作者:Faiz Khan、K. Krishnakumar、Ch. Sudheer
DOI:10.1055/s-2007-965948
日期:2007.4
A short and efficient route to δ-lactone-fused cyclopentanoids starting from the easily accessible Diels-Alder adducts between homoallylic alcohol acetates and 1,2,3,4-tetrachloro-5,5-dimethoxycyclopenta-1,3-diene is reported. Since homoallyl alcohols were derived from the corresponding aldehydes RCHO (R = alkyl, aryl) through allyl metal addition, the methodology is broad in scope with regard to the choice of R group. The initially formed 1:1 diastereomeric mixture of adducts were subjected to ruthenium-catalyzed oxidation followed by acid-mediated hydrolysis of the acetate groups to obtain the hemiacetals 6a-e. Alkaline H2O2-mediated cleavage of the hemiacetals led, after esterification with diazomethane, to a chromatographically separable diastereomeric mixture of 7 and 8 in high overall yield (54-68%).
报告了一种简短而高效的路线,可以从容易获得的同烯丙醇醋酸酯与1,2,3,4-四氯-5,5-二甲氧基环戊烯-1,3-二烯之间的Diels-Alder加合物出发,合成δ-内酯融合的环戊烷族化合物。由于同烯丙醇是通过烯丙金属的加成反应从相应的醛RCHO(R = 烷基、芳基)中衍生而来,因此该方法在R基团的选择上具有广泛的适用性。最初形成的1:1的抗异构体混合物经过钌催化氧化后,进而通过酸介导的醋酸基水解获得半醚6a-e。碱性过氧化氢对半醚的裂解,在与氮甲烷酯化后,得到了可通过色谱分离的抗异构体混合物7和8,整体产率高达54-68%。