The effect of hydrogen bonding on the conformations of 2‐(1H‐indol‐3‐yl)‐2‐oxoacetamide and 2‐(1H‐indol‐3‐yl)‐N,N‐dimethyl‐2‐oxoacetamide

In the title compounds, C₁₀H₈N₂O₂, (I), and C₁₂H₁₂N₂O₂, (II), the two carbonyl groups are oriented with torsion angles of −149.3 (3) and −88.55 (15)°, respectively. The single‐bond distances linking the two carbonyl groups are 1.528 (4) and 1.5298 (17) Å, respectively. In (I), the molecules are linked by an elaborate system of N—H...O hydrogen bonds, which form adjacent R²₂(8) and R⁴₂(8) ring motifs to generate a ladder‐like construct. Adjacent ladders are further linked by N—H...O hydrogen bonds to build a three‐dimensional network. The hydrogen bonding in (II) is far simpler, consisting of helical chains of N—H...O‐linked molecules that follow the 2₁ screw of the b axis. It is the presence of an elaborate hydrogen‐bonding system in the crystal structure of (I) that leads to the different torsion angle for the orientation of the two adjacent carbonyl groups from that in (II).     

Studies with enamines: Reactivity of N,N‐dimethyl‐N‐[(E)‐2‐(4‐nitrophenyl)‐1‐ethenyl]amine towards nitrilimine and aromatic diazonium salts

In the presence of triethylamine, cycloaddition reaction of enamine 1 with hydrazonoyl halides 2 followed by dimethylamine elimination was achieved, yielding the corresponding 1,3,4‐trisubstituted pyrazoles 4 . Coupling of enamine 1 with aromatic diazonium salts afforded 2‐(arylhydrazono)‐2‐(4‐nitrophenyl)acetaldehyde 9 in good yield. Refluxing the phenyl hydrazone 9a with chloroacetone in ethanol in the presence of triethylamine afforded 1,3,5‐trisubstituted pyrazole 12a , formed via intermediate 11a. Reaction of 9a with hydroxylamine hydrochloride in ethanol in the presence of anhydrous sodium acetate yielded oxime 13a which was irradiated in a microwave oven in the presence of acetic acid to afford a mixture of 15a and 16a.     

Diastereomers (RC,SP)‐ and (RC,RP)‐S‐methyl P‐(3‐azidopropyl)‐N‐[(1R)‐1‐phenylethyl]phosphonamidothioate

Diastereoisomers of the title organophosphorus compound, C₁₂H₁₉N₄OPS, denoted R_CS_P, (I), and R_CR_P, (II), were structurally characterized and compared. Asymmetric phosphorus compounds are of interest with regard to the use of these systems as possible protein probes via the stereoselective delivery of an azide group tethered to the P atom into key protein regions. The diastereomers were produced in a 1:1 mixture and isolated by chromatography. Although both isomers crystallize in the same space group with superficially similar cell constants, conformational and packing differences are pronounced. Despite the conformational differences, strong intermolecular hydrogen bonding links both isomers into chains parallel to the a axis [N...O = 2.8609 (18) and 2.966 (3) Å in (I) and (II), respectively], with C—H...π interchain interactions of ca 3.5 Å.     

Crystallographic report: [N,N′‐Bis‐(6‐methylpyrid‐2‐ylium)‐(1R,2R)‐1,2‐diaminocyclohexane] bis‐[(p‐cymene)‐ trichlororuthenate(II)]

The chiral compound (H₂cydiampy)[RuCl₃(p‐cymene)]₂ has been obtained in high yield by treating [RuCl₂(p‐cymene)]₂ with an excess of hydrochloric acid in the presence of one equivalent of N,N′‐bis‐(6‐methylpyrid‐2‐yl)‐(1R,2R)‐1,2‐diaminocyclohexane (cydiampy). It crystallizes in the chiral tetragonal space group P4₃2₁2, with half of the atoms of the dication related to the other half by a crystallographic C₂ axis that also makes equivalent the two anionic metal moieties. Copyright © 2005 John Wiley & Sons, Ltd.     

N,N′‐Butane‐1,4‐diylbis­(bromo­acetamide)

The title compound, C₈H₁₄Br₂N₂O₂, lies about an inversion centre and adopts a pleated conformation, with the C(O)—NH—CH₂—CH₂ and NH—CH₂—CH₂—CH₂ torsion angles of the butane­diamine residue being −89.5 (6) and −62.1 (7)°, respectively. These data are useful in discerning the structure of polymers containing such a unit. A skew conformation is found for the Br—CH₂—C(O)—NH torsion angle [−124.2 (4)°]. The mol­ecular packing is stabilized by strong hydrogen bonds between amide groups and also by weak CH₂⋯OC inter­actions. In this way, each mol­ecule inter­acts with its six closest neighbours through eight hydrogen bonds.     

The twinned crystal structure of rac‐(R,R)‐N,N′‐oxalyl­divalinol

The title compound, rac‐(R,R)‐N,N′‐bis(1‐hydroxy‐3‐methyl‐2‐butyl)oxalamide, C₁₂H₂₄N₂O₄, crystallizes as a non‐merohedral twin in the triclinic space group . The twin is generated by a twofold rotation about c*. The terminal hydroxy groups of molecules related by an inversion center form hydrogen‐bonded dimers. This hydrogen‐bonding pattern is further extended into a one‐dimensional chain by N—H⋯O hydrogen bonds.     

N‐[(R)‐1‐(2‐Hydr­oxy‐5‐methyl­phen­yl)­eth­yl]‐N‐[(R)‐1‐(2‐meth­oxy‐5‐methyl­phen­yl)‐2‐phenyl­eth­yl]aminium chloride

The title compound, C₂₅H₃₀NO₂⁺·Cl⁻, has been synthesized, and the crystal structure shows that it is mainly stabilized through inter­molecular N—H·Cl and O—H·Cl and intra­molecular N—H·O hydrogen bonds. The absolute configuration of the new stereogenic center (the C atom adjacent to the N atom on the phenol side) was determined to have an R configuration.     

First Total Synthesis of N‐(3‐Guanidinopropyl)‐2‐(4‐hydroxyphenyl)‐2‐oxoacetamide

The first total synthesis of the α‐oxo amide‐based natural product, N‐(3‐guanidinopropyl)‐2‐(4‐hydroxyphenyl)‐2‐oxoacetamide ( 3 ), isolated from aqueous extracts of hydroid Campanularia sp., has been achieved. The α‐oxo amide 12 , prepared via the oxidative amidation of 1‐[4‐(benzyloxy)phenyl]‐2,2‐dibromoethanone ( 9a ) with 4‐{[(tert‐butyl)(dimethyl)silyl]oxy}butan‐1‐amine ( 10a ), has been used as the key intermediate in the total synthesis of 3 as HBr salt. On the way, an expeditious total synthesis of polyandrocarpamide C ( 2c ), isolated from marine ascidian Polyandrocarpa sp., was carried out in four steps.     

Crystallographic report: Bis[N,N‐dimethyl‐N′‐(pyrid‐2‐ylmethyl)‐ethylenediamine]zinc(II) diperchlorate

The zinc(II) atom in the centrosymmetric complex is in a distorted N₆ octahedral geometry defined by two tridentate ligands. Copyright © 2004 John Wiley & Sons, Ltd.     

Bis­[(R)‐3,5‐di­chloro‐N‐(1‐phenyl­ethyl)­salicyl­idene­aminato‐κ2N,O]­copper(II) and bis­[(R)‐3‐ethoxy‐N‐(1‐phenyl­ethyl)­salicyl­idene­aminato‐κ2N,O]copper(II)

The title compounds, [Cu(C₁₅H₁₂Cl₂NO)₂], (I), and [Cu(C₁₇­H₁₈NO₂)₂], (II), both adopt a compressed tetrahedral trans‐[CuN₂O₂] coordination geometry, the mol­ecules having an umbrella conformation overall. These complexes differ from one another with respect to the 1‐phenyl­ethyl­amine moieties, the direction of the benzene rings being either inside [in (I)] or inside and outside [in (II)] of the mol­ecules. The crystals of (I) and (II) have Δ(R,R) and Λ(R,R) absolute configurations, respectively.     

1‐[2‐(2,6‐Diisopropylanilino)‐1‐naphthyl]isoquinoline

The molecule of the title compound, C₃₁H₃₀N₂, contains a single intramolecular hydrogen bond, in contrast with the related N‐methyl compound which exists as hydrogen‐bonded dimers in the solid state [Cortright, Huffman, Yoder, Coalter & Johnston (2004). Organometallics, 23 , 2238–2250]. Application of the density functional theory programs CASTEP and DMol³ allows accurate assignment of the location of the H atoms in the structure.     

1‐[(4‐Chloro­benzoyl)­methyl]‐4‐(N,N‐di­methyl­amino)­pyridinium bromide sesquihydrate and 1‐[(4‐bromo­benzoyl)­methyl]‐4‐(N,N‐di­methyl­amino)­pyridinium bromide sesquihydrate

The title compounds, C₁₅H₁₆ClN₂O⁺·Br⁻·1.5H₂O and C₁₅H₁₆BrN₂O⁺·Br⁻·1.5H₂O, are isomorphous. The benzene ring is oriented nearly normal to the pyridine ring in both compounds. The molecular packing is mainly influenced by intermolecular O—H⋯O and O—H⋯Br interactions, as well as weak intramolecular C—H⋯O interactions. The H₂OBr⁻ units form an extended water–bromide chain, with a bridging water mol­ecule on a twofold axis.     

N‐[1‐(Penta­fluoro­phenyl)­ethyl]­acetamide

The title compound, C₁₀H₈F₅NO, crystallizes as a racemate with four symmetry‐independent mol­ecules in the asymmetric unit. The four mol­ecules form two hydrogen‐bonded pairs. Each pair is a building unit of an independent C(4) chain propagating parallel to the ab plane.     

Dichloro­[(6R,7S,8S,14S)‐(–)‐sparteine‐κ2N,N′]mercury(II)

In the title compound, [HgCl₂(C₁₅H₂₆N₂)], the chiral alkaloid (6R,7S,8S,14S)‐(−)‐l ‐sparteine acts as a bident­ate ligand, with two Cl⁻ ligands occupying the remaining coordination sites, producing a distorted tetra­hedron. The N—Hg—N plane is twisted by 81.1 (2)° from the Cl—Hg—Cl plane. The mid‐point of the N⋯N line does not lie exactly on the Cl—Hg—Cl plane but is tilted towards one of the N atoms by 0.346 Å. Similarly, the mid‐point of the Cl⋯Cl line is tilted toward one of the Cl atoms by 0.163 Å. The packing structure shows that the complex is stabilized by two inter­atomic Cl⋯H contacts involving both Cl atoms and the methyl­ene or methine H atoms of the (−)‐sparteine ligand.     

The diastereoisomers 2‐[(S/R)‐2‐chloro‐3‐quinolyl]‐2‐[(R)‐1‐(4‐methoxyphenyl)ethylamino]acetonitrile at 100 K

In the structures of the two enantiopure diastereoisomers of the title compound, C₂₀H₁₈ClN₃O, which crystallize in different space groups, the molecules are very similar as far as bond distances and angles are concerned, but more substantial differences are observed in some torsion angles. The crystal structures of both molecules can be described as zigzag layers along the c axis. The packing is stabilized by hydrogen‐bond interactions of N—H...O, C—H...Cl and C—H...π types for 2‐[(R)‐2‐chloro‐3‐quinolyl]‐2‐[(R)‐1‐(4‐methoxyphenyl)ethylamino]acetonitrile, and of N—H...N, C—H...O and C—H...π types for 2‐[(S)‐2‐chloro‐3‐quinolyl]‐2‐[(R)‐1‐(4‐methoxyphenyl)ethylamino]acetonitrile, resulting in the formation of two‐ and three‐dimensional networks.     

Polymerization of conjugated 5‐[(5‐ethynyl‐1‐naphthyl)ethynyl]‐N,N‐dimethylnaphthalen‐1‐amine with rhodium and palladium complexes

The monomer 5‐[(5‐ethynyl‐1‐naphthyl)ethynyl]‐N,N‐dimethylnaphthalen‐1‐amine was satisfactory obtained through the heterocoupling reaction of 5‐ethynyl‐N,N‐dimethylnaphthalen‐1‐amine and 4‐(5‐iodo‐1‐naphthyl)‐2‐methyl‐3‐butyn‐2‐ol catalyzed by a palladium–copper system, followed by acetone elimination. Poly{5‐[(5‐ethynyl‐1‐naphthyl)ethynyl]‐N,N‐dimethylnaphthalen‐1‐amine} was obtained through the reaction of the acetylene monomer with homogeneous rhodium and palladium catalyst complexes. The structure of the polymers always showed a trans–cisoidal chain configuration on the basis of IR and NMR spectra. Moreover, only for the rhodium catalyst complex in methanol was a dimeric product isolated in a very low yield, having a conjugated terminal ene–yne structure, which permitted the consideration of a metallated chain‐transfer intermediate in the polymer propagation. The mass determination of the polymers, by osmometry and gel permeation chromatography techniques, showed low average molecular weights. The kinetics of the catalyzed polymerization were analyzed. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2038–2047, 2007     

2‐(N,N‐Diphenylamino)benzoic acid

Shaped like a distorted propeller, mol­ecules of the title compound, C₁₉H₁₅NO₂, form centrosymmetric dimers in the crystalline phase in which the carboxy groups are linked through two hydrogen bonds. These dimers are arranged in columns held together via dispersive interactions between the phenyl moieties. The N atom and the three surrounding C atoms lie almost in the same plane, which implies that the lone electron pair of the N atom is involved in conjugation with the π systems of the phenyl fragments.     

3‐[(2‐Oxo‐1‐naphthylidene)methyl­amino]­benzoic acid

The title compound, C₁₈H₁₃NO₃, exists as a keto­amino tautomer implying a fairly short N—H?O intramolecular hydrogen bond between the 2‐naphthalenone and amino moieties [N?O 2.531 (3) Å] which is enhanced by the π‐electron delocalization effect. The naphthald­imine and 3‐carboxy­phenyl fragments are inclined at an angle of 4.41 (7)°, so the mol­ecule is almost planar. The mol­ecules are connected by intermolecular O—H?O hydrogen bonds between the carboxy and keto O atoms, forming infinite chains around the twofold screw axes parallel to b .     

N‐[(Diphenoxyphosphoryl)oxy]‐2‐phenyl‐1H‐benzimidazole as a versatile reagent for synthesis O‐alkylhydroxamic acids

Highly efficient reagent, N‐[(diphenoxyphosphoryl)oxy]‐2‐phenyl‐1H‐benzimidazole was synthesized and its applicability was demonstrated for the synthesis of O‐alkyl hydroxamic acids. The efficiency of the reagent was evaluated through the synthesis of range of O‐alkyl hydroxamic acids from aromatic carboxylic acids as well as N‐protected amino acids. The enatiomeric purity of synthesized compounds was measured using chiral HPLC and the degree of racemization that occurred was found to be negligible.     

Crystallographic report: Dicyclohexyltin N‐[(E)‐(5‐chloro‐2‐hydroxyphenyl) methylene]‐(L)‐isoleucinate

The tin atom in the title compound is in a distorted trigonal bipyramidal geometry and forms a five‐ and six‐membered chelate rings with the tridentate ligand. Copyright © 2004 John Wiley & Sons, Ltd.