Sulfonated rice husk ash (RHA-SO3H): A highly powerful and efficient solid acid catalyst for the chemoselective preparation and deprotection of 1,1-diacetates
摘要:
Rice husk ash (RHA), as a source of amorphous silica, was treated with chlorosulfonic acid and sulfonated rice husk ash (RHA-SO3H) as a highly powerful solid acid catalyst was obtained and characterized with a variety of techniques including IR, TGA, SEM, XRD, pH analysis, Hammett acidity function and BET method. This solid acid showed excellent catalytic activity for the protection and deprotection of aldehydes with Ac2O at room temperature under solvent free conditions. The procedure gave the products in excellent yields in very short reaction times and good to high yields. Also this catalyst can be reused for several times without loss of its catalytic activity. (C) 2013 Elsevier B.V. All rights reserved.
Highly Regio- and Enantioselective Reductive Coupling of Alkynes and Aldehydes via Photoredox Cobalt Dual Catalysis
作者:Yan-Lin Li、Shi-Qi Zhang、Jie Chen、Ji-Bao Xia
DOI:10.1021/jacs.1c03527
日期:2021.5.19
A Co-catalyzed highly regio- and enantioselective reductive coupling of alkynes and aldehydes has been developed under visible light photoredox dual catalysis. A variety of enantioenriched allylic alcohols have been obtained by using unsymmetrical internal alkynes and commercially available catalyst, chiral ligand, and reagents. It is noteworthy that this approach has considerable advantages, such
在可见光光氧化还原双催化下开发了一种共催化的炔烃和醛的高度区域选择性和对映选择性还原偶联。通过使用不对称内部炔烃和市售催化剂、手性配体和试剂,已经获得了多种对映体富集的烯丙醇。值得注意的是,这种方法具有相当大的优势,例如出色的区域-(> 40 个示例> 95:5)、立体-(高达> 95:5 E / Z)和对映选择性(92-99% ee,> 35个例子)控制,反应条件温和,底物范围广,官能团相容性好,使其对映选择性炔-醛还原偶联反应有了很大的改进。
Succinimidinium hydrogensulfate ([H-Suc]HSO4) as a new, green and efficient ionic liquid catalyst for the synthesis of tetrahydrobenzimidazo[2,1-b]quinazolin-1(2H)-one, 1-(benzothiazolylamino)phenylmethyl-2-naphthol, 1, 8-dioxo-octahydroxanthene and bis(indolyl)methane derivatives
作者:Omid Goli-Jolodar、Farhad Shirini
DOI:10.1007/s13738-016-0822-1
日期:2016.6
In this work, succinimidinium hydrogensulfate ([H-Suc]HSO4), a newly reported Brönsted acidic ionic liquid, is used as an efficient and reusable catalyst in the synthesis of tetrahydrobenzimidazo[2,1-b]quinazolin-1(2H)-ones, 1-(benzothiazolylamino)phenylmethyl-2-naphthols, 1,8-dioxo-octahydroxanthenes and bis(indolyl)methanes. All reactions were performed during relatively short reaction times with
在这项工作中,新报道的布朗斯台德酸性离子液体硫酸氢琥珀酰亚胺([H-Suc] HSO 4)在合成四氢苯并咪唑并[ 2,1- b ]喹唑啉-1(2 H)中用作有效且可重复使用的催化剂。)-,1-(苯并噻唑基氨基)苯基甲基-2-萘酚,1,8-二氧-八氢氧杂蒽和双(吲哚基)甲烷。所有反应均在相对短的反应时间内进行,并具有优异的收率。通过IR,1 H NMR和13 C NMR光谱对产物的结构进行表征,并通过比较真实样品进行确认。
Palladium-Catalyzed Reaction of Haloarenes with Diarylethynes: Synthesis, Structural Analysis, and Properties of Methylene-Bridged Arenes
作者:Che-Wei Lee、En-Chih Liu、Yao-Ting Wu
DOI:10.1021/acs.joc.5b02111
日期:2015.11.6
Fluorenes and methylene-bridged polyarenes were easily and efficiently synthesized from haloarenes (or aryl triflates) and diarylethynes by a one-pot, two-step procedure. This protocol involves the palladium-catalyzed cycloisomerization and a subsequent base-mediated retro-aldol condensation. A major advantage is that the starting materials need not have ortho functional groups to complete the annulation
Efficient synthesis of 3-substituted indoles through a domino gold(I) chloride catalyzed cycloisomerization/C3-functionalization of 2-(alkynyl)anilines
作者:C. Praveen、K. Karthikeyan、P.T. Perumal
DOI:10.1016/j.tet.2009.09.019
日期:2009.11
An efficient synthesis of 3-substituted indoles by a sequential approach involving gold(I) chloride catalyzed cycloisomerization/bis-addition and conjugate addition of 2-(alkynyl)anilines has been accomplished. A variety of 2-(alkynyl)anilines, aldehydes, isatins and nitroolefins undergo this overall process in good to excellent yields. This methodology represents an effective alternative to the classical
Gold(I)-catalyzed sequential cycloisomerization/bis-addition of o-ethynylanilines: an efficient access to bis(indolyl)methanes and di(indolyl)indolin-2-ones
作者:C. Praveen、Y. Wilson Sagayaraj、P.T. Perumal
DOI:10.1016/j.tetlet.2008.11.086
日期:2009.2
An efficient synthesis of bis(indolyl)methanes and di(indolyl)indolin-2-ones has been developed by a sequential approach involving gold(I)-catalyzedcycloisomerization/bis-addition of o-ethynylanilines with various aldehydes and isatins, respectively. This methodology opens clean and synthetically competitive alternative to the already established procedures of the synthesis of bis(indolyl)methanes