M.V.N. de Souza

2-Bromo­pyridine-3-carboxylic acid

The carboxylic acid residue in the title compound, C6H4BrNO2, is twisted out of the plane of the other atoms, as indicated by the (Br)C—C—C—Ocarbonyl torsion angle of −20.1 (9)°. In the crystal, supramolecular chains mediated by O—H⋯N hydrogen bonds are formed with base vector [201] and C—H⋯O interactions reinforce the packing.

7-Chloro-4-[(E)-2-(2-methoxy­benzyl­idene)hydrazin-1-yl]quinoline monohydrate

In the title hydrate, C17H14ClN3O·H2O, the dihedral angle between the quinoline fused-ring system and the benzene ring is 13.4 (2)° and the conformation about the C=N bond is E. In the crystal, Nh—H⋯Ow and Ow—H⋯Nq (h = hydrozone, w = water and q = quinoline) hydrogen bonds generate a two-dimenstional network in the ac plane. A weak C—H⋯O interaction helps to consolidate the packing.

N-(4-Bromo­phen­yl)-2-(2-thien­yl)acetamide

The thienyl ring in the title compound, C12H10BrNOS, is disordered over two diagonally opposite positions, the major component having a site-occupancy factor of 0.660 (5). The molecule is twisted as evidenced by the dihedral angles of 70.0 (4) and 70.5 (6)° formed between the benzene ring and the two orientations of the disordered thiophene ring. Linear supramolecular chains along the a axis are found in the crystal structure through the agency of N—H⋯O hydrogen bonding.

Three isomeric 1-(2-chloronicotinoyl)-2-(nitro­phenyl)hydrazines, including three polymorphs of 1-(2-chloronicotinoyl)-2-(2-nitrophenyl)hydrazine: hydrogen-bonded supramolecular structures in two and three dimensions

1-(2-Chloronicotinoyl)-2-(2-nitrophenyl)hydrazine, C12H9ClN4O3, crystallizes in three polymorphic forms, two monoclinic forms in space groups Cc (Ia) and P2(1) (Ib), and an orthorhombic form in space group Pbcn (Ic). In the Cc polymorph (Ia) the molecules are linked into sheets by combinations of one N-H...O and two C-H...O hydrogen bonds, while in the P2(1) polymorph (Ib) the molecules are linked into sheets by combinations of three hydrogen bonds, one each of N-H...O, C-H...N and C-H...O types. In the orthorhombic polymorph (Ic) the molecules are linked into a complex three-dimensional framework structure by a combination of one N-H...O, one N-H...N and three C-H...O hydrogen bonds, and an aromatic pi...pi stacking interaction. In the isomeric compound 1-(2-chloronicotinoyl)-2-(3-nitrophenyl)hydrazine (II) the molecules are again linked into a three-dimensional framework, this time by a combination of three hydrogen bonds, one each of N-H...O, N-H...N and C-H...O types, weakly augmented by a pi...pi stacking interaction. The molecules of 1-(2-chloronicotinoyl)-2-(4-nitrophenyl)hydrazine (III) are linked into sheets by a combination of three hydrogen bonds, one each of N-H...O, N-H...N and C-H...O types.

3-[(E)-(7-Chloro-4-quinol-yl)hydrazono-meth-yl]benzonitrile monohydrate.

The title monohydrate, C17H11ClN4·H2O, features an essentially planar organic molecule, as seen in the dihedral angle of 2.42 (8)° formed between the quinoline and benzene planes. The conformation about the imine bond is E, and the N—H group is oriented towards the quinoline residue. The major feature of the crystal packing is the formation of supramolecular chains along [100], whereby the water molecule accepts one N—H⋯O hydrogen bond and makes two O—H⋯N hydrogen bonds. A C—H⋯O link is also present.

Simple Methodology for the Preparation of Amino Alcohols from Amino Acid Esters Using NaBH4–Methanol in THF

Abstract Amino alcohols constitute a very useful and versatile class of organic compounds, with important applications in synthetic and medicinal chemistry. However, in most of the procedures described in the literature for the obtainment of these compounds, considerable limitations can be found, such as drastic conditions, long time reactions, poor yields, and purification problems. The present article describes a methodology that gives amino alcohols and N-protected amino alcohols based on the reduction of amino acid esters under mild conditions, employing NaBH4 in the presence of methanol. The reactions occurred in a short time (15–20 min) and provide yields of 50–95%.

Benzyl N-((S)-2-hydr­oxy-1-{N′-[(E)-2-methoxy­benzyl­idene]hydrazinecarbon­yl}eth­yl)carbamate from synchrotron data

A U-shaped conformation is found in the title compound, C19H21N3O5, with the benzene rings lying to the same side of the molecule; the dihedral angle between them is 10.83 (16)°. The dihedral angle formed between the hydrazinecarbonyl and carbamate residues is 68.42 (13)°. The carbonyl groups lie approximately at right angles to each other [O—C⋯C—O pseudo torsion angle of 107.7 (3)°], and the conformation about the C12=N3 bond [1.279 (4) Å] is E. An intramolecular Ncb—H⋯Ohy (cb = carbmate and hy = hydroxy) hydrogen bond occurs, generating an S(6) loop. In the crystal, intermolecular Oh—H⋯Oca (ca = carbonyl) and Nhz—H⋯Oca (hz = hydrazine) hydrogen bonds lead to the formation of a supramolecular chain, two molecules thick, which propagates along the a axis; these are connected by C—H⋯Oca contacts.

Lamivudine, an important drug in aids treatment

Lamivudine, an L-nucleoside, has been considered the cornerstone of antiretroviral therapy programs considering its favorable efficacy, convenient dosing, and safety profile. The low incidence of side effects in comparison with D-nucleoside analogs is due to the presence of sulfur and also to its stereochemistry difference. Considering the importance of lamivudine especially in acquired immune deficiency syndrome treatment, but also in hepatitis B infection (HBV), two critical diseases nowadays, the purpose of this article is to highlight different aspects and synthetic strategies of this important drug.

Pyrrole-2-carbaldehyde isonicotinoylhydrazone monohydrate redetermined at 120 K

In the title compound, C11H10N4O.H2O, there are five independent hydrogen bonds, of O-H...O, O-H...N and N-H...O types, which link the components into complex sheets parallel to (001).

4-[(2-Chloro-ethyl)amino]quinolinium chloride monohydrate.

In the title salt hydrate, C11H12ClN2 +·Cl−·H2O, the quinolinium core is essentially planar (r.m.s. deviation = 0.027 Å) with the chloroethyl side chain being almost orthogonal to the core [C—N—C—C torsion angle = −80.0 (3)°]. In the crystal packing, the water molecule bridges three species, forming donor interactions to two chloride anions and accepting a hydrogen bond from the quinolinium H atom. The chloride anion accepts a hydrogen bond from the amine N atom with the result that a two-dimensional supramolecular array is formed in the ac plane. A C—H⋯Cl interaction also occurs.