A Practical Route to Enantiopure, Highly Functionalized Seven-Membered Carbocycles and Tetrahydrofurans: Concise Synthesis of (+)-Nemorensic Acid
作者:Fernando López、Luis Castedo、José L. Mascareñas
DOI:10.1002/1521-3765(20020215)8:4<884::aid-chem884>3.0.co;2-q
日期:2002.2.15
those obtained from the sulfinyl precursors. Cleavage of the oxa-bridge on the desulfurated adducts yields highly functionalized seven-membered carbocyclic derivatives in enantiopure form. Alternative cleavage of the seven-membered carbocycle provides enantiomerically enriched tetrahydrofurans. We have exploited this reaction pathway for the synthesis of the naturally occurring enantiomer of nemorensic
高度非对映选择性的热[5C + 2C]分子内吡喃-烯烃环加成反应可通过在烯烃的合适位置引入同手性对甲苯磺酰基进行。所得的加合物可以容易地脱硫,以得到光学活性的8-氧杂双环[3.2.1]辛烷衍生物。有趣的是,从亚磺酰基转变为磺酰亚胺基可允许逆转非对映选择性的方向,从而产生与由亚磺酰基前体获得的对映体的氧杂桥碳环系统。在脱硫的加合物上裂解氧杂桥,得到对映纯形式的高度官能化的七元碳环衍生物。七元碳环的替代裂解提供了对映体富集的四氢呋喃。