,5,9,14‐tetraazabicyclo[12.3.1]octadecan‐4‐one; 24 ). Effective methods for 1H‐NMR determination of the enantiomeric purity in which (S)‐2‐hydroxy‐2‐phenylacetic acid and (S)‐2‐acetoxy‐2‐phenylacetic acid are used as shift reagents for 1, 8 , and related macrocyclic alkaloids are described. 相似文献
4.
Jzsef Deli Erzsbet
sz Júlia Visy Ferenc Zsila Mikls Simonyi Gyula Tth 《Helvetica chimica acta》2001,84(1):263-270
The (3R,5′R,6′R)‐ and (3R,5′R,6′S)‐capsanthol‐3′‐one (=3,6′‐dihydroxy‐β,κ‐caroten‐3′‐one; 4 and 5 , resp.) were reduced by different complex metal hydrides containing organic ligands. The ratio of the thus obtained diastereoisomeric (3′S)‐capsanthols 2 and 3 or (3′R)‐capsanthols 6 and 7 , respectively, was investigated. Four complex hydrides showed remarkable stereoselectivity and produced the (3′R,6′S)‐capsanthol ( 6 ) in 80 – 100% (see Table 1). The starting materials and the products were characterized by UV/VIS, CD, 1H‐ and 13C‐NMR, and mass spectra. 相似文献
5.
Anthony Linden J. E. Florian Magirius Heinz Heimgartner 《Acta Crystallographica. Section C, Structural Chemistry》2020,76(1):1-9
Depsipeptides and cyclodepsipeptides are analogues of the corresponding peptides in which one or more amide groups are replaced by ester functions. Reports of crystal structures of linear depsipeptides are rare. The crystal structures and conformational analyses of four depsipeptides with an alternating sequence of an α,α‐disubstituted α‐amino acid and an α‐hydroxy acid are reported. The molecules in the linear hexadepsipeptide amide in (S)‐Pms‐Acp‐(S)‐Pms‐Acp‐(S)‐Pms‐Acp‐NMe2 acetonitrile solvate, C47H58N4O9·C2H3N, ( 3b ), as well as in the related linear tetradepsipeptide amide (S)‐Pms‐Aib‐(S)‐Pms‐Aib‐NMe2, C28H37N3O6, ( 5a ), the diastereoisomeric mixture (S,R)‐Pms‐Acp‐(R,S)‐Pms‐Acp‐NMe2/(R,S)‐Pms‐Acp‐(R,S)‐Pms‐Acp‐NMe2 (1:1), C32H41N3O6, ( 5b ), and (R,S)‐Mns‐Acp‐(S,R)‐Mns‐Acp‐NMe2, C30H37N3O6, ( 5c ) (Pms is phenyllactic acid, Acp is 1‐aminocyclopentanecarboxylic acid and Mns is mandelic acid), generally adopt a β‐turn conformation in the solid state, which is stabilized by intramolecular N—H…O hydrogen bonds. Whereas β‐turns of type I (or I′) are formed in the cases of ( 3b ), ( 5a ) and ( 5b ), which contain phenyllactic acid, the torsion angles for ( 5c ), which incorporates mandelic acid, indicate a β‐turn in between type I and type III. Intermolecular N—H…O and O—H…O hydrogen bonds link the molecules of ( 3a ) and ( 5b ) into extended chains, and those of ( 5a ) and ( 5c ) into two‐dimensional networks. 相似文献
6.
Samo Pirc Simon Re
nik Marko kof Jurij Svete Ljubo Goli
Anton Meden Branko Stanovnik 《Journal of heterocyclic chemistry》2002,39(2):411-416
Dedicated to Professor Emeritus Miha Ti?ler on the occasion of his 75th birthday Treatment of methyl (S)‐5‐[(E)‐(dimethylamino)methylidene]‐2‐oxotetrahydrofuran‐5‐carboxylate ( 2 ) with potassium cyanide in acetic acid gave (S)‐5‐[(E)‐cyanomethylidene]‐2‐oxotetrahydrofuran‐5‐car‐boxylate ( 3 ), which was used as chiral dipolarophile in 1,3‐dipolar cycloadditions. Reactions of 3 with diazomethane ( 4 ) and nitrile oxides 5a‐c afforded spirolactones 6–8 in 24‐34% diastereomeric excess, while with diazomethane ( 4 ) in the presence of triethylamine, methyl 3‐cyanomethyl‐2‐methoxyfuran‐5‐carboxylate ( 12 ) was obtained. 相似文献
7.
Biotransformation of (±)‐threo‐7,8‐dihydroxy(7,8‐2H2)tetradecanoic acids (threo‐(7,8‐2H2)‐ 3 ) in Saccharomyces cerevisiae afforded 5,6‐dihydroxy(5,6‐2H2)dodecanoic acids (threo‐(5,6‐2H2)‐ 4 ), which were converted to (5S,6S)‐6‐hydroxy(5,6‐2H2)dodecano‐5‐lactone ((5S,6S)‐(5,6‐2H2)‐ 7 ) with 80% e.e. and (5S,6S)‐5‐hydroxy(5,6‐2H2)dodecano‐6‐lactone ((5S,6S)‐5,6‐2H2)‐ 8 ). Further β‐oxidation of threo‐(5,6‐2H2)‐ 4 yielded 3,4‐dihydroxy(3,4‐2H2)decanoic acids (threo‐(3,4‐2H2)‐ 5 ), which were converted to (3R,4R)‐3‐hydroxy(3,4‐2H2)decano‐4‐lactone ((3R,4R)‐ 9 ) with 44% e.e. and converted to 2H‐labeled decano‐4‐lactones ((4R)‐(3‐2H1)‐ and (4R)‐(2,3‐2H2)‐ 6 ) with 96% e.e. These results were confirmed by experiments in which (±)‐threo‐3,4‐dihydroxy(3,4‐2H2)decanoic acids (threo‐(3,4‐2H2)‐ 5 ) were incubated with yeast. From incubations of methyl (5S,6S)‐ and (5R,6R)‐5,6‐dihydroxy(5,6‐2H2)dodecanoates ((5S,6S)‐ and (5R,6R)‐(5,6‐2H2)‐ 4a ), the (5S,6S)‐enantiomer was identified as the precursor of (4R)‐(3‐2H1)‐ and (2,3‐2H2)‐ 6 ). Therefore, (4R)‐ 6 is synthesized from (3S,4S)‐ 5 by an oxidation/keto acid reduction pathway involving hydrogen transfer from C(4) to C(2). In an analogous experiment, methyl (9S,10S)‐9,10‐dihydroxyoctadecanoate ((9S,10S)‐ 10a ) was metabolized to (3S,4S)‐3,4‐dihydroxydodecanoic acid ((3S,4S)‐ 15 ) and converted to (4R)‐dodecano‐4‐lactone ((4R)‐ 18 ). 相似文献
8.
Marko kof Jurij Svete Branko Stanovnik Simona Goli
‐Grdadolnik 《Helvetica chimica acta》2000,83(4):760-766
(3E,5S)‐1‐Benzoyl‐5‐[(benzoyloxy)methyl]‐3‐[(dimethylamino)methylidene]pyrrolidin‐2‐one ( 9 ) was prepared in two steps from commercially available (S)‐5‐(hydroxymethyl)pyrrolidin‐2‐one ( 7 ) (Scheme 1). Compound 9 gave, in one step, upon treatment with various C,N‐ and C,O‐1,3‐dinucleophiles 10 – 18 , the corresponding 3‐(quinolizin‐3‐yl)‐ and 3‐(2‐oxo‐2H‐pyran‐3‐yl)‐substituted (2S)‐2‐(benzoylamino)propyl benzoates 19 – 27 (Schemes 1 and 2). 相似文献
9.
The chiral compounds (R)‐ and (S)‐1‐benzoyl‐2,3,5,6‐tetrahydro‐3‐methyl‐2‐(1‐methylethyl)pyrimidin‐4(1H)‐one ((R)‐ and (S)‐ 1 ), derived from (R)‐ and (S)‐asparagine, respectively, were used as convenient starting materials for the preparation of the enantiomerically pure α‐alkylated (alkyl=Me, Et, Bn) α,β‐diamino acids (R)‐ and (S)‐ 11 – 13 . The chiral lithium enolates of (R)‐ and (S)‐ 1 were first alkylated, and the resulting diasteroisomeric products 5 – 7 were aminated with ‘di(tert‐butyl) azodicarboxylate’ (DBAD), giving rise to the diastereoisomerically pure (≥98%) compounds 8 – 10 . The target compounds (R)‐ and (S)‐ 11 – 13 could then be obtained in good yields and high purities by a hydrolysis/hydrogenolysis/hydrolysis sequence. 相似文献
10.
V. Percec A. D. Asandei Q. Zheng 《Journal of polymer science. Part A, Polymer chemistry》2000,38(19):3631-3655
(S)‐1‐Cyano‐2‐methylpropyl‐4′‐{[4‐(8‐vinyloxyoctyloxy)benzoyl]oxy}biphenyl‐ 4‐carboxylate [ (S)‐11 ] and (R)‐1‐cyano‐2‐methylpropyl‐4′‐{[4‐(8‐vinyloxyoctyloxy)benzoyl]oxy}biphenyl‐4‐carboxylate [( R)‐11 ] enantiomers, both greater than 99% enantiomeric excess, and their corresponding homopolymers, poly[ (S)‐11 ] and poly[ (R)‐11 ], with well‐defined molecular weights and narrow molecular weight distributions were synthesized and characterized. The mesomorphic behaviors of (S)‐11 and poly[ (S)‐11 ] are identical to those of (R)‐11 and poly[ (R)‐11 ], respectively. Both (S)‐11 and (R)‐11 exhibit enantiotropic SA, S, and SX (unidentified smectic) phases. The corresponding homopolymers exhibit SA and S phases. The homopolymers with a degree of polymerization (DP) less than 6 also show a crystalline phase, whereas those with a DP greater than 10 exhibit a second SX phase. Phase diagrams were investigated for four different pairs of enantiomers, (S)‐11 /( R)‐11 , (S)‐11 /poly[ (R)‐11 ], and poly[ (S)‐11 ]/poly[ (R)‐11 ], with similar and dissimilar molecular weights. In all cases, the structural units derived from the enantiomeric components are miscible and, therefore, isomorphic in the SA and S phases over the entire range of enantiomeric composition. Chiral molecular recognition was observed in the SA and SX phases of the monomers but not in the SA phase of the polymers. In addition, a very unusual chiral molecular recognition effect was detected in the S phase of the monomers below their crystallization temperature and in the S phase of the polymers below their glass‐transition temperature. In the S phase of the monomers above the melting temperature and of the polymers above the glass‐transition temperature, nonideal solution behavior was observed. However, in the SA phase the monomer–polymer and polymer–polymer mixtures behave as an ideal solution. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3631–3655, 2000 相似文献
11.
The chemical synthesis of deuterated isomeric 6,7‐dihydroxydodecanoic acid methyl esters 1 and the subsequent metabolism of esters 1 and the corresponding acids 1a in liquid cultures of the yeast Saccharomyces cerevisiae was investigated. Incubation experiments with (6R,7R)‐ or (6S,7S)‐6,7‐dihydroxy(6,7‐2H2)dodecanoic acid methyl ester ((6R,7R)‐ or (6S,7S)‐(6,7‐2H2)‐ 1 , resp.) and (±)‐threo‐ or (±)‐erythro‐6,7‐dihydroxy(6,7‐2H2)dodecanoic acid ((±)‐threo‐ or (±)‐erythro‐(6,7‐2H2)‐ 1a , resp.) elucidated their metabolic pathway in yeast (Tables 1–3). The main products were isomeric 2H‐labeled 5‐hydroxydecano‐4‐lactones 2 . The absolute configuration of the four isomeric lactones 2 was assigned by chemical synthesis via Sharpless asymmetric dihydroxylation and chiral gas chromatography (Lipodex ® E). The enantiomers of threo‐ 2 were separated without derivatization on Lipodex ® E; in contrast, the enantiomers of erythro‐ 2 could be separated only after transformation to their 5‐O‐(trifluoroacetyl) derivatives. Biotransformation of the methyl ester (6R,7R)‐(6,7‐2H2)‐ 1 led to (4R,5R)‐ and (4S,5R)‐(2,5‐2H2)‐ 2 (ratio ca. 4 : 1; Table 2). Estimation of the label content and position of (4S,5R)‐(2,5‐2H2)‐ 2 showed 95% label at C(5), 68% label at C(2), and no 2H at C(4) (Table 2). Therefore, oxidation and subsequent reduction with inversion at C(4) of 4,5‐dihydroxydecanoic acid and transfer of 2H from C(4) to C(2) is postulated. The 5‐hydroxydecano‐4‐lactones 2 are of biochemical importance: during the fermentation of Streptomyces griseus, (4S,5R)‐ 2 , known as L‐factor, occurs temporarily before the antibiotic production, and (?)‐muricatacin (=(4R,5R)‐5‐hydroxy‐heptadecano‐4‐lactone), a homologue of (4R,5R)‐ 2 , is an anticancer agent. 相似文献
12.
Enantiomerically pure (+)‐(1S,4S,5S,6S)‐6‐endo‐(benzyloxy)‐5‐exo‐{[(tert‐butyl)dimethylsilyl]oxy}‐7‐oxabicyclo[2.2.1]heptan‐2‐one ((+)‐ 5 ) and its enantiomer (−)‐ 5 , obtained readily from the Diels‐Alder addition of furan to 1‐cyanovinyl acetate, can be converted with high stereoselectivity into 8‐oxabicyclo[3.2.1]octane‐2,3,4,6,7‐pentol derivatives (see 23 – 28 in Scheme 2). A precursor of them, (1R,2S,4R,5S,6S,7R,8R)‐7‐endo‐(benzyloxy)‐8‐exo‐hydroxy‐3,9‐dioxatricyclo[4.2.1.02,4]non‐5‐endo‐yl benzoate ((−)‐ 19 ), is transformed into (1R,2R,5S, 6S,7R,8S)‐6‐exo,8‐endo‐bis(acetyloxy)‐2‐endo‐(benzyloxy)‐4‐oxo‐3,9‐dioxabicyclo[3.3.1]non‐7‐endo‐yl benzoate ((−)‐ 43 ) (see Scheme 5). The latter is the precursor of several protected 2,6‐anhydrohepturonic acid derivatives such as the diethyl dithioacetal (−)‐ 57 of methyl 3,5‐di‐O‐acetyl‐2,6‐anhydro‐4‐O‐benzoyl‐D ‐glycero‐D ‐galacto‐hepturonate (see Schemes 7 and 8). Hydrolysis of (−)‐ 57 provides methyl 3,5‐di‐O‐acetyl‐2,6‐anhydro‐4‐O‐benzoyl‐D ‐glycero‐D ‐galacto‐hepturonate 48 that undergoes highly diastereoselective Nozaki‐Oshima condensation with the aluminium enolate resulting from the conjugate addition of Me2AlSPh to (1S,5S,6S,7S)‐7‐endo‐(benzyloxy)‐6‐exo‐{[(tert‐butyl)dimethylsilyl]oxy}‐8‐oxabicyclo[3.2.1]oct‐3‐en‐2‐one ((−)‐ 13 ) derived from (+)‐ 5 (Scheme 12). This generates a β‐C‐mannopyranoside, i.e., methyl (7S)‐3,5‐di‐O‐acetyl‐2,6‐anhydro‐4‐O‐benzoyl‐7‐C‐[(1R,2S,3R,4S,5R,6S,7R)‐6‐endo‐(benzyloxy)‐7‐exo‐{[(tert‐butyl)dimethylsilyl]oxy}‐4‐endo‐hydroxy‐2‐exo‐(phenylthio)‐8‐oxabicyclo[3.2.1]oct‐3‐endo‐yl]‐L ‐glycero‐D ‐manno‐heptonate ((−)‐ 70 ; see Scheme 12), that is converted into the diethyl dithioacetal (−)‐ 75 of methyl 3‐O‐acetyl‐2,6‐anhydro‐4,5‐dideoxy‐4‐C‐{[methyl (7S)‐3,5,7‐tri‐O‐acetyl‐2,6‐anhydro‐4‐O‐benzoyl‐L ‐glycero‐D ‐manno‐heptonate]‐7‐C‐yl}‐5‐C‐(phenylsulfonyl)‐L ‐glycero‐D ‐galacto‐hepturonate ( 76 ; see Scheme 13). Repeating the Nozaki‐Oshima condensation to enone (−)‐ 13 and the aldehyde resulting from hydrolysis of (−)‐ 75 , a (1→3)‐C,C‐linked trisaccharide precursor (−)‐ 77 is obtained. 相似文献
13.
Pter Molnr Jzsef Deli Gyula Tth Adrian Hberli Hanspeter Pfander 《Helvetica chimica acta》2002,85(5):1327-1339
(all‐E)‐5,6‐Diepikarpoxanthin (=(all‐E,3S,5S,6S,3′R)‐5,6‐dihydro‐β,β‐carotene‐3,5,6,3′‐tetrol; 1 ) was submitted to thermal isomerization and I2‐catalyzed photoisomerization. The structures of the main products, i.e. (9Z)‐ ( 2 ), (9′Z)‐ ( 3 ), (13Z)‐ ( 4 ), (13′Z)‐ ( 5 ), and (15Z)‐5,6‐diepikarpoxanthin ( 6 ), were determined by their UV/VIS, CD, 1H‐NMR, and mass spectra. In addition, (9Z,13′Z)‐ or (13Z,9′Z)‐ ( 7 ), (9Z,9′Z)‐ ( 8 ), and (9Z,13Z)‐ or (9′Z,13′Z)‐5,6‐diepikarpoxanthin ( 9 ) were tentatively identified as minor products of the I2‐catalyzed photoisomerization. 相似文献
14.
Tullio Pilati Gianluigi Casalone 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(4):495-496
(5S,9S,17S)‐17‐Hydroxy‐9(10→5)‐abeo‐estr‐4‐ene‐3,10‐dione, C18H26O3, (II), and (5R,9R,17S)‐17‐hydroxy‐9(10→5)‐abeo‐estr‐4‐ene‐3,10‐dione, C18H26O3, (III), are equimolecular products of the FeII‐induced transposition of 10β‐hydroperoxy‐17β‐hydroxyestr‐4‐en‐3‐one, (I). With respect to reagent molecules, the configuration at C9 is retained for (II) while it is inverted in (III). The conformations of the five‐ and six‐membered rings are compared. 相似文献
15.
Hiroshi Katagiri Masao Morimoto Kenichi Sakai 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(1):o20-o24
The crystal structures of a pair of diastereomeric 1:2 salts of (R)‐ and (S)‐2‐methylpiperazine with (2S,3S)‐tartaric acid, namely (R)‐2‐methylpiperazinediium bis[hydrogen (2S,3S)‐tartrate] monohydrate, (I), and (S)‐2‐methylpiperazinediium bis[hydrogen (2S,3S)‐tartrate] monohydrate, (II), both C5H14N22+·2C4H5O6−·H2O, each reveal the formation of well‐defined head‐to‐tail‐connected hydrogen tartrate chains; these chains are linked into a two‐dimensional sheet via intermolecular hydrogen bonds involving hydroxy groups and water molecules, resulting in a layer structure. The (R)‐2‐methylpiperazinediium ions lie between the hydrogen tartrate layers in the most stable equatorial conformation in (I), whereas in (II), these ions are in an unstable axial position inside the more interconnected layers and form a larger number of intermolecular hydrogen bonds than are observed in (I). 相似文献
16.
Janet M. S. Skakle James L. Wardell Solange M. S. V. Wardell 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(7):787-789
Molecules of diphenyl(2‐thioxo‐1,3‐dithiole‐4,5‐dithiolato‐S,S′)plumbane, [Pb(C3S5)(C6H5)2], are linked into sheets via two intermolecular Pb?Sthione interactions of 3.322 (4) and 3.827 (4) Å; the Pb centre has a distorted octahedral geometry. In contrast, molecules of diphenyl(2‐thioxo‐1,3‐dithiole‐4,5‐dithiolato‐S,S′)stannane, [Sn(C3S5)(C6H5)2], are linked into chains via a single intermolecular Sn—Sthione interaction of 2.8174 (9) Å; the Sn centre has a distorted trigonal‐bipyramidal geometry. 相似文献
17.
Pawe Wagner David L. Officer Maciej Kubicki 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(7):o400-o404
In the crystal structures of four thiophene derivatives, (E)‐3′‐[2‐(anthracen‐9‐yl)ethenyl]‐2,2′:5′,2′′‐terthiophene, C28H18S3, (E)‐3′‐[2‐(1‐pyrenyl)ethenyl]‐2,2′:5′,2′′‐terthiophene, C30H18S3, (E)‐3′‐[2‐(3,4‐dimethoxyphenyl)ethenyl]‐2,2′:5′,2′′‐terthiophene, C22H18O2S3, and (E,E)‐1,4‐bis[2‐(2,2′:5′,2′′‐terthiophen‐3′‐yl)ethenyl]‐2,5‐dimethoxybenzene, C36H26O2S6, at least one of the terminal thiophene rings is disordered and the disorder is of the flip type. The terthiophene fragments are far from being coplanar, contrary to terthiophene itself. The central C—C=C—C fragments are almost planar but the bond lengths suggest slight delocalization within this fragment. The crystal packing is determined by van der Waals interactions and some weak, relatively short, C—H...S and C—H...π directional contacts. 相似文献
18.
Jinqing Qu Toru Fujii Toru Katsumata Yuji Suzuki Masashi Shiotsuki Fumio Sanda Masaharu Satoh Jun Wada Toshio Masuda 《Journal of polymer science. Part A, Polymer chemistry》2007,45(23):5431-5445
2,2,6,6‐Tetramethyl‐1‐piperidinyloxy (TEMPO)‐ and 2,2,5,5‐tetramethyl‐1‐pyrrolidinyloxy (PROXYL)‐containing (R)‐1‐methylpropargyl TEMPO‐4‐carboxylate ( 1 ), (R)‐1‐methylpropargyl PROXYL‐3‐carboxylate ( 2 ), (rac)‐1‐methylpropargyl PROXYL‐3‐carboxylate ( 3 ), (S)‐1‐propargylcarbamoylethyl TEMPO‐4‐carboxylate ( 4 ), and (S)‐1‐propargyloxycarbonylethyl TEMPO‐4‐carboxylate ( 5 ) (TEMPO, PROXYL) were polymerized to afford novel polymers containing the TEMPO and PROXYL radicals at high densities. Monomers 1–3 and 5 provided polymers with moderate number‐average molecular weights of 8200–140,900 in 49–97% yields in the presence of (nbd)Rh+[η6‐C6H5B?(C6H5)3], whereas 4 gave no polymer with this catalyst but gave polymers possessing low Mn (3800–7500) in 56–61% yield with [(nbd)RhCl]2‐Et3N. Poly( 1 ), poly( 2 ), and poly( 4 ) took a helical structure with predominantly one‐handed screw sense in THF and CHCl3 as well as in film state. The helical structure of poly( 1 ) and poly( 2 ) was stable upon heating and addition of MeOH, whereas poly( 4 ) was responsive to heat and solvents. All of the free radical‐containing polymers displayed the reversible charge/discharge processes, whose capacities were in a range of 43.2–112 A h/kg. In particular, the capacities of poly( 2 )–poly( 5 )‐based cells reached about 90–100% of the theoretical values regardless of the secondary structure of the polymer, helix and random. Poly( 1 ), poly( 2 ), and poly( 4 ) taking a helical structure exhibited better capacity tolerance towards the increase of current density than nonhelical poly( 3 ) and poly( 5 ) did. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5431–5445, 2007 相似文献
19.
Grzegorz Mlostoń Paulina Mucha Katarzyna Urbaniak Karolina Broda Heinz Heimgartner 《Helvetica chimica acta》2008,91(2):232-238
The three‐component reaction of (R)‐ or (S)‐1‐phenylethylamine ( 6 ), formaldehyde, and an α‐(hydroxyimino) ketone 5 , i.e., 3‐(hydroxyimino)butan‐2‐one ( 5a ) or 2‐(hydroxyimino)‐1,2‐diphenylethanone ( 5b ), yields the corresponding enantiomerically pure 1‐(1‐phenylethyl)‐1H‐imidazole 3‐oxide 7 in high yield (Schemes 2 and 3). The reactions are carried out either in MeOH or in AcOH. Smooth transformations of the N‐oxides into optically active 1‐(1‐phenylethyl)‐1H‐imidazoles 10 and 2,3‐dihydro‐1‐(1‐phenylethyl)‐1H‐imidazole‐2‐thiones 11 are achieved by treatment of 7 with Raney‐Ni and 2,2,4,4‐tetramethyl‐3‐thioxocyclobutanone ( 12 ), respectively (Scheme 4). 相似文献
20.
((?)‐Menthyl (S)‐6′‐acrylyl‐2′‐methyloxy‐1,1′‐binaphthalene‐2‐carboxylate ( 3 ) was synthesized and anionically polymerized using n‐BuLi as an initiator in toluene. The monomer 3 was levorotatory and had an [α]D25 value of ?72.4, but its corresponding polymer poly‐ 3 was dextrorotatory and showed an [α]D25 value of +162.0. Poly‐ 3 was confirmed to exist in the form of one‐handed helical structure in solution by means of comparing the specific optical rotation and the CD spectra with that of 3 and the model compounds such as (?)‐menthyl (S)‐6′‐propionyl‐2′‐methyloxy‐1,1′‐binaphthalene‐2‐carboxylate 2b and (?)‐menthyl (S)‐6′‐heptanoyl‐2′‐methyloxy‐1,1′‐binaphthalene‐2‐carboxylate 2c . This conclusion was also confirmed by the fact that the g‐value of poly‐ 3 is about 11 times of that of monomer 3 . 相似文献