The Regioselectivity of Addition of Organolithium Reagents to Enones and Enals: The Role of HMPA
作者:William H. Sikorski、Hans J. Reich
DOI:10.1021/ja010053w
日期:2001.7.1
addition of sulfur-substituted organolithium reagents to cyclohexenones and hexenal was studied. Low-temperature, multinuclear NMRstudies provided quantitative information about the ratio of contact (CIP) and solvent-separated (SIP) ionpairs in solutions of dithianyllithiums and phenylthiobenzyllithiums in THF-HMPA solutions. The ratio of contact and separated ionpairs was manipulated by changes in
11-Deoxydaunomycinone (2), the aglycone of a recently isolated antitumour anthracycline, is prepared using two different routes in only seven and eight steps respectively.