A mild, simple and convenient procedure for the synthesis of spiro-oxindole heterocycles containing fused 4H-pyran ring and also bis-2-amino-4H-pyrans derivatives was described using C4(DABCO-SO3H)2·4Cl as a nano, efficient, cheap, and reusable catalyst under mild and homogeneous conditions.
Perchloric acid modified-cellulose: a versatile, novel and biodegradable heterogeneous solid acid catalyst for single-pot synthesis of novel bis-pyran annulated heterocyclic scaffolds under solvent-free conditions
作者:Tabassum Khan、Zeba N. Siddiqui
DOI:10.1039/c4nj00529e
日期:——
the synthesis of novel bis-pyran annulated heterocyclic scaffolds (4a–r) using cellulose–perchloric acid (CPA) as an eco-friendly, biodegradable and recyclable catalyst in excellent yields undersolvent-freeconditions. Other remarkable features of this environmentally benign protocol are short reaction time, a wide range of functional group tolerance, use of inexpensive heterogeneouscatalyst, and
1-Methylimidazolium tricyanomethanide {[HMIM]C(CN)3} as a nano structure and reusable molten salt catalyst for the synthesis of tetrahydrobenzo[b]pyrans via tandem Knoevenagel-Michael cyclocondensation and 3,4-dihydropyrano[c]chromene derivatives
作者:Mohammad Ali Zolfigol、Neda Bahrami-Nejad、Fatemeh Afsharnadery、Saeed Baghery
DOI:10.1016/j.molliq.2016.06.069
日期:2016.9
An expeditious, experimentally simple and rapid 1-methylimidazolium tricyanomethanide [HMIM]C(CN)3} nano molten salt (NMS) catalyzed tandem Knoevenagel-Michael cyclocondensation procedure for the synthesis of tetrahydrobenzo[b]pyrans was described via reaction between dimedone, aromatic aldehyde and malononitrile under solvent-free conditions at room temperature. Furthermore, 3,4-dihydropyrano[c]chromene
通过二甲酮之间的反应,描述了一种快速,实验简单且快速的三氰基甲基1-甲基咪唑鎓[HMIM] C(CN)3 }纳米熔融盐(NMS)催化串联Knoevenagel-Michael环缩合反应合成四氢苯并[ b ]吡喃的方法,室温下在无溶剂条件下的芳族醛和丙二腈。此外,在相同条件下,以[HMIM] C(CN)3 } NMS为催化量,通过4-羟基香豆素,芳香醛和丙二腈的缩合反应合成了3,4-二氢吡喃并[ c ]色烯衍生物。
Heterogeneous ditopic ZnFe<sub>2</sub>O<sub>4</sub>catalyzed synthesis of 4H-pyrans: further conversion to 1,4-DHPs and report of functional group interconversion from amide to ester
Highly stable, environmentally benign ZnFe2O4 nanopowder was prepared, characterized and applied in the one-pot, three-component synthesis of 4H-pyrans in water. The ZnFe2O4 catalyst provides both acidic (Fe3+) and basic functionalities (O2−) as the reaction requires. The advantages of this method lie in its simplicity, cost effectiveness, environmental friendliness and easier scaling up for large scale synthesis. Water was exploited both as a reaction medium as well as a medium for synthesis of the catalyst. Moreover, water was the only byproduct. The present report puts forward an application of 4H-pyrans for the synthesis of 1,4-DHPs. This is the first attempt towards the synthesis of 4H-pyran-3-carboxylate from 4H-pyran-3-carboxamide. The corresponding functional group interconversion from amide to ester is rare in organic synthesis.
Mono- and Bis-2-amino-4H-pyrans: Alum Catalyzed Three- or Pseudo Five-Component Reaction of 4-Hydroxycoumarin, Malononitrile and Aldehydes
作者:Ali Reza Karimi、Cyrus Eslami
DOI:10.2174/157017811794697421
日期:2011.2.1
An efficient method for the three- or pseudofive-componentsynthesis of mono- and bis-2-amino-4H-pyrans in excellent yields using Alum (KAl(SO4)2.12H2O) as recyclable catalyst is described. The present methodology offers several advantages such as excellent yields, simple procedures, shorter reaction times, milder conditions and the catalysts exhibited remarkable reusable activity.