Cupric sulfate pentahydrate (CuSO4·5H2O): a mild and efficient catalyst for tetrahydropyranylation/depyranylation of alcohols and phenols
作者:Abu T. Khan、Lokman H. Choudhury、Subrata Ghosh
DOI:10.1016/j.tetlet.2004.08.141
日期:2004.10
Various alcohols and phenols can be smoothly converted to the corresponding THP ethers using 20 mol % CuSO4·5H2O under mild reaction conditions at room temperature. Some of the major advantages of this procedure are nonaqueous work-up, very good yields, less expensive catalyst and compatibility with other protecting groups.
Silylstannylation of Allenes and Silylstannylation−Cyclization of Allenynes. Synthesis of Highly Functionalized Allylstannanes and Carbocyclic and Heterocyclic Compounds
作者:Ramaiah Kumareswaran、Seunghoon Shin、Isabelle Gallou、T. V. RajanBabu
DOI:10.1021/jo049010z
日期:2004.10.1
silicon−tin reagents to undergo the cyclization illustrate the scope and limitations of the reaction. Based on the isolation of intermediates, a mechanism for the formation of the cyclic compounds is proposed. Model transition states to explain the stereoselectivity in cyclization of substituted allenynes are provided. Further elaboration using the vinyltin and vinylsilane moieties should lead to highly functionalized
Synthesis of Substituted Isoquinolines via Nickel-Catalyzed [2+2+2] Cycloaddition of Alkynes and 3,4-Pyridynes
作者:Yoshihiro Sato、Toshihiko Iwayama
DOI:10.3987/com-09-s(s)126
日期:——
A novel methodology for the synthesis of substituted isoquinolines via a nickel(0)-catalyzed [2+2+2] cycloaddition of 3,4-pyridynes with two molecules of alkyne has been established. In this reaction, it was found that 2-butyn-1,4-diol derivatives and 1,3-diynes are suitable as substrates and that a propargylic oxygen functionality in alkynes is essential for the reactivity and the selectivity of the
Silica-Supported Perchloric Acid (HClO<sub>4</sub>-SiO<sub>2</sub>): A Versatile Catalyst for Tetrahydropyranylation, Oxathioacetalization and Thioacetalization
作者:Abu Khan、Tasneem Parvin、Lokman Choudhury
DOI:10.1055/s-2006-942465
日期:2006.8
A simple and convenient syntheticprotocol for the protection of hydroxyl group as tetrahydropyranyl ether as well as carbonyl functionality as oxathioacetal and thioacetal has been achieved using a catalytic amount of silica-supported perchloric acid undersolvent-freeconditions. This protocol has many advantages compared to currently available methodologies in terms of simplicity, yield, reaction
Highly Selective Cobalt-Mediated [6 + 2] Cycloaddition of Cycloheptatriene and Allenes
作者:Hervé Clavier、Karel Le Jeune、Innocenzo de Riggi、Alphonse Tenaglia、Gérard Buono
DOI:10.1021/ol102783x
日期:2011.1.21
[6 + 2] Cycloadditions between cycloheptatrienes with allenes have been investigated. Cobalt salts were found to promote this transformation efficiently. Moreover, this reaction was found to be highlyselective since only one regioisomer was obtained with an excellent E/Z-selectivity.