Silica-bonded 5-n-propyl-octahydro-pyrimido[1,2-a]azepinium chloride (SB-DBU)Cl as a highly efficient, heterogeneous and recyclable silica-supported ionic liquid catalyst for the synthesis of benzo[b]pyran, bis(benzo[b]pyran) and spiro-pyran derivatives, By Abdolkarim Zare

Research

Title	Silica-bonded 5-n-propyl-octahydro-pyrimido[1,2-a]azepinium chloride (SB-DBU)Cl as a highly efficient, heterogeneous and recyclable silica-supported ionic liquid catalyst for the synthesis of benzo[b]pyran, bis(benzo[b]pyran) and spiro-pyran derivatives
Type	Article
Keywords	Silica-bonded 5-n-propyl-octahydropyrimido[1,2-a]azepinium chloride (SB-DBU)Cl; 4H-benzo[b]pyran; Spiro-pyrans; Silica-supported catalyst; Malono derivatives
Journal	JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL
DOI	10.1016/j.molcata.2013.02.022
Researchers	Alireza Hasaninejad (First researcher) , Nooshin Golzar (Second researcher) , Maryam Beyrati (Third researcher) , Abdolkarim Zare (Fourth researcher) , Mohammad Mahdi Doroodmand (Fifth researcher)

Abstract

The reaction of 3-chloropropyl silica (SilprCl) with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in dry acetone affords silica-bonded 5-n-propyl-octahydro-pyrimido[1,2-a]azepinium chloride (SB-DBU)Cl as a new silica-supported ionic liquid catalyst. Afterward, (SB-DBU)Cl is used for the efficient synthesis of 4H-benzo[b]pyran derivatives via the one-pot, three-component reaction of carbonyl compounds (cyclohexane-1,3-dione, 5,5-dimethylcyclohexane-1,3-dione or 3-methyl-1-phenyl-2-pyrazolin-5-one) with aromatic aldehydes and alkylmalonates. Moreover, some novel bis(benzo[b]pyran)s and a broad range of structurally diverse spiro-pyrans containing oxindole and/or quinoxaline moiety in their structures are synthesized using (SB-DBU)Cl. The catalyst is recycled and reused fifteen times with unchanged yield.