共查询到20条相似文献,搜索用时 31 毫秒
1.
Ferdinand Krner Markus Schürmann Hans Preut Wolfgang Kreiser 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(1):76-77
Esterification of a single diastereomer of 2‐(4‐methylenecyclohex‐2‐enyl)propanol, (II), with (1R,4S)‐(+)‐camphanic acid [(1R,4S)‐4,7,7‐trimethyl‐3‐oxo‐2‐oxabicyclo[2.2.1]heptane‐1‐carboxylic acid] leads to the crystalline title compound, C20H28O4. The relative configuration of the camphanate was determined by X‐ray diffraction analysis. The outcome clarifies the relative and absolute stereochemistry of the naturally occurring bisabolane sesquiterpenes β‐turmerone and β‐sesquiphellandrene, since we have converted (II) into both natural products via a stereospecific route. 相似文献
2.
Florence Popowycz Sandrine Gerber‐Lemaire Eliazar Rodriguez‐García Catherine Schütz Pierre Vogel 《Helvetica chimica acta》2003,86(6):1914-1948
The synthesis of 46 derivatives of (2R,3R,4S)‐2‐(aminomethyl)pyrrolidine‐3,4‐diol is reported (Scheme 1 and Fig. 3), and their inhibitory activities toward α‐mannosidases from jack bean (B) and almonds (A) are evaluated (Table). The most‐potent inhibitors are (2R,3R,4S)‐2‐{[([1,1′‐biphenyl]‐4‐ylmethyl)amino]methyl}pyrrolidine‐3,4‐diol ( 3fs ; IC50(B)=5 μM , Ki=2.5 μM ) and (2R,3R,4S)‐2‐{[(1R)‐2,3‐dihydro‐1H‐inden‐1‐ylamino]methyl}pyrrolidine‐3,4‐diol ( 3fu ; IC50(B)=17 μM , Ki=2.3 μM ). (2S,3R,4S)‐2‐(Aminomethyl)pyrrolidine‐3,4‐diol ( 6 , R?H) and the three 2‐(N‐alkylamino)methyl derivatives 6fh, 6fs , and 6f are prepared (Scheme 2) and found to inhibit also α‐mannosidases from jack bean and almonds (Table). The best inhibitor of these series is (2S,3R,4S)‐2‐{[(2‐thienylmethyl)amino]methyl}pyrrolidine‐3,4‐diol ( 6o ; IC50(B)=105 μM , Ki=40 μM ). As expected (see Fig. 4), diamines 3 with the configuration of α‐D ‐mannosides are better inhibitors of α‐mannosidases than their stereoisomers 6 with the configuration of β‐D ‐mannosides. The results show that an aromatic ring (benzyl, [1,1′‐biphenyl]‐4‐yl, 2‐thienyl) is essential for good inhibitory activity. If the C‐chain that separates the aromatic system from the 2‐(aminomethyl) substituent is longer than a methano group, the inhibitory activity decreases significantly (see Fig. 7). This study shows also that α‐mannosidases from jack bean and from almonds do not recognize substrate mimics that are bulky around the O‐glycosidic bond of the corresponding α‐D ‐mannopyranosides. These observations should be very useful in the design of better α‐mannosidase inhibitors. 相似文献
3.
Ferdinand Krner Markus Schürmann Hans Preut Wolfgang Kreiser 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(1):74-75
Stereoselective hydroboration of (?)‐isopulegol and subsequent fractional crystallization furnishes the title compound, C10H20O2. The relative configuration of the stereogenic centres has been assigned by means of X‐ray diffraction analysis since the monoterpenediol is employed as a versatile chiral building block in stereospecific natural product synthesis. 相似文献
4.
Hiroshi Katagiri Masao Morimoto Kenichi Sakai 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(7):o357-o360
The structures of diastereomeric pairs consisting of (S)‐ and (R)‐2‐methylpiperazine with (2S,3S)‐tartaric acid are both 1:1 salts, namely (S)‐2‐methylpiperazinium (2S,3S)‐tartrate dihydrate, C5H14N22+·C4H4O62−·2H2O, (I), and (R)‐2‐methylpiperazinium (2S,3S)‐tartrate dihydrate, C5H14N22+·C4H4O62−·2H2O, (II), which reveal the formation of well defined ammonium carboxylate salts linked via strong intermolecular hydrogen bonds. Unlike the situation in the more soluble salt (II), the alternating columns of tartrate and ammonium ions of the less soluble salt (I) are packed neatly in a grid around the a axis, which incorporates water molecules at regular intervals. The increased efficiency of packing for (I) is evident in its lower `packing coefficient', and the hydrogen‐bond contribution is stronger in the more soluble salt (II). 相似文献
5.
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
6.
Jarno Kansikas Kaija Sipil 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(11):1383-1385
In the synthesis of 1‐phenyl‐2‐phenylthio‐2‐(tetrahydropyran‐2‐ylthio)ethanol, C19H22O2S2, four diastereoisomers are formed. Two non‐centrosymmetric enantiomeric forms which crystallize in space groups P212121 and Pna21 are presented. The former has an intramolecular hydrogen bond between the hydroxyl group and the O atom of the tetrahydropyran ring. In the latter isomer, the hydroxyl group forms an intermolecular hydrogen bond to the O atom of the tetrahydropyranyl group of a neighbouring molecule, joining the molecules into chains in the c‐axis direction; the O?O distances are 2.962 (4) and 2.764 (3) Å, respectively. The tetrahydropyran rings are in chair conformations in both isomers and the S side chain has an equatorial orientation in the former, but an axial orientation in the latter molecule. 相似文献
7.
Jing‐Jing Nie Duan‐Jun Xu Zi‐Qiang Hu Yuan‐Zhi Xu Jing‐Yun Wu Michael Y. Chiang 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(2):o106-o107
The title chiral compound, 3‐aminocarbonyl‐1,2,2‐trimethylcyclopentane‐1‐carboxylic acid, C10H17NO3, was prepared from (1R,3S)‐camphoric acid. The five‐membered ring adopts a conformation which is intermediate between a twist and an envelope. Elongations of the C—C bonds and contractions of the C—C—C bond angles are observed within the five‐membered ring. A 1H NMR spectrum was recorded to assist in distinguishing the amide group from the carboxyl group. 相似文献
8.
Wei Huang Hui‐Fen Qian Yi‐Hu Chen Shao‐Hua Gou Yi‐Zhi Li 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(8):o479-o480
The title compound, (1S,3R)‐3‐carbamoyl‐2,2,3‐trimethylcyclopentane‐1‐carboxylic acid, C10H17NO3, was synthesized and characterized by IR, EA, ES–MS (electrospray ionization mass spectra), 1H NMR, 13C NMR and X‐ray diffraction techniques. The two independent molecules form a two‐dimensional network via O—H⃛O and N—H⃛O hydrogen‐bonding interactions between their carboxylic acid and carbamoyl groups. 相似文献
9.
Ove Alexander Hgmoen strand Zeshan Iqbal Marcel Sandberg Eili T. Kase Carl Henrik Grbitz Pl Rongved 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(6):647-650
(2S,3S)‐2,6‐Dimethylheptane‐1,3‐diol, C9H20O2, (I), was synthesized from the ketone (R)‐4‐benzyl‐3‐[(2R,3S)‐3‐hydroxy‐2,6‐dimethylheptanoyl]‐1,3‐oxazolidin‐2‐one, C19H27NO4, (II), containing C atoms of known chirality. In both structures, strong hydrogen bonds between the hydroxy groups form tape motifs. The contribution from weaker C—H...O hydrogen bonds is much more evident in the structure of (II), which furthermore contains an example of a direct short Osp3...Csp2 contact that represents a usually unrecognized type of intermolecular interaction. 相似文献
10.
F. Sbai M. Dakir A. Auhmani H. El Jamili M. Akssira A. Benharref A. Kenz M. Pierrot 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(8):o518-o520
The stereochemistries of the title compounds, both C16H24Cl2O, have been established by X‐ray diffraction. In both structures, the seven‐membered ring adopts the same conformation, whereas the six‐membered ring shows an envelope conformation in the epoxydodecane structure and a boat conformation in the dodecan‐9‐one structure. 相似文献
11.
Jaime Vzquez Sylvain Berns Ruth Melndrez Roberto Portillo Ren Gutirrez 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(9):m424-m427
The title compounds, trans‐dichlorobis[(1R,2R,3R,5S)‐(−)‐2,6,6‐trimethylbicyclo[3.1.1]heptan‐3‐amine]palladium(II), [PdCl2(C10H19N)2], and trans‐dichlorobis[(1S,2S,3S,5R)‐(+)‐2,6,6‐trimethylbicyclo[3.1.1]heptan‐3‐amine]palladium(II) hemihydrate, [PdCl2(C10H19N)2]·0.5H2O, present different arrangements of the amine ligands coordinated to PdII, viz. antiperiplanar in the former case and (−)anticlinal in the latter. The hemihydrate is an inclusion compound, with a Pd coordination complex and disordered water molecules residing on crystallographic twofold axes. The crystal structure for the hemihydrate includes a short Pd⋯Pd separation of 3.4133 (13) Å. 相似文献
12.
Cyclodipepflde (3S, 6S )-bis (phenylmethyl) piperazlne-2,5-dione was prelmred in high yield by heating phenylalanine methyl ester in toluene under reflux. The reduction of this cydodipeptide with sodium NaBH4-BF3 in DIME gave the (2S ,SS)-bis(phenyl-methyl)plperazine, which, on heating with ethylene bromide and triethyiamine, afforded the title compounds. This methodwas proved to be generally applicable to the synthesis of C2-symmetric 2, 5-disubsiituted=l, 4-diazabicyclo [ 2.2.2 ] octanefrom the corresponding natural or unnatural amino acid esters. 相似文献
13.
Three diastereomeric second‐generation (G2) dendrons were prepared by using (2S,4S)‐, (2S,4R)‐, and (2R,4S)‐4‐aminoprolines on the multigram scale with highly optimized and fully reproducible solution‐phase methods. The peripheral 4‐aminoproline branching units of all the dendrons have the 2S,4S configuration throughout, whereas those units at the focal point have the 2S,4S, 2S,4R, and 2R,4S configurations. These latter configurations led to the dendrons being named (2S,4S)‐ 1 , (2S,4R)‐ 1 , and (2R,4S)‐ 1 , respectively. The 4‐aminoproline derivatives used in this study are new, although many closely related compounds exist. Their syntheses were optimized. The dendron assembly involved amide coupling, the efficiency of which was also optimized by employing the following well‐known reagents: EDC/HOBt, DCC/HOSu, TBTA/HOBt, TBTU/HOBt, BOP/HOBt, pentafluorophenol, and PyBOP/HOBt. It was found that the use of PyBOP is by far the best for dendrons (2S,4S)‐ 1 and (2R,4S)‐ 1 , and pentafluorophenol active ester is best for (2S,4R)‐ 1 . Because of their multigram scale, all couplings were done in solution instead of by solid‐phase procedures. Purifications were, nevertheless, easy. The optical purities of the key intermediates as well as the three G2 dendrons were analyzed by chiral HPLC analysis. These novel, diastereomeric second‐generation dendrons have a rather compact and conformationally highly rigid structure that makes them interesting candidates for applications, for example, in the field of dendronized polymers and in organocatalysis. 相似文献
14.
Yoann Coquerel Aurlien Blanc Jean‐Pierre Deprs Andrew E. Greene Marie‐Thrse Averbuch‐Pouchot Christian Philouze Andr Durif 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(12):1480-1481
The title compound, C12H10Cl4O2, has a pseudoasymmetric centre at the methyl‐substituted carbon and, in the solid state, a boat‐like conformation. 相似文献
15.
Henryk Krawczyk Katarzyna Wsek Jacek Kdzia Jakub Wojciechowski Wojciech M. Wolf 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(1):o24-o26
The cyclopropane ring of the title compound, C17H16O2, shows a high level of substituent‐induced bond‐length asymmetry. The carboxyl group adopts a conformation that prompts electron‐density transfer from the ring towards the carbonyl π system. 相似文献
16.
Two new chiral alcohols, 2(S)‐[2(R)‐methylhexyloxy]propanol ( 5 ) and 2(S)‐[2(S)‐methylhexyloxy]propanol ( 6 ), were prepared from the corresponding propionic acid ethyl ester 1 and 2 in the presence of sodium borohydride. They were used as the chiral moiety for the synthesis of two diastereomeric liquid crystals 7 and 8 . Both of them exhibit the phase sequence I‐SmA‐SmC*‐SmX‐Cr. The mesogenic properties of the (S,S)‐diastereomer 8 are more unique in comparison with those of the (S,R)‐diastereomer 7. It possesses not only lower SmA and SmC* phase transition temperature, 103 °C vs. 112 °C for SmA phase and 31 °C vs. 65 °C for SmC* phase, but wider SmA and SmC* phase range, 40 °C vs. 31 °C for SmA phase and 72 °C vs. 47 °C for SmC* phase. The diastereomer 8 also has a larger Ps value than that of 7, 24 vs. 15 nC cm?2 measured at Tc ‐ T = 10 °C. The difference in these mesogenic properties is discussed by comparing their conformation difference at the molecular part of benzoate. 相似文献
17.
Susanne Flock Clemens Bruhn Heinrich Fink Herbert Frauenrath 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(2):o101-o103
The title enantiomorphic compounds, C16H23NO4S, have been obtained in an enantiomerically pure form by crystallization from a diastereomeric mixture either of (2S,4S)‐ and (2R,4S)‐ or of (2R,4R)‐ and (2S,4R)‐2‐tert‐butyl‐4‐methyl‐3‐(4‐tolylsulfonyl)‐1,3‐oxazolidine‐4‐carbaldehyde. These mixtures were prepared by an aziridination rearrangement process starting with (S)‐ or (R)‐2‐tert‐butyl‐5‐methyl‐4H‐1,3‐dioxine. The crystal structures indicate an envelope conformation of the oxazolidine moiety for both compounds. 相似文献
18.
Marian Koman Peter Szolcsnyi Tibor Gracza 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(4):e138-e138
The absolute configuration at the new stereogenic centre during the key step of the total synthesis was established byX‐ray analysis of the title compound, C7H15NO4+·Cl?. 相似文献
19.
Pedro H. Ferri Carlito Lariucci Leon I. B. Homar Raquel F. Santos Elaine R. Maia Lourivaldo S. Santos Ivo Vencato 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(1):118-120
The crystal structure and absolute configuration of the title compound, C17H21BrO8, have been determined by X‐ray analysis. They confirmed the 1′R absolute configuration at the 1′‐bromoethyl moiety which has been assigned previously on the basis of chemical and spectroscopic data. Cohesion of the crystal can be attributed to weak intermolecular C—H?O and van der Waals interactions. 相似文献
20.
The First Synthesis of (4S,5R,6R)‐5,6‐Dihydroxy‐4‐(prop‐1‐en‐2‐yl)cyclohex‐1‐ene‐1‐carboxylic Acid 下载免费PDF全文
Oleg V. Ardashov Yuliya S. Demidova Dina V. Korchagina Konstantin P. Volcho Irina L. Simakova Nariman F. Salakhutdinov 《Helvetica chimica acta》2015,98(10):1442-1455
A putative acid metabolite of a novel highly effective antiparkinsonian agent, (4S,5R,6R)‐5,6‐dihydroxy‐4‐(prop‐1‐en‐2‐yl)cyclohex‐1‐ene‐1‐carboxylic acid ( 5 ), was synthesized for the first time. Several synthetic approaches based on different transformations of O‐bearing monoterpenoids of the pinane and p‐menthane series were developed and tested in the course of the study. Acid 5 was synthesized starting from a commercially available monoterpenoid, (?)‐verbenone, in a total yield of 4.4% over eight steps. 相似文献