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1.
Elbieta Jankowska Mirosaw Gilski Mariusz Jasklski Zbigniew Grzonka Leszek ankiewicz 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(6):o353-o354
The crystal structure of the title compound, alternatively called 3‐[4‐(benzyloxy)phenyl]‐2‐(N‐tert‐butoxycarbonyl‐N‐methylamino)propionic acid, C22H27NO5, has been studied in order to examine the role of N‐methylation as a determinant of peptide conformation. The conformation of the tert‐butoxycarbonyl group is trans–trans. The side chain has a folded conformation and the two phenyl rings are effectively perpendicular to one another. The carboxylate hydroxyl group and the urethane carbonyl group form a strong intermolecular O—H?O hydrogen bond. 相似文献
2.
Thanikasalam Kanagasabapathy Panchanatheswaran Krishnaswamy Jeyaraman Ramasubbu 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(11):o579-o582
rac‐5‐Diphenylacetyl‐2,2,4‐trimethyl‐2,3,4,5‐tetrahydro‐1,5‐benzothiazepine, C26H27NOS, (I), and rac‐5‐formyl‐2,2,4‐trimethyl‐2,3,4,5‐tetrahydro‐1,5‐benzothiazepine, C13H17NOS, (II), are both characterized by a planar configuration around the heterocyclic N atom. In contrast with the chair conformation of the parent benzothiazepine, which has no substituents at the heterocyclic N atom, the seven‐membered ring adopts a boat conformation in (I) and a conformation intermediate between boat and twist‐boat in (II). The molecules lack a symmetry plane, indicating distortions from the perfect boat or twist‐boat conformations. The supramolecular architectures are significantly different, depending in (I) on C—H...O interactions and intermolecular S...S contacts, and in (II) on a single aromatic π–π stacking interaction. 相似文献
3.
Vladimir N. Nesterov David J. Wiedenfeld Svitlana V. Nesterova Lucas F. Hastings 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(12):o705-o708
The syntheses, X‐ray structural investigations and calculations of the conformational preferences of the carbonyl substituent with respect to the pyran ring have been carried out for the two title compounds, viz. C15H14N2O2, (II), and C20H16N2O2·C2H3N, (III), respectively. In both molecules, the heterocyclic ring adopts a flattened boat conformation. In (II), the carbonyl group and a double bond of the heterocyclic ring are syn, but in (III) they are anti. The carbonyl group forms a short contact with a methyl group H atom in (II). The dihedral angles between the pseudo‐axial phenyl substituent and the flat part of the pyran ring are 92.7 (1) and 93.2 (1)° in (II) and (III), respectively. In the crystal structure of (II), intermolecular N—H⋯N and N—H⋯O hydrogen bonds link the molecules into a sheet along the (103) plane, while in (III), they link the molecules into ribbons along the a axis. 相似文献
4.
Abstract. The five‐membered heteroelement cluster THF · Cl2In(OtBu)3Sn reacts with the sodium stannate [Na(OtBu)3Sn]2 to produce either the new oxo‐centered alkoxo cluster ClInO[Sn(OtBu)2]3 ( 1 ) (in low yield) or the heteroleptic alkoxo cluster Sn(OtBu)3InCl3Na[Sn(OtBu)2]2 ( 2 ). X‐ray diffraction analyses reveal that in compound 1 the polycyclic entity is made of three tin atoms which together with a central oxygen atom form a trigonal, almost planar triangle, perpendicular to which a further indium atom is connected through the oxygen atom. The metal atoms thus are arranged in a Sn3In pyramid, the edges of which are all saturated by bridging tert‐butoxy groups. The indium atom has a further chloride ligand. Compound 2 has two trigonal bipyramids as building blocks which are fused together at a six coordinate indium atom. One of the bipyramids is of the type SnO3In with tert‐butyl groups on the oxygen atoms, while the other has the composition InCl3Na with chlorine atoms connecting the two metals. The sodium atom in 2 has further contacts to two plus one alkoxide groups which are part of a[Sn(OtBu)2]2 dimer disposing of a Sn2O2 central cycle. The hetero element cluster in 2 thus combines three closed entities and its skeleton SnO3InCl3NaO2Sn2O2 consists of three different metallic and two different non‐metallic elements. 相似文献
5.
Clair Bilton Judith A. K. Howard N. N. Laxmi Madhavi Gautam R. Desiraju Frank H. Allen 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(11):1356-1358
The title compounds, C8H10O2, (I), and C12H14O2, (II), occurred as by‐products in the controlled synthesis of a series of bis(gem‐alkynols), prepared as part of an extensive study of synthon formation in simple gem‐alkynol derivatives. The two 4‐(gem‐alkynol)‐1‐ones crystallize in space group P21/c, (I) with Z′ = 1 and (II) with Z′ = 2. Both structures are dominated by O—H?O=C hydrogen bonds, which form simple chains in the cyclohexane derivative, (I), and centrosymmetric dimers, of both symmetry‐independent molecules, in the cyclohexa‐2,5‐diene, (II). These strong synthons are further stabilized by C[triple‐bond]C—H?O=C, Cmethylene—H?O(H) and Cmethyl—H?O(H) interactions. The direct intermolecular interactions between donors and acceptors in the gem‐alkynol group, which characterize the bis(gem‐alkynol) analogues of (I) and (II), are not present in the ketone derivatives studied here. 相似文献
6.
Karsten Gloe Bieluonwu A. Uzoukwu Otto Rademacher 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(12):e580-e581
The title compound, C12H12O2N2·H2O, is described. Although the keto–enol form of the ligand in solution is known, the compound crystallized in the orthorhombic space group P212121 with only the monohydrated 1,3‐diketo form. The intermolecular hydrogen bond between the imino N—H group of the ligand and O atom of the water molecule recorded an H?O distance of 1.73 (3) Å. 相似文献
7.
A study aimed at developing an enantioselective synthesis of the title compound 23 , a 2‐monodeoxy analogue of the naturally occurring (+)‐2‐keto‐3‐deoxy‐D ‐glycero‐D ‐galacto‐2‐nononic acid (KDN), is reported. From D ‐mannose as starting material, the chiral 1,3‐diene 10 , activated by a silyloxy substituent at C(2), was prepared in six steps (Scheme 1). However, the intermediates were often contaminated with varying amounts of by‐products arising from overoxidation during cleavage with periodic acid. An alternative route starting from the inexpensive and readily available D ‐isoascorbic acid ( 12 ), though a little longer than the first, satisfactorily circumvented the purification problem and led to the desired dienes 17 in good yields (scheme 2). The [CoII(S,S)‐(+)‐salen]‐catalyzed hetero‐Diels‐Alder reactions of the aforementioned dienes with ethyl glyoxylate proceeded smoothly at room temperature, giving the dihydropyrano adducts 18 in moderate yields (Scheme 3). Dihydroxylation of 18a followed by reduction of the keto function gave the desired 4,5‐trans dihydroxy moiety of the KDN framework (Scheme 4, see 21 ). The spectroscopic data of the penta‐O‐acetylated 2‐deoxy‐KDN ethyl ester 23 were consistent with those reported for the corresponding methyl ester derived from natural KDN. 相似文献
8.
A series of novel pyrazolyl‐substituted 1,3,4‐oxadiazole derivatives ( 4a‐4o ) were prepared by cyclization of the intermediate N′‐((3‐aryl‐l‐phenyl‐pyrazol‐4‐yl)methylene)arylhydrazide with acetic anhydride. The structures of the new compounds were confirmed by IR, 1H NMR, MS and elemental analysis. Furthermore, preliminary bioassay of some of the title compounds indicated that they exhibited moderate inhibition against HIV‐1 PR. 相似文献
9.
Anthony Linden C. Kuan Lee A. S. Muhammad Sofian 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(9):1098-1100
At 160 K, the glucopyranosyl ring of the title compound, C20H28ClIO13, has a near‐ideal 4C1 conformation and the fructofuranosyl ring has a twist 4T3 conformation. The two hydroxy groups are involved in intra‐ and intermolecular hydrogen bonds, with the latter interactions linking the molecules into infinite one‐dimensional chains. The absolute configuration of the molecule has been determined. 相似文献
10.
Mohammed Sydia Mohamed Said Ould Bahia Djerrari M'Barek El Abbassi Jilali Fifani El‐Mokhtar Essassi Brahim El‐Bali Michael Bolte 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(4):e165-e166
The title compound, C14H16N2O2, contains a diazepine ring, which appears in a boat conformation. An intramolecular hydrogen bond is formed between the NH group of the diazepine ring and a carbonyl O atom of one of the side chains. 相似文献
11.
Graeme J. Gainsford Cornelis Lensink Andrew Falshaw 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(11):o650-o652
The novel title compound, C25H31O6P, contains rigid fused rings which are shown to be similar to the precursor structures. Weak C—H⋯O intermolecular interactions produce two‐dimensional sheets composed of R44(28) rings. 相似文献
12.
Renate Gessmann Hans Brückner Kyriacos Petratos 《Acta Crystallographica. Section C, Structural Chemistry》2014,70(4):405-407
The title peptide, N‐benzyloxycarbonyl‐α‐aminoisobutyryl‐α‐aminoisobutyryl‐α‐aminoisobutyryl‐L‐alanine tert‐butyl ester or Z‐Aib‐Aib‐Aib‐L‐Ala‐OtBu (Aib is α‐aminoisobutyric acid, Z is benzyloxycarbonyl and OtBu indicates the tert‐butyl ester), C27H42N4O7, is a left‐handed helix with a right‐handed conformation in the fourth residue, which is the only chiral residue. There are two 4→1 intramolecular hydrogen bonds in the structure. In the lattice, molecules are hydrogen bonded to form columns along the c axis. 相似文献
13.
Urmila H. Patel Chaitanya G. Dave Mukesh M. Jotani Hetal C. Shah 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(3):o191-o192
The crystal structure of the title compound, C20H18N2O, reveals a distorted half‐chair conformation of the central tetrahydropyridine (THP) ring, with the cyano‐ and adjacent phenyl‐substituted C atoms displaced by 0.329 (1) and ?0.315 (1) Å, respectively, from the THP best plane. Steric interactions force the phenyl rings out of the THP plane by 49.21 (9) and 65.76 (5)°. The cyano moiety is coplanar with the THP plane. 相似文献
14.
Vladimir N. Nesterov Elena A. Viltchinskaia 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(5):616-618
The structures of the title compounds, C15H13N3O4, (I), and C16H15N3O5 [IUPAC name: ethyl 6‐amino‐5‐cyano‐2‐methyl‐4‐(3‐nitrophenyl)‐4H‐pyrano‐3‐carboxylate], (II), are very similar, with the heterocyclic rings adopting boat conformations. The pseudo‐axial m‐nitrophenyl substituents are rotated by 84.0 (1) and 98.7 (1)° in (I) and (II), respectively, with respect to the four coplanar atoms of the boat. The dihedral angles between the phenyl rings and nitro groups are 12.1 (2) and 8.4 (2)° in (I) and (II), respectively. The two compounds have similar patterns of intermolecular N—H?O and N—H?N hydrogen bonding, which link molecules into infinite tapes along b . 相似文献
15.
Andreas Fischer Daniel Stern Andrea Thorn Sascha Abraham Dietmar Stalke Uwe Klingebiel Prof. Dr. 《无机化学与普通化学杂志》2010,636(8):1527-1532
The lithium salt (HC–NCMe3)2SiFNLiR ( 1 ) R = C6H3(2,6‐CHMe2)2 reacts with trichlorogallium under displacement of the lithium ion by GaCl3 to give the adduct [(HC–NCMe3)2SiFN]– [(GaCl3)R·Li(thf)4]+ ( 1 ). Compound 1 thermally loses LiCl and forms the bicyclic ring intermediates V and VI . Compound VI adds the aniline H2NC6H3(2,6‐CHMe2)2 and the unsaturated, seven‐membered ring compound –NCMe3–CH2–CH=NCMe3GaCl2–NR–SiFNHR– ( 2 ) is obtained. The addition is accompanied by an enamine‐imine‐tautomerism and proves the Lewis acid character of the silicon atom in an unknown 3‐center‐2‐electron interaction of one nitrogen atom with the silicon and gallium atoms. Quantum chemical calculations of the thermal isomerisation process and crystal structures of 1 and 2 are reported. 相似文献
16.
17.
L. Vijayalakshmi V. Parthasarathi Vipul Vora Bhavik Desai Anamik Shah 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(7):817-818
In the title salt, C5H12N+·C29H23O6?, both benzopyran systems are planar. Intermolecular N—H?O hydrogen bonds and a short O—H?O intramolecular hydrogen bond are observed in the structure. 相似文献
18.
John N. Low Justo Cobo Manuel Nogueras Adolfo Snchez Jairo Quiroga Carlos Cisneros 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(1):o38-o39
The supramolecular structure of the title compound, C18H17ClN2O2, is determined by the intersection of two chains formed by N—H⋯O and N—H⋯N hydrogen bonds, forming a two‐dimensional sheet. 相似文献
19.
Rafael Germano Santana Derisvaldo Rosa Paiva Roberto da Silva Gomes Adriana Karla C. A. Reis 《Magnetic resonance in chemistry : MRC》2013,51(5):316-319
The complete assignment of the 1H and 13C NMR spectra of various 2‐acetamido‐3‐mercapto‐3‐methyl‐N‐aryl‐butanamides and 2‐acetamide‐3‐methyl‐3‐nitrososulfanyl‐N‐aryl‐butanamides with p‐methoxy, o‐chloro and m‐chloro substituents is reported. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
20.
Jana Sopkov‐de Oliveira Santos Anna Caruso Jean‐Franois Lohier Jean‐Charles Lancelot Sylvain Rault 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(8):o453-o455
The title carbazolyl boronic ester, C22H28BNO2, (I), is a building block for the synthesis of new carbazole derivatives of potential utility as pharmaceutically active compounds. The crystal structure of (I) and of the title bromocarbazole compound, C16H16BrN, (II), the synthetic precursor of (I), were solved and analysed with the aim of understanding the lack of reactivity of (I) under Suzuki cross‐coupling reaction conditions. In both structures, the methyl groups are coplanar with the carbazole ring system, and the ethyl group lies out of the carbazole plane. The dioxaborolane ring of boronic ester (I) adopts a half‐chair conformation but lies approximately in a planar orientation with respect of the carbazole ring system, whereas the Br atom of (II) is coplanar with the carbazole plane. In (I), the carbazole–boronic ester C—B bond length is 1.5435 (14) Å, which is somewhat shorter than the usual value of 1.57 Å. 相似文献