Dispiroketals in synthesis (part 10): Further reactions of dispoke protected lactate and glycolate enolates
                                
                                    
                                        作者:Geert-Jan Boons、Robert Downham、Kun Soo Kim、Steven V. Ley、Martin Woods                                    
                                    
                                        DOI:10.1016/s0040-4020(01)85241-8
                                    
                                    
                                        日期:1994.1
                                    
                                    alpha-Hydroxy acids have been reacted with bis-dihydropyrans to give dispiroketal adducts (1,8,13,16-tetraoxadispiro[5.0.5.4]-hexadecan-14-ones). The enolates derived from these compound undergo reaction with electrophiles with generally high levels of diastereoselectivity. Subsequent deprotection of these compounds gives alpha-hydroxy esters of high enantiomeric excess.