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1.
Jií Ludvík Jií Urban Jan Fbry Ivana Císaov 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(4):o259-o262
The title structures, both C10H10N4O, are substitutional isomers. The N—N bond lengths are longer and the C=N bond lengths are shorter by ca 0.025 Å than the respective average values in the C=N—N=C group of asymmetric triazines; the assessed respective bond orders are 1.3 and 1.7. There are N—H⋯O and N—H⋯N hydrogen bonds in both structures, with 4‐amino‐3‐methyl‐6‐phenyl‐1,2,4‐triazin‐5(4H)‐one containing a rare bifurcated N—H⋯N,N hydrogen bond. The structures differ in their molecular stacking and the hydrogen‐bonding patterns. 相似文献
2.
Andrzej Gzella Maria D. Rozwadowska 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(8):981-982
The absolute configuration of the title compound, alternatively called (+)‐(4,5‐dihydro‐2,5‐diphenyloxazol‐4‐yl)methanol, C16H15NO2, has been confirmed as 4S,5S. The hydroxymethyl group and phenyl ring at the asymmetric C atoms exhibit β and α orientations, respectively. The exocyclic C—C bonds at the asymmetric C atoms are mutually anticlinal (?ac). The hydroxyl group and the N atom of the oxazoline ring are involved in an intermolecular hydrogen bond leading to chains of molecules. 相似文献
3.
Synthesis of Analogues of Indole Alkaloids from Sea Sponges – Aplysinopsins by the Reaction of Amines with (4Z)‐4‐[(1H‐indol‐3‐yl)‐methylene]‐1,3‐oxazol‐5(4H)‐ones 下载免费PDF全文
A new two‐step approach toward the synthesis of aplysinopsin analogues 5‐(1‐R‐1H‐indol‐3‐ylmethylene)‐2‐aryl‐3,5‐dihydroimidazol‐4‐ones consisting in obtaining and reaction of 4‐(1‐R‐1H‐indol‐3‐ylmethilene)‐2‐Ar‐4H‐oxazol‐5‐ones with amines was developed. The configuration of starting compounds and final products was determined by 13С and 1H‐nmr spectroscopy. 相似文献
4.
Catalytic Asymmetric Michael Reaction of 5H‐Oxazol‐4‐Ones with α,β‐Unsaturated Acyl Imidazoles 下载免费PDF全文
Bangzhi Zhang Fengxia Han Linqing Wang Dan Li Dongxu Yang Xiaoli Yang Junxian Yang Xiaofang Li Dr. Depeng Zhao Prof. Dr. Rui Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(48):17234-17238
The asymmetric Michael reaction between 5H‐oxazol‐4‐ones and α,β‐unsaturated acyl imidazoles is reported. A novel 2‐benzo[b]thiophenyl‐modified chiral ProPhenol species is synthesized and used as a ligand, leading to good enantioselectivities in this asymmetric conjugate addition reaction. Furthermore, the introduction of phenol additives as achiral co‐ligands is found to improve the reaction’s chemical yields, diastereoselectivities, and enantioselectivities. 相似文献
5.
Vratislav Langer Miroslav Ko Dalma Gyepesov Juraj Kronek Jozef Lusto Mariana Sldkovi
ov 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(10):o602-o606
Crystal structures are reported for three isomeric compounds, namely 2‐(2‐hydroxyphenyl)‐2‐oxazoline, (I), 2‐(3‐hydroxyphenyl)‐2‐oxazoline, (II), and 2‐(4‐hydroxyphenyl)‐2‐oxazoline, (III), all C9H9NO2 [systematic names: 2‐(4,5‐dihydro‐1,3‐oxazol‐2‐yl)phenol, (I), 3‐(4,5‐dihydro‐1,3‐oxazol‐2‐yl)phenol, (II), and 4‐(4,5‐dihydro‐1,3‐oxazol‐2‐yl)phenol, (III)]. In these compounds, the deviation from coplanarity of the oxazoline and benzene rings is dependent on the position of the hydroxy group on the benzene ring. The coplanar arrangement in (I) is stabilized by a strong intramolecular O—H⋯N hydrogen bond. Surprisingly, the 2‐oxazoline ring in molecule B of (II) adopts a 3T4 (C2TC3) conformation, while the 2‐oxazoline ring in molecule A, as well as that in (I) and (III), is nearly planar, as expected. Tetramers of molecules of (II) are formed and they are bound together via weak C—H⋯N hydrogen bonds. In (III), strong intermolecular O—H⋯N hydrogen bonds and weak intramolecular C—H⋯O hydrogen bonds lead to the formation of an infinite chain of molecules perpendicular to the b direction. This paper also reports a theoretical investigation of hydrogen bonds, based on density functional theory (DFT) employing periodic boundary conditions. 相似文献
6.
Ricaurte Rodríguez Justo Cobo Manuel Nogueras John N. Low Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(12):o697-o700
The molecular dimensions of both 2‐amino‐6‐(N‐methylanilino)pyrimidin‐4(3H)‐one, C11H12N4O, (I), and 2‐amino‐6‐(N‐methylanilino)‐5‐nitropyrimidin‐4(3H)‐one, C11H11N5O3, (II), are consistent with considerable polarization of the molecular–electronic structures. The molecules of (I) are linked into a three‐dimensional framework by a combination of one N—H...N hydrogen bond, two independent N—H...O hydrogen bonds and one C—H...π(arene) hydrogen bond. The molecules of (II) are linked into ribbons containing three types of edge‐fused ring by the combination of two independent three‐centre N—H...(O)2 hydrogen bonds. 相似文献
7.
A palladium‐catalyzed intramolecular α‐arylation of an amide in the presence of a bulky chiral N‐heterocyclic carbene ligand is the key step in the first catalytic synthesis of (3R)‐6‐chloro‐3‐(3‐chlorobenzyl)‐1,3‐dihydro‐3‐(3‐methoxyphenyl)‐2H‐indol‐2‐one ((R)‐ 5 ). This oxindole, in racemic form, had been shown previously to be an anticancer agent. (R)‐ 5 was obtained with an overall yield of 45% and with 96% enantioselectivity. 相似文献
8.
Jessica Orrego Hernandez Jaime Portilla Justo Cobo Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2015,71(5):363-368
Cyclohexylamine reacts with 5‐chloro‐3‐methyl‐1‐(pyridin‐2‐yl)‐1H‐pyrazole‐4‐carbaldehyde to give 5‐cyclohexylamino‐3‐methyl‐1‐(pyridin‐2‐yl)‐1H‐pyrazole‐4‐carbaldehyde, C16H20N4O, (I), formed by nucleophilic substitution, but with 5‐chloro‐3‐methyl‐1‐phenyl‐1H‐pyrazole‐4‐carbaldehyde the product is (Z)‐4‐[(cyclohexylamino)methylidene]‐3‐methyl‐1‐phenyl‐1H‐pyrazol‐5(4H)‐one, C17H21N3O, (II), formed by condensation followed by hydrolysis. Compound (II) crystallizes with Z′ = 2, and in one of the two independent molecular types the cyclohexylamine unit is disordered over two sets of atomic sites having occupancies of 0.65 (3) and 0.35 (3). The vinylogous amide portion in each compound shows evidence of electronic polarization, such that in each the O atom carries a partial negative charge and the N atom of the cyclohexylamine portion carries a partial positive charge. The molecules of (I) contain an intramolecular N—H...N hydrogen bond, and they are linked by C—H...O hydrogen bonds to form sheets. Each of the two independent molecules of (II) contains an intramolecular N—H...O hydrogen bond and each molecular type forms a centrosymmetric dimer containing one R22(4) ring and two inversion‐related S(6) rings. 相似文献
9.
Kritof Kranjc Marijan Ko
evar Franc Perdih 《Acta Crystallographica. Section C, Structural Chemistry》2011,67(6):o201-o205
Methyl 2‐benzamido‐4‐(3,4‐dimethoxyphenyl)‐5‐methylbenzoate, C24H23NO5, (Ia), and N‐{5‐benzoyl‐2‐[(Z)‐2‐methoxyethenyl]‐4‐methylphenyl}benzamide, C24H21NO3, (IIa), were formed via a Diels–Alder reaction of appropriately substituted 2H‐pyran‐2‐ones and methyl propiolate or (Z)‐1‐methoxybut‐1‐en‐3‐yne, respectively. Each of these cycloadditions might yield two different regioisomers, but just one was obtained in each case. In (Ia), an intramolecular N—H...O hydrogen bond closes a six‐membered ring. A chain is formed due to aromatic π–π interactions, and a three‐dimensional framework structure is formed by a combination of C—H...O and C—H...π(arene) hydrogen bonds. Compound (IIa) was formed not only regioselectively but also chemoselectively, with just the triple bond reacting and the double bond remaining unchanged. Compound (IIa) crystallizes as N—H...O hydrogen‐bonded dimers stabilized by aromatic π–π interactions. Dimers of (IIa) are connected into a chain by weak C—H...π(arene) interactions. 相似文献
10.
Dina Boyarskaya Margarita Avdontceva Tatiana Chulkova 《Acta Crystallographica. Section C, Structural Chemistry》2015,71(2):155-158
Acidic hydrogen containing 2‐isocyano‐4‐methylphenyl diphenylacetate, C22H17NO2, (I), was synthesized by the base‐promoted reaction between 5‐methylbenzoxazole and diphenylacetyl chloride. Achiral (I) crystallizes in the chiral P212121 space group. The C[triple‐bond]N bond length is 1.164 (2) Å and the angle between the OCO and 2‐isocyano‐4‐methylphenyl planes is 69.10 (16)°. Molecules are linked via C=O...Hphenyl and bifurcated N[triple‐bond]C...Hphenyl/N[triple‐bond]C...Hmethine hydrogen bonds, forming one‐dimensional arrays. 相似文献
11.
Viktor Kettmann Jan Svtlík 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(8):o419-o421
The reaction between 4‐(4‐methylphenyl)but‐3‐en‐2‐one and aminoguanidine produced an unexpected product of formula C12H15N3O, consisting of a carboxamide moiety joined to a substituted pyrazoline ring at one of the N atoms. The pyrazoline ring adopts a flat‐envelope conformation and the substituted phenyl ring is oriented almost perpendicular to the heterocycle. The carbonyl O atom has partial anionic character as a result of the transfer of π density from the two adjacent sp2 N atoms and is involved in an intermolecular hydrogen bond with the amide group. 相似文献
12.
Hong‐Cheng Shen Yu‐Feng Wu Ying Zhang Lian‐Feng Fan Prof. Dr. Zhi‐Yong Han Prof. Dr. Liu‐Zhu Gong 《Angewandte Chemie (International ed. in English)》2018,57(9):2372-2376
A PdII‐catalyzed asymmetric aminohydroxylation of 1,3‐dienes with N‐tosyl‐2‐aminophenols was developed by making use of a chiral pyridinebis(oxazoline) ligand. The highly regioselective reaction provides direct and efficient access to chiral 3,4‐dihydro‐2H‐1,4‐benzoxazines in high yield and enantioselectivity (up to 96:4 e.r.). The reaction employs readily available N‐tosyl‐2‐aminophenols as a unique aminohydroxylation reagent and is complementary to known asymmetric aminohydroxylation methods. 相似文献
13.
Christopher Glidewell John N. Low Manuel Melguizo Antonio Quesada 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(1):o14-o18
In 2‐amino‐4,6‐dimethoxy‐5‐nitropyrimidine, C6H8N4O4, the molecules are linked by one N—H⋯N and one N—H⋯O hydrogen bond to form sheets built from alternating R(8) and R(32) rings. In isomeric 4‐amino‐2,6‐dimethoxy‐5‐nitropyrimidine, C6H8N4O4, which crystallizes with Z′ = 2 in P, the two independent molecules are linked into a dimer by two independent N—H⋯N hydrogen bonds. These dimers are linked into sheets by a combination of two‐centre C—H⋯O and three‐centre C—H⋯(O)2 hydrogen bonds, and the sheets are further linked by two independent aromatic π–π‐stacking interactions to form a three‐dimensional structure. 相似文献
14.
The synthesis of α‐benzamido‐α‐benzyl lactones 23 of various ring size was achieved either via ‘direct amide cyclization’ by treatment of 2‐benzamido‐2‐benzyl‐ω‐hydroxy‐N,N‐dimethylalkanamides 21 in toluene at 90 – 110° with HCl gas or by ‘ring transformation’ of 4‐benzyl‐4‐(ω‐hydroxyalkyl)‐2‐phenyl‐1,3‐oxazol‐5(4H)‐ones under the same conditions. The precursors were obtained by C‐alkylations of 4‐benzyl‐2‐phenyl‐1,3‐oxazol‐5(4H)‐one ( 15 ) with THP‐ or TBDMS‐protected ω‐hydroxyalkyl iodides. Ring opening of the THP‐protected oxazolones by treatment with Me2NH followed by deprotection of the OH group gave the diamides 21 , whereas deprotection of the TBDMS series of oxazolones 25 with TBAF followed by treatment with HCl gas led to the corresponding lactones 23 in a one‐pot reaction. 相似文献
15.
Kate J. Akerman Orde Q. Munro 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(3):258-262
The Schiff base enaminones (3Z)‐4‐(5‐ethylsulfonyl‐2‐hydroxyanilino)pent‐3‐en‐2‐one, C13H17NO4S, (I), and (3Z)‐4‐(5‐tert‐butyl‐2‐hydroxyanilino)pent‐3‐en‐2‐one, C15H21NO2, (II), were studied by X‐ray crystallography and density functional theory (DFT). Although the keto tautomer of these compounds is dominant, the O=C—C=C—N bond lengths are consistent with some electron delocalization and partial enol character. Both (I) and (II) are nonplanar, with the amino–phenol group canted relative to the rest of the molecule; the twist about the N(enamine)—C(aryl) bond leads to dihedral angles of 40.5 (2) and −116.7 (1)° for (I) and (II), respectively. Compound (I) has a bifurcated intramolecular hydrogen bond between the N—H group and the flanking carbonyl and hydroxy O atoms, as well as an intermolecular hydrogen bond, leading to an infinite one‐dimensional hydrogen‐bonded chain. Compound (II) has one intramolecular hydrogen bond and one intermolecular C=O...H—O hydrogen bond, and consequently also forms a one‐dimensional hydrogen‐bonded chain. The DFT‐calculated structures [in vacuo, B3LYP/6‐311G(d,p) level] for the keto tautomers compare favourably with the X‐ray crystal structures of (I) and (II), confirming the dominance of the keto tautomer. The simulations indicate that the keto tautomers are 20.55 and 18.86 kJ mol−1 lower in energy than the enol tautomers for (I) and (II), respectively. 相似文献
16.
Frank Seela Ping Ding Xiaohua Peng Henning Eickmeier Hans Reuter 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(10):o600-o602
The title compound, 2,4‐diamino‐5‐bromo‐7‐(2‐deoxy‐2‐fluoro‐β‐d ‐arabinofuranosyl)‐7H‐pyrrolo[2,3‐d]pyrimidine, C11H13BrFN5O3, shows two conformations of the exocyclic C4′—C5′ bond, with the torsion angle γ (O5′—C5′—C4′—C3′) being 170.1 (3)° for conformer 1 (occupancy 0.69) and 60.7 (7)° for conformer 2 (occupancy 0.31). The N‐glycosylic bond exhibits an anti conformation, with χ = −114.8 (4)°. The sugar pucker is N‐type (C3′‐endo; 3T4), with P = 23.3 (4)° and τm = 36.5 (2)°. The compound forms a three‐dimensional network that is stabilized by several intermolecular hydrogen bonds (N—H...O, O—H...N and N—H...Br). 相似文献
17.
Marco Crisma Fernando Formaggio Claudio Toniolo 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(6):695-696
Benzyl N‐[8‐(4,4‐dimethyl‐5‐oxo‐4,5‐dihydrooxazol‐2‐yl)‐2,5,5,8‐tetramethyl‐3,6‐dioxo‐4,7‐diazanon‐2‐yl]carbamate, C24H34N4O6, an oxazol‐5(4H)‐one from N‐α‐benzyloxycarbonyl‐(Aib)4‐OH (Aib = α‐aminoisobutyryl) represents the longest peptide oxazolone so far characterized by X‐ray diffraction. The overall geometry of the oxazolone ring compares well with literature data. The Aib(1) and Aib(2) residues are folded into a type III β‐bend, while the conformation adopted by Aib(3), preceding the oxazolone moiety, is semi‐extended. The disposition of the oxazolone ring relative to the preceding residue is stabilized by C—H?N and C—H?O intramolecular interactions. 相似文献
18.
Xiaohua Peng Hans Reuter Henning Eickmeier Frank Seela 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(10):o593-o595
In 4‐chloro‐7‐(2‐deoxy‐β‐d ‐erythro‐pentofuranosyl)‐7H‐pyrrolo[2,3‐d]pyrimidine‐2,4‐diamine, C11H14ClN5O3, the conformation of the N‐glycosylic bond is between anti and high‐anti [χ = −102.5 (6)°]. The 2′‐deoxyribofuranosyl unit adopts the C3′‐endo‐C4′‐exo (3T4) sugar pucker (N‐type) with P = 19.6° and τm = 32.9° [terminology: Saenger (1989). Landolt‐Börnstein New Series, Vol. 1, Nucleic Acids, Subvol. a, edited by O. Madelung, pp. 1–21. Berlin: Springer‐Verlag]. The orientation of the exocyclic C4′—C5′ bond is +ap (trans) with a torsion angle γ = 171.5 (4)°. The compound forms a three‐dimensional network that is stabilized by four intermolecular hydrogen bonds (N—H⋯O and O—H⋯N) and one intramolecular hydrogen bond (N—H⋯Cl). 相似文献
19.
Brønsted Acid Catalyzed,Conjugate Addition of β‐Dicarbonyls to In Situ Generated ortho‐Quinone Methides—Enantioselective Synthesis of 4‐Aryl‐4H‐Chromenes 下载免费PDF全文
M. Sc. Osama El‐Sepelgy M. Sc. Stefan Haseloff Dr. Santosh Kumar Alamsetti Prof. Dr. Christoph Schneider 《Angewandte Chemie (International ed. in English)》2014,53(30):7923-7927
We describe herein a catalytic, enantioselective process for the synthesis of 4H‐chromenes which are important structural elements of many natural products and biologically active compounds. A sequence comprising a conjugate addition of β‐diketones to in situ generated ortho‐quinone methides followed by a cyclodehydration reaction furnished 4‐aryl‐4H‐chromenes in generally excellent yields and high optical purity. A BINOL‐based chiral phosphoric acid was employed as a Brønsted acid catalyst which converted ortho‐hydroxy benzhydryl alcohols into hydrogen‐bonded ortho‐quinone methides and effected the carbon–carbon bond‐forming event with high enantioselectivity. 相似文献
20.
Akiko Hori Yasuhide Ishida Takahiro Kikuchi Kumiko Miyamoto Hiroshi Sakaguchi 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(12):o593-o597
In the crystal structure of 6‐phenyl‐3‐thioxo‐2,3,4,5‐tetrahydro‐1,2,4‐triazin‐5‐one, C9H7N3OS, (I), the 1,2,4‐triazine moieties are connected by face‐to‐face contacts through two kinds of double hydrogen bonds (N—H...O and N—H...S), which form planar ribbons along the a axis. The ribbons are crosslinked through C—H...π interactions between the phenyl rings. The molecular structures of two regioisomeric compounds, namely 6‐phenyl‐2,3‐dihydro‐7H‐1,3‐thiazolo[3,2‐b][1,2,4]triazin‐7‐one, C11H9N3OS, (II), and 3‐phenyl‐6,7‐dihydro‐4H‐1,3‐thiazolo[2,3‐c][1,2,4]triazin‐4‐one, C11H9N3OS, (III), which were prepared by the condensation reaction of (I) with 1,2‐dibromoethane, have been characterized by X‐ray crystallography and spectroscopic studies. The crystal structures of (II) and (III) both show two crystallographically independent molecules. While the two compounds are isomers, the unit‐cell parameters and crystal packing are quite different and (II) has a chiral crystal structure. 相似文献