Issa Yavari

A NEW AND EFFICIENT ROUTE TO 4-CARBOXYMETHYLCOUMARINS MEDIATED BY VINYLTRIPHENYLPHOSPHONIUM SALT

Abstract Protonation of the reactive 1:1 intermediate produced in the reaction between triphenylphosphine and dimethyl acetylenedicarboxylate by substituted phenols leads to a vinyltriphenylphosphonium salt, which undergoes aromatic electrophilic substitution reaction with the phenolate conjugate base to produce 4-carboxymethylcoumarins in fairly high yields.

Synthesis of Densely Functionalized N-Hydroxypyrroles Mediated by Vinyltriphenylphosphonium Salt

Abstract Protonation of the reactive 1:1 intermediates produced in the reaction between triphenylphosphine and dialkyl acetylenedicarboxlates by butane-2,3-dione monoxime leads to vinyltriphenylphosphonium salts, which undergo intramolecular Wittig reaction to produce dialkyl 2,3-dimethyl-N-hydroxypyrrole-4,5-dicarboxylates in fairly high yields.

ONE-POT STEREOSELECTIVE SYNTHESIS OF DIMETHY (2-HYDROXY-4,4-DIMETHYLCYCLOHEX-1-EN-6-ONE-1-YL)-3-(DIPHENYLPHOSPHONATO)BUTANEDIOATE

Abstract Protonation of the reactive intermediate produced in the reaction between triphenyl phosphite and dimethyl acetylenedicarboxylate by 5,5-dimethylcyclohexane-1,3-dione leads to vinyltriphenoxyphosphonium cation, which undergoes an addition reaction with the enolate anion of the CH-acid to produce the title compound in high yield.

Triphenylphosphine Catalyzed Stereoselective Synthesis of O-Vinyloximes

Abstract The conjugate addition of oximes to ethyl propiolate proceeds under neutral conditions in presence of a catalytic amount of triphenylphosphine to give the corresponding O-vinyloximes in good yields.

New and efficient synthesis of dialkyl 2-[1-p-nitrophenyl-2-(alkylamino)-2-oxoethyl]malonates

The condensation product of Meldrums acid and 4-nitrobenzaldehyde reacts smoothly with alkyl isocyanides in the presence of alcohols to produce dialkyl 2-[1-p-nitrophenyl-2-(alkylamino)-2-oxoethyl]malonates in excellent yield. This reaction provides a useful synthetic route to highly functionalized amidodiesters.

Force-field calculations for some unsaturated cyclic hydrocarbons

Abstract Boyds iterative force-field computer program, with modified parameters, has been used to calculate strain energies in the following molecules: trans-cyclooctene, cyclohexene, melhylenecyclohexane, 1,3,5- and 1,3,6-cyclooctatriene, and cyclononyne. Both static and dynamic aspects of the conformational properties of these molecules have been investigated in detail, and the results are discussed in conjunction with extant experimental data and previous force-field calculations.

STEREOSELECTIVE SYNTHESIS OF HIGHLY FUNCTIONALIZED CYCLOBUTENES. A FACILE ROUTE TO ELECTRON-DEFICIENT 1,3-DIENES

Abstract Acetoacetanilide undergoes a smooth reaction with triphenylphosphine and dialkyl acetylenedicarboxylates to produce dialkyl 2-(acetoacetanilide-2-yl)-3-(triphenylphosphoranilidene)-butandioates, which undergo intramolecular Wittig reaction to produce 2-methyl-3-( N -phenylcarbonyl)-1,4-dialkoxycarbonylcyclobutenes. These cyclobutene derivatives undergo electrocyclic ring-opening reactions in boiling toluene to produce highly electron-deficient 1,3-dienes.

Vinyltriphenylphosphonium salt mediated synthesis of functionalized coumarins

Abstract Protonation of the reactive 1:1 intermediate produced in the reaction between triphenylphosphine and dimethyl acetylenedicarboxylate by hydroquinone, resorcinol, catechol or pyrogallol leads to vinylphosphonium salts, which undergo Michael addition with the conjugate base of the hydroxy acid to produce highly functionalized 2-oxo-2 H -chromene derivatives in good yields.

An efficient diastereoselective one-pot synthesis of dihydrofuro[2′,3′:2,3]indeno[2,1-b]furan derivatives

Abstract Ninhydrin reacts smoothly with dialkyl acetylenedicarboxylates in the presence of triphenylphosphine to produce C 2 -symmetric tetra-alkyl 2,5-dihydrofuro[2′,3′:2,3]indeno[2,1- b ]furan-1,2,5,6-tetracarboxylates in excellent yields.

A novel approach to the synthesis of highly functionalized furans

Abstract The reaction of dibenzoylacetylene and enol systems, such as acetylacetone, 5,5-dimethylcyclohexane-1,3-dione, 1-naphthol, 2-naphthol, 2,7-dihydroxynaphthalene, or 8-hydroxyquinoline in the presence of triphenylphosphine leads to tetrasubstituted furans in 65–83% yields.