gamma-halocarbanions that undergo fast intramolecular substitution of the halogen to produce substituted cyclopropanes. We found that these short-lived carbanionic intermediates can be trapped with active external electrophilic partners, such as aldehydes, to give the aldol anions. These anions then undergo rapid intramolecular substitution of chloride to produce 2,3-disubstituted tetrahydrofurans. Under the right
New reactions of γ-halocarbanions: underestimated reactive intermediates in organic synthesis
作者:M. Barbasiewicz、M. Judka、M. Makosza
DOI:10.1007/s11172-005-0043-8
日期:2004.9
Michael acceptors to give anionic adducts, which undergo intramolecular substitution to give substituted tetrahydrofurans, pyrrolidines, and cyclopentanes. This has underlain a new method for the synthesis of these valuable ring systems. We have determined the acidity of the γ-halocarbanion precursors and have shown that the halogen atoms in the γ-position relative to the carbanion center exert a significant