Synthesis of functionalized chromene and spirochromenes using l -proline-melamine as highly efficient and recyclable homogeneous catalyst at room temperature
commercially cheap l-proline and melamine for the synthesis of chromenes and spirochromenes (spirooxindoles) via multicomponent reactions at room temperature. Systematic studies were conducted in order to achieve desired reactivity and recyclability of the catalyst using various α-amino acids and aromatic amines as donor-acceptor pairs. Among the screened combinations, l-proline and melamine (3:1 ratio;
Abstract The synthesis of biologically valuable spirooxindoles and 4H-pyrans is described under catalyst-free conditions through sequential Knoevenagel–Michael–cyclization reactions from isatin or aromatic aldehyde, malononitrile, and 1,3-dicarbonyl compounds. The reaction conditions are very simple, providing excellent yield. [Supplementary materials are available for this article. Go to the publisher's
One-pot synthesis of 2-amino-3-cyano-4<i>H</i>-pyrans and pyran-annulated heterocycles using sodium citrate as an organo-salt based catalyst in aqueous ethanol
作者:Aiborlang Thongni、Pynskhemborlang T. Phanrang、Arup Dutta、Rishanlang Nongkhlaw
DOI:10.1080/00397911.2021.1998535
日期:2022.1.2
shorter reaction time, utilization of eco-friendly solvents, operational simplicity, mild reaction conditions, and maximum product yield. Moreover, the use of sodium citrate as an easily available, cheap and benign catalyst plays a pivotal role from a green perspective, considering its high recyclability and easy recovery. Therefore, this present methodology offers numerous possibilities in terms of large-scale
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.