Stereocontrolled Syntheses of Polysubstituted 2,3-Dihydro-4H-pyran-4-ones by cyclocondensation of ?- acyloxy-ketones
作者:Wolfgang Oppolzer、In�s Rodriguez
DOI:10.1002/hlca.19930760315
日期:1993.5.12
syn-β-Acyloxy-ketones 6 and an anti-β-acyloxy-ketone 17 undergo smooth intramolecular enolate/ester condensations 6 18 and 17 19 when treated with TiCl4/EtN(i-Pr)2. Thus, tri- and tetrasubstituted cis- or trans-2,3-dihydro-4H-pyran-4-ones are easily prepared in a stereoselective manner.