Cecilio Alvarez

Unusual Oxidative Dealkylation of Certain 4-Alkyl-1,4-Dihydropyridines With MnO2/Bentonite Using Microwave Irradiation, in the Absence of Solvent (II)

Abstract Several Hantzsch 4-alkyl-1,4- dihydropyridines have been oxidized to the corresponding aromatic systems. An unexpected mixture of 4-alkyl pyridines and/or dealkylated pyridines are formed.

Oxydation d'esters de Hantzsch, par le nouveau système HNO3/bentonite, et irradiation aux micro-ondes

Resume We report the aromatization of 1,4-dihydropyridines on using system HNO3/Bentonite 1 in absence of solvent, by irradiation of the samples in a microwave oven, obtaining excellent yields on very short times comparing with the normal procedures.

MnO2/Bentonite: A New Reactive for the Oxidation of Hantzsch'S Dihydropyridines Using Microwave Irradiation, in the Absence of Solvent (I)

Abstract The oxidation of several 4-aryl-1,4-dihydrophyridines with MnO2 on Mexican Bentonite, without solvents, using as energy source a microwave over is described.

Synthesis and X-ray structure of two isomeric aminocarbene complexes of tungsten containing a free carbon-carbon double bond

Abstract The reaction of allylamine with (CO)5WC(OCH2CH3)CH3 gives two isomeric aminocarbene complexes (CO)5WC(NHCH2CHCH2)CH3 2E and 2Z. Refluxing of a solution of this mixture in benzene gives the complexes (CO)4WC(η2NHCH2CHCH2)CH2 (3) and 2E, which have been separated. 2E was fully characterized by X-ray diffraction. Crystals of 2E are monoclinic, space group P21/n with Z = 4, a 7.188(3), b 14.312(2), c 12.530(2) A and β 91.06(3)°. The same mixture when treated with lithium diisopropylamide (LDA) followed by allyl bromide gives a mixture of (CO)5WC(N(CH2CHCH2)2)CH3 (4) and 2Z. These complexes were separated, and 2Z fully characterized by X-ray diffraction. Crystals of 2Z are monoclinic, space group P21/c, with Z = 4, a 6.593(5), b 14.584(3), c 13.323(1) A and β 95.13(4)°.

Tertiary stibines containing aromatic heterocycles and their silver complexes: synthesis and X-ray structures

Abstract The work presents the synthesis of tertiary stibines containing heterocyclic aromatic groups of general formula (2-C4H3X)3Sb where X=S (1), O (2) or NMe (3). These stibines were brominated to give corresponding dibromide and were complexed with silver(I) nitrate. The stibines, dibromides and their silver complexes were characterized by elemental analyses, IR, UV, mass, 1H, 13C, COSY, HETCOR NMR spectroscopy. Molecular structures of (2-C4H3S)3Sb (1); (2-C4H3S)3SbBr2 (4) and {Ag[(2-C4H3S)3Sb]2}NO3 (6) were determined by X-ray spectroscopy. This is the first X-ray crystallographic report on stibines containing heterocyclic aromatic groups and their silver complexes. The stibine (1) is pyramidal while its dibromide has trigonal bipyramidal structure. The silver complex (6) has a polymeric nature with NO3− acting as a bridging ligand.

Trans Influence of Triphenylstibine: Crystal Structures of cis‐[PtBr2(SbPh3)2], trans‐[PtBr(Ph)(SbPh3)2], [NMe4][PtBr3(SbPh3)], and cis‐[PtBr2(SbPh3)(PPh3)]

The work reports the unexpected reaction of diphenyldibromo antimonates (III) with PtCl2 and cis-[PtCl2(PPh3)2]. The reaction gives triphenylstibine containing PtII complexes viz. cis-[PtBr2(SbPh3)2] (1), trans-[[PtBr(Ph)(SbPh3)2] (2), [NMe4][PtBr3(SbPh3)] (3), and cis-[PtBr2(PPh3)(SbPh3)] (4). All the complexes were characterised by elemental analyses, IR, Raman, 195Pt NMR, FAB mass spectroscopy and X-ray crystallography. A plausible mechanism via the phenyl migration is proposed for the formation of these complexes. The average Pt–Br distance in 1 is 2.456(2) A, in 2 2.496 A(trans to Ph) while in 3 it is 2.476 A (trans to Sb) implying a comparable trans influence of Ph3Sb and Ph3P. Transeinflus von Triphenylantimon: Die Kristallstrukturen von cis-[PtBr2(SbPh3)2], trans-[PtBr(Ph)(SbPh3)2], [NMe4][PtBr3(SbPh3)] und cis-[PtBr2(SbPh3)(PPh3)] Es wird uber die unerwartete Reaktion von [Ph2SbBr2]– mit PtCl2 und cis-[PtCl2(PPh3)2] berichtet, die die Platin(II)-Komplexe cis-[PtBr2(SbPh3)2] (1), trans-[[PtBr(Ph)(SbPh3)2] (2), [NMe4][PtBr3(SbPh3)] (3) und cis-[PtBr2(PPh3)(SbPh3)] (4) ergibt. Die Komplexe werden durch Elementaranalyse, IR, Raman, 195Pt-NMR, FAB-Massenspektrometrie und Rontgenstrukturanalyse charakterisiert. Fur die Bildung der Komplexe wird ein Reaktionsmechanismus durch Ligandenaustausch vorgeschlagen. Der mittlere Pt–Br-Abstand betragt in 1: 2,456 A, in 2: 2,496 A (trans zu Ph), in 3: 2,476 A (trans zu Sb), was auf einen ahnlichen Transeinflus von Ph3Sb und Ph3P hinweist.

Carbonyl Compounds Regeneration with a Mexican Bentonite

Abstract Treatment of aldo and ketoximes with a bentonitic earth results in the formation of the carbonyl compounds. In some ketoximes there was evidence of Beckmann rearrangement.

A Direct Synthesis of Aromatic Nitriles from Aldehydes Using a Mexican Bentonite and Microwave or Infrared Irradiation, in Absence of Solvent

Abstract An efficient and simple procedure for the direct conversion of aromatic Aldehydes into the corresponding nitriles with hydroxylamine hydrochloride and a Mexican Bentonite via infrared or microwave irradiation.

Synthesis of 1,3,5-trioxanes : a new, simple method using a bentonitic earth as catalyst

Abstract A simple method for synthesizing aliphatic as well as aromatic 1,3,5-trioxanes using as catalyst a bentonitic earth is reported. The yields ranged from good to excellent.

Polyfluorothiolate derivatives of rhodium(I). Crystal and molecular structure of [Rh(μ-SC6HF4)(C8H12)]2

SummaryThe thiolato-bridged dinuclear compounds [Rh(μ-SR)-(COD)]2, where R=p-C6HF4 (1),p-C6H4F (2) and CF3 (3), are obtained from the chloro-bridged analogue by ligand exchange.Compound (1) crystallizes in the space group P1 with a=9.740(3)Å, b=11.642(4)Å, c=13.997(6)Å, α=103.87(3)°, β=106.98(3)° and γ=105.10(2)°; z=2. In this dinuclear molecule both Rh atoms have a square planar coordination sharing one edge, namely the two sulphur bridging atoms. The Rh—Rh separation of 2.96 Å is consistent with at most a very weak metal-metal interaction. Upon addition of CO the dimeric [Rh(μ-SR)(CO)2]2 (4), (5) and (6) are obtained, but addition of PPh3 affords the monomeric species [Rh(SR)(PPh3)-(COD)] (7), (8) and (9). Reactions of the dimeric tetracarbonyl derivatives with PPh3 vary with the nature of R; [Rh(μ-SR)(PPh3)(CO)]2 is obtained when R=p-C6H4F (10) and CF3 (11) but monomeric [Rh(SR)-(PPh3)(CO)2] (12) is produced when R=p-C6HF4. The latter mononuclear compounds, with R=p-C6H4F (13) and CF3 (14), are also formed by reaction of [Rh(SR)-(PPh3)(COD)] with CO.