Functionalized 4-Carboxy- and 4-Keto-2,3-dihydropyrroles via Ni(II)-Catalyzed Nucleophilic Amine Ring-Opening Cyclizations of Cyclopropanes
作者:M. Cynthia Martin、Dadasaheb V. Patil、Stefan France
DOI:10.1021/jo5001059
日期:2014.4.4
is reported using Ni(ClO4)2·6H2O as a Lewis acid catalyst for nucleophilic amine ring-opening cyclizations of donor–acceptor (D–A) cyclopropanes. This methodology provided good to excellent yields of functionalized 2,3-dihydropyrroles under milder reaction conditions than previously reported and is amenable to a variety of D–A cyclopropanes and primary amines.
The asymmetricring‐opening/cyclization of cyclopropyl ketones with primary amine nucleophiles was catalyzed by a chiral N,N′‐dioxide/scandium(III) complex through a kinetic resolution process. A broad range of cyclopropyl ketones and primary amines are suitable substrates of this reaction. The corresponding products were afforded in excellent enantioselectivities and yields (up to 97 % ee and 98 %
An organocatalytic Cloke–Wilson rearrangement of cyclopropyl ketones to 2,3-dihydrofurans is exploited utilizing the homoconjugate addition process. With 1,4-diazabicyclo[2.2.2]octane as the catalyst, the rearrangement in DMSO at 120 °C proceeded in generally high yields, exclusive regioselectivity, and a broad substrate scope. An examination of the mechanism including stereochemical analysis and intermediate
Dimethyl-α-styrylsulphonium bromide as a reaction intermediate
作者:Yuan L. Chow、Bert H. Bakker、Kiyoshi Iwai
DOI:10.1039/c39800000521
日期:——
The addition product of styrene, bromine, and dimethyl sulphide was treated with bases to give the dimethyl-α-styrylsulphonium ion which reacted rapidly with various nucleophiles and also underwent slower base-catalysed rearrangement.
A gold (I)‐catalyzed reaction of enyne‐ethers to rapidly construct oxa‐bridged compounds via a tandem 1,2‐acyloxy migration/intramolecular oxonium formation/1,2‐rearrangement process was reported. The reaction was shown to be robust with a wide range of substitution patterns tolerated to provide the corresponding oxygen‐containing bridged products in good to excellent yields.