Synthesis of medium-sized lactones from siloxy alkynes via ring expansion
作者:An Wu、Wanxiang Zhao、Jianwei Sun
DOI:10.1016/j.tet.2020.131163
日期:2020.12
topic in organic synthesis due to the disfavored kinetic and thermodynamic features. Herein we detail an efficient intermolecular process using siloxyalkynes as substrates and oxetene ring expansion as the key strategy. With extension to a new silyl-masked alkyne, this reaction now features a broad scope, high efficiency, and mild conditions.
selective cleavage of acetal-derived alkylsilyl peroxides, followed by the formation of a carbon-carbon bond is reported. The reaction proceeds under mild reaction conditions and exhibits a broad substrate scope with respect to the acetal moiety and the carbon electrophile. Mechanistic studies suggest that the present reaction proceeds through a free-radical process involving carbon radicals generated
Five-, four-, and three-membered carbocyclic rings from 2-deoxyribose by intramolecular nucleophilic displacement reaction
作者:Karsten Krohn、Guido Boerner
DOI:10.1021/jo00021a015
日期:1991.10
1,3-Dithianes such as 4, 9, 11, 13, and 19 derived from 2-deoxy-D-ribose (1) undergo intramolecular displacement reactions to give three-, four-, and five-membered carbocyclic rings (5, 10, 12, 15, and 20). Cyclopropanes are favored over the cyclobutanes when starting from the epoxides 9 or 11. Treatment of the tosylate 19 gives only a small yield of the corresponding cyclobutane 20, the major product being the ketone 21.