Twenty five years of strategies, methodologies and reactions in organic chemistry

An overview of the developments that occurred in the field of organic chemistry in Brazil in the last 25 years is presented. These developments are briefly compared to those observed worldwide, including some modern trends. The main source of information was the annual meeting of the Brazilian Chemical Society (RASBQ) covering the period 1979-2001 and the biennial Brazilian Meeting on Organic Synthesis (BMOS). All the contributions presented at these two meetings were classified according to six main indicatives, to permit a discussion about the past, present and future activities of Organic Chemistry in Brazil.748

Nitric oxide: properties and therapeutic use

Nitric oxide ( NO) is a substance that acts as a second-messenger and is associated with a number of important physiological functions such as regulation of the vascular tonus, immune modulation and neurotransmission. As a physiological mediator, alteration of its concentration level may cause pathophysiological disfunctions such as hypertension, septic shock and impotence. Possible therapeutic approaches are being developed to control NO levels in vivo. We review herein the main physical and chemical properties of NO, its biological functions and available chemical interventions to reduce and increment its physiological concentration levels. Recent developments in the field are also highlighted.10461054Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Ethyl 2-(4-methoxyphenyl)-6-oxa-3-azabicyclo[3.1.0]hexane-3-carboxylate: crystal structure and Hirshfeld analysis

The title compound, C14H17NO4, features an epoxide-O atom fused to a pyrrolidyl ring, the latter having an envelope conformation with the N atom being the flap. The 4-methoxyphenyl group is orthogonal to [dihedral angle = 85.02 (6)°] and lies to the opposite side of the five-membered ring to the epoxide O atom, while the N-bound ethyl ester group (r.m.s. deviation of the five fitted atoms = 0.0187 Å) is twisted with respect to the ring [dihedral angle = 17.23 (9)°]. The most prominent interactions in the crystal are of the type methine-C—H...O(carbonyl) and these lead to the formation of linear supramolecular chains along the c axis; weak benzene-C—H...O(epoxide) and methine-C—H...O(methoxy) interactions connect these into a three-dimensional architecture. The analysis of the Hirshfeld surface confirms the presence of C—H...O interactions in the crystal, but also the dominance of H...H dispersion contacts.</jats:p

3-Hydroxy-2-phenyl-2,3,3a,7a-tetrahydro-1H,5H-pyrano[3,2-b]pyrrol-5-one: crystal structure and Hirshfeld surface analysis

The title isoaltholactone derivative, C13H13NO3, has an NH group in place of the ether-O atom in the five-membered ring of the natural product. The five-membered ring is twisted about the N—C bond linking it to the six-membered ring, which has a half-chair conformation with the O atom connected to the ether-O atom lying above the plane defined by the remaining atoms. The dihedral angle between the mean planes of the rings comprising the fused-ring system is 75.10 (8)°. In the crystal, hydroxy-O—H...N(amine) hydrogen bonding sustains linear supramolecular chains along the a axis. Chains are linked into a three-dimensional architecture via amine-N—H...π(phenyl) and phenyl-C—H...O(hydroxy) interactions. The influence of the amine-N—H...π(phenyl) contact on the molecular packing is revealed by an analysis of the Hirshfeld surface

Dba-free" Palladium Intermediates Of The Heck-matsuda Reaction."

The dba-free Heck-Matsuda reaction was investigated via direct ESI-MS(/MS) monitoring. Palladium species involved in the reduction of Pd(II) during a Wacker type reaction and several dba-free arylpalladium transient complexes were detected and characterized. Based on these findings, a more comprehensible catalytic cycle for this pivotal reaction is suggested.113277-8

(1R,2S,5R)-5-Methyl-2-[2-(4-nitrophenyl)propan-2-yl]cyclohexyl 2-(4-methoxyphenyl)-2,5-dihydro-1H-pyrrole-1-carboxylate: crystal structure and Hirshfeld analysis

In the title compound, C28H34N2O5, the adjacent ester and nitrobenzene substituents are connected via an intramolecular methylene-C—H. ...(nitrobenzene) interaction and the molecule approximates to a U-shape. The dihydropyrrole ring (r.m.s. deviation = 0.003 A ˚ ) is almost co-planar with the carboxylate residue [Cm—N—C1—Oc (m = methine, c = carboxyl) torsion angle = 1.8 (4).] but is orthogonal to the 4-methoxybenzene ring [dihedral angle = 84.34 (17).]. In the crystal, methylene-C—H. ...O(carbonyl) interactions lead to linear supramolecular chains along the b-axis direction, which pack without directional interactions between them. The analysis of the calculated Hirshfeld surface points to the importance of weak interatomic H. . .H, O. . .H/H. . .O and C. . .H/H. . .C contacts in the crystal

(4-Nitrophenyl)methyl 2,3-dihydro-1H-pyrrole-1-carboxylate: crystal structure and Hirshfeld analysis

In the title compound, C12H12N2O4, the dihydropyrrole ring is almost planar (r.m.s. deviation = 0.0049 A ˚ ) and is nearly coplanar with the adjacent C2O2 residue [dihedral angle = 4.56 (9˚)], which links to the 4-nitrobenzene substituent [dihedral angle = 4.58 (8˚)]. The molecule is concave, with the outer rings lying to the same side of the central C2O2 residue and being inclined to each other [dihedral angle = 8.30 (7˚)]. In the crystal, supramolecular layers parallel to (105) are sustained by nitrobenzene-C—H...O(carbonyl) and pyrrole-C—H...O(nitro) interactions. The layers are connected into a three- dimensional architecture by π(pyrrole)–π(nitrobenzene) stacking [inter-centroid separation = 3.7414 (10) A ˚ ] and nitro-O...π(pyrrole) interactions

Crystal structure of tert-butyl (1S,2R,5R)-2-(hydroxymethyl)-4-(4-methoxyphenyl)-6-oxa-3-azabicyclo[3.1.0]hexane-3-carboxylate, C17H23NO5

C17H23NO5, monoclinic, P21 (no. 4), a = 6.0479(9) Å, b = 9.7032(10) Å, c = 14.711(2) Å, β = 94.174(9)°, V = 861.0(2) Å3, Z = 2, Rgt(F) = 0.0440, wRref(F2) = 0.1436, T = 293(2) K

[(2S,5R)-1-Methyl-5-phenyl­pyrrolidin-2-yl]diphenyl­methanol

In the title compound, C24H25NO, the phenyl and diphenyl­methanol substituents are syn to each other. The pyrrolidine ring has an envelope conformation with the flap atom being the C atom bearing the phenyl substituent. The hy­droxy group forms an intra­molecular hydrogen bond with the pyrrolidine N atom, and the phenyl rings lie to same side of the mol­ecule. The crystal packing features C—H⋯π inter­actions. Two slightly displaced co-planar orientations were found for one of the phenyl rings; the major component had a site-occupancy factor of 0.782 (15)