Catalyst Control in Positional-Selective C–H Alkenylation of Isoxazoles and a Ruthenium-Mediated Assembly of Trisubstituted Pyrroles
作者:Pravin Kumar、Manmohan Kapur
DOI:10.1021/acs.orglett.9b00446
日期:2019.4.5
determining the positional selectivity in C–H alkenylation of isoxazoles. A cationic rhodium-mediated, strong-directing group promotes C(sp2)-H activation at the proximal aryl ring whereas, the palladium-mediated electrophilic metallation leads to the C(sp2)-H activation at the distal position of the directing group. Synthetic elaboration of this C–H alkenylation product via ruthenium and copper co-catalysis
One-Pot Copper(I)-Catalyzed Synthesis of 3,5-Disubstituted Isoxazoles
作者:Trond V. Hansen、Peng Wu、Valery V. Fokin
DOI:10.1021/jo050163b
日期:2005.9.1
3,5-Disubstituted isoxazoles are obtained in good yields by a convenient one-pot, three-step procedure utilizing a regioselective copper(I)-catalyzed cycloaddition reaction between in situ generated nitrile oxides and terminal acetylenes. Most functional groups do not interfere with the reaction, which can be performed in aqueous solvents without protection from oxygen. Since all reagents are used
Copper-doped silica cuprous sulfate (CDSCS) as a highly efficient heterogeneous nano catalyst for synthesis of 3,5-disubstituted isoxazoles
作者:M. N. Soltani Rad、S. Behrouz、M. A. Faghihi
DOI:10.1007/s13738-013-0307-4
日期:2014.4
A facile and highly efficient protocol for 1,3-dipolar cycloaddition of in situ generated nitrile oxides with terminal alkynes catalyzed by copper-doped silica cuprous sulfate (CDSCS) as a new and convenient heterogeneous nano catalyst is described. In this protocol, ‘click’ cycloaddition of various structurally diverse alkynes and imidoyl chlorides in the presence of CDSCS and NaHCO3 in a solution of i-PrOH/H2O (1:1, V/V) furnishes the corresponding 3,5-disubstituted isoxazoles in good to excellent yields at room temperature. CDSCS was approved as a chemically and thermally stable nano catalyst that can be recovered and reused for many consecutive trials without considerable decline in its reactivity.
A general access to isoxazoles with outstanding functional group compatibility from the readily available ynones using trimethylsilyl azide as an amino surrogate under exceptionally simple conditions is described.
Ruthenium-catalyzed oxidative coupling of vinylene carbonate with isoxazoles: access to fused anthranils
作者:Pravin Kumar、Manmohan Kapur
DOI:10.1039/d2cc01048h
日期:——
A ruthenium-catalyzedoxidative coupling of vinylene carbonate with isoxazoles has been developed to achieve the direct C–H formylmethylation of a diverse array of arylisoxazoles utilizing the isoxazole ring as the directing group. A simple manipulation of the established reaction conditions leads to the formation of fused-anthranils. Importantly, the vinylene carbonate functions as both a formylmethyl