Synthesis of Trisubstituted Isoxazoles by Palladium(II)-Catalyzed Cascade Cyclization–Alkenylation of 2-Alkyn-1-one <i>O</i>-Methyl Oximes
作者:Zhigang She、Dongyue Niu、Lei Chen、Maria A. Gunawan、Xhesika Shanja、William H. Hersh、Yu Chen
DOI:10.1021/jo300090k
日期:2012.4.6
palladium-catalyzed, cascade 5-endo-dig cyclization–alkenylation synthesis of isoxazoles has been developed. The addition of 1 equiv of n-Bu4NBr significantly increases the yield of the desired 4-alkenyl-3,4,5-trisubstituted isoxazoles. A variety of trisubstitutedisoxazoles are prepared in moderate to excellent yields. One example of the synthesis of a naphthoisoxazole is reported by a cascade cyclization–alkenylation-Heck
Stereospecific Suzuki, Sonogashira, and Negishi Coupling Reactions of <i>N</i>-Alkoxyimidoyl Iodides and Bromides
作者:Debra D. Dolliver、Bijay T. Bhattarai、Arjun Pandey、Megan L. Lanier、Amber S. Bordelon、Sarju Adhikari、Jordan A. Dinser、Patrick F. Flowers、Veronica S. Wills、Caroline L. Schneider、Kevin H. Shaughnessy、Jane N. Moore、Steven M. Raders、Timothy S. Snowden、Artie S. McKim、Frank R. Fronczek
DOI:10.1021/jo400179u
日期:2013.4.19
N-alkoxyimidoyl iodides is described. This reaction occurs with complete retention of the imidoyl halide geometry to give single E- or Z-isomers of diaryl oxime ethers. The Sonogashira coupling of N-alkoxyimidoyl iodides and bromides with a wide variety of terminal alkynes to afford single geometric isomers of aryl alkynyl oxime ethers has also been developed. Several of these reactions proceed through
synthesized in moderate to excellent yields from (E/Z)-alkynyl-O-methyl oximes via chlorinative cyclization. The synthesis employs the combination of N-chlorosuccinimide (NCS) and chlorotrimethylsilane (TMSCl) in nitromethane solvent where chlorine (Cl2) and hydrochloric acid (HCl) are generated in situ. In addition, the current protocol is applicable to the synthesis of 4-bromo- and 4-iodoisoxazoles when
A palladium-catalyzed carbohalogenation of olefins with alkynyl oxime ethers has been described, which provides efficient and practical access to various chlorine-containing isoxazoles. This method exhibits excellent regioselectivity, good functional group compatibility, and mild reaction conditions. The mechanistic studies suggest that the reaction proceeds via a stabilized π-benzyl palladium intermediate