Diastereoselective Synthesis of trans-2,3-Dihydrofurans with Pyridinium Ylide Assisted Tandem Reaction

Abstract

An efficient synthetic procedure for the preparation of fused 2,3-dihydrofuran derivatives was developed with the assistance of pyridinium ylide. A sequential one-pot, two-step tandem reaction starting from pyridine, aromatic aldehyde, dimedone, or 4-hydroxycoumarin and alpha-phenacyl bromide or p-nitrobenzyl bromide with triethylamine as catalyst proceeded smoothly in acetonitrile. (1)H NMR spectroscopy and single-crystal analysis demonstrated that the obtained 2,3-dihydrofurans are trans isomers.

Synthesis of furo[3,2-c]coumarins under microwave irradiation using nano-CoFe2O4@SiO2–PrNH2 as an efficient and magnetically reusable catalyst

“…Thus, only the trans-isomer of 2,3-dihydrofuran is obtained. 14,15 Pyridine plays very important role in this proposed reaction mechanism. It stabilizes the ylide during the attack on intermediate I and acts as a good leaving group in the zwitterionic salt II to finish the intramolecular substitution reaction.…”

“…It has been established that in cis-2,3-dihydrofuran the vicinal coupling constant of the two methine protons is 7-10 Hz, while in trans-2,3-dihydrofuran the vicinal coupling constant is 4-7 Hz. 15 Consequently, the trans isomer of 2,3-dihydrofuran was obtained as the only product. The structure of compound 4c was confirmed by single crystal X-ray analysis (Fig.…”

2-Bromoacetophenone

“…4 (C) Das et al 5 developed a convenient method for the rapid and high-yielding synthesis of thiazoles and amino thiazoles by treatment of 2-bromoacetophenone with thioamides or thiourea in the presence of ammonium-12-molybdophosphate (AMP) at room temperature. (D) An efficient synthetic procedure for fused 2,3-dihydrofuran derivatives was developed by Chao-Guo Yan and co-workers 6 with the assistance of pyridinium ylide. A sequential one-pot, two-step tandem reaction starting from pyridine, aromatic aldehyde, dimedone or 4-hydroxy coumarin and 2-bromoacetophenone with triethyl amine as catalyst proceeded smoothly in acetonitrile.…”

A concise synthesis of furo[3,2-c]coumarins catalyzed by nanocrystalline ZnZr4(PO4)6 ceramics under microwave irradiation

“…Therefore, searching for efficient and concise techniques for the synthesis of furocoumarins through multicomponent reactions is a remarkable challenge. A number of methods has been developed for the synthesis of furocoumarins in the presence of diverse catalysts such as pyridine or a mixture of AcOH and AcONH 4 [9], ionic liquid [BMIm]OH [10], Pd(CF 3 COO) 2 [11], CuBr 2 [12], Nmethylimidazolium [13], Et 3 N [14], Bu 3 P and Et 3 N [15], polyphosphoric acid or KOH [16] and Rh 2 (OAc) 4 [17].…”