Silvio Cunha

The Michael Reaction of Enaminones with N-(p-tolyl)-maleimide: Synthesis and Structural Analysis of Succinimide-enaminones

Succinimido enaminonas foram sintetizadas atraves da reacao de enaminonas e a N-(p-toluil)-maleimida em rendimento moderado a bom. A acao antibacteriana destes compostos contra E. coli e S. aureus foi avaliada, mas a atividade antibacteriana nao foi significativa. A regioquimica das succinimido enaminonas foi racionalizada empregando-se a teoria dos orbitais moleculares de fronteira. A estrutura cristalina de um dos compostos foi determinada e foram observadas varias pontes de hidrogenio inter- e intramolecular do tipo NH...O e CH...O.

Reaction of Diphenylcyclopropenone with N-Acylamidine Derivatives. Synthetic and Mechanistic Implications

In this work, the reactivity of cyclopropenones toward N-acylamidine derivatives was investigated. Diphenylcyclopropenone reacted with N-benzoylacetamidine and N-(methoxycarbonyl)benzamidine affording 1,2-dihydro-3H-pyrrol-3-ones in moderate yields. However, alkylphenylcyclopropenone did not react. The formation of the compounds is examined mechanistically within frontier molecular orbital considerations.

A semiempirical quantum mechanical approach towards understanding of cyclopropenone reactivity

Abstract The results of semiempirical molecular orbital calculations performed on several cyclopropenones employing the MNDO, AM1, and PM3 molecular models are presented. The AM1 method, which best reproduces structural properties, is used to calculate electronic parameters for a series of cyclopropenones. The use of these parameters for the evaluation of reactivity is discussed.

Alkyl-C versus phenyl-C reactivity in unsymmetrical cyclopropenones. Reaction of methylphenylcyclopropenone with pyrazoles.

Abstract Methylphenylcyclopropenone ( 1 ) reacts with pyrazole and 3,5-dimethylpyrazole to afford ketones ( 2 ) resulting from initial nucleophilic attack at methyl-C, in agreement with an AM1 calculation performed on 1 . Intermediacy of dipolar species 3 accounts for products and allows incorporation of other nucleophiles (2-aminothiazoole, 2-amino-4-methylpyridine, and o-phenylenediamine).

On the Reactivity of α-(Triphenylphosphoranylidene)-benzylphenylketene with Nitrogen Compounds: Synthetic and Mechanistic Implications

The reactivity of α-(triphenylphosphoranylidene)-benzylphenylketene, a stabilized phosphorus ylide derived from diphenylcyclopropenone, toward nitrogen compounds was investigated. Particularly, the reaction of diethyl azodicarboxylate with α-(triphenylphosphoranylidene)-benzylphenylketene provides a new route to polysubstituted N-acyl carbamates.

On the reactivity of triphenylphosphoranylidenesuccinic anhydride with nitrogen nucleophiles: a new synthetic route to nitrogen-containing phosphonium salts

The reactions of triphenylphosphoranylidenesuccinic anhydride with amines, hydrazines and dipolar nitrogen nucleophiles were investigated, and a new method of synthesis of phosphonioum salts containing the fragment RNHC(C=O)CH2CH2PPh3 is described.

catena-Poly[[[1-benzoyl-2-(2-hydroxyethyl)-3-(2-pyridyl)guanidine]chloridocopper(II)] chloride 0.61-hydrate]

The title copper(II) complex, {[CuCl(C(15)H(16)N(4)O(2))]Cl.0.61H(2)O}(n), is a one-dimensional zigzag coordination polymer structure extending along the (010) direction. The Cu(II) atom has a square-pyramidal geometry, where the basal plane is formed by two cis N atoms and one O atom from the ligand, and by a Cl atom. The apical position is occupied by a carbonyl O atom from a symmetry-related molecule. In the crystal structure, there are O-H...Cl and N-H...Cl hydrogen bonds, which link parallel polymer chains along the c direction, so building a two-dimensional structure via the interstitial Cl atoms.