Novel One-Pot, Four-Component Condensation Reaction: An Efficient Approach for the Synthesis of 2,5-Disubstituted 1,3,4-Oxadiazole Derivatives by a Ugi-4CR/aza-Wittig Sequence

Abstract

A novel and efficient method has been developed for the synthesis of 2,5-disubstituted 1,3,4-oxadiazole derivatives using (N-isocyanimino)triphenylphosphorane, a secondary amine, a carboxylic acid, and an aromatic aldehyde in CH(2)Cl(2) at ambient temperature in high yields without using any catalyst or activation. The procedure provides an alternative method to the synthesis of fully substituted 1,3,4-oxadiazole derivatives.

Synthesis of N-substituted Acridinediones and Polyhydroquinoline Derivatives in Refluxing Water

“…Multicomponent one-pot reactions as a kind of economical and efficient procedure has been widely used for the synthesis of heteroatom-containing compounds [12][13][14]. Moreover, organic reactions in water as the reaction medium, which represents a clean, economical, and environmental-safe protocol, has attracted considerable attention.…”

Four-Component Preparation of Disubstituted 1,3,4-Oxadiazoles from (N-isocyanimino)triphenylphosphorane, Phenylacetylenecarboxylic Acid, Biacetyl and Primary Amines

“…16,17 In recent years, we have confirmed a one-pot method for the preparation of organophosphorus compounds. [18][19][20][21][22][23][24] As part of our ongoing program to develop efficient and robust methods for the preparation of heterocyclic compounds, [25][26][27][28][29][30][31][32][33][34][35][36][37][38] we wish to report the preparation of a new class disubstituted 1,3,4-oxadiazole derivatives 5a-j by a novel four-component condensation reaction of biacetyl (1), primary amine 2, (Nisocyanimino)triphenylphosphorane (4) and phenylacetylenecarboxylic acid (3) in excellent yields under neutral conditions (Scheme 1).…”

“…This intermediate may be attacked by conjugate base of the carboxylic acid to form 1:1:1 adduct 9. The intermediate 9 may undergo intramolecular aza-Wittig reaction [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] of iminophosphorane moiety with the ester carbonyl to afford the isolated sterically congested 1,3,4-oxadiazole derivatives 5 by removal of triphenylphosphine oxide (6) from intermediate 10.…”

Efficient and Selective Construction of Pyrrolo[3,2-d]pyrimidine Derivatives

“…[11][12][13] On the other hand, the aza-Wittig-mediated annulation strategy has received increased attention in view of their utility in the synthesis of nitrogen-containing heterocyclic compounds. [14][15][16][17][18][19][20][21][22] We have been interested in the synthesis of fused heterocycles via aza-Wittig reaction for some time, [23][24][25][26][27][28][29] with the aim of searching for new lead compounds. In the early studies, we reported the synthesis of pyrrolo[3,2-d]-pyrimidines from 3-amino-2-carboxylpyrroles, 30 and the synthesis of pyrrolo [3,4-d]pyrimidines from 4-amino-3-carboxylpyrroles.…”