Chiral Bicyclo[3.3.0]octa-2,5-dienes as Steering Ligands in Substrate-Dependent Rhodium-Catalyzed 1,4-Addition of Arylboronic Acids to Enones
作者:Sarah Helbig、Sven Sauer、Nicolai Cramer、Sabine Laschat、Angelika Baro、Wolfgang Frey
DOI:10.1002/adsc.200700232
日期:2007.10.8
The synthesis of disubstituted chiral diene ligands (3aR,6aR)- and (3aS,6aS)-10 with a pentalene backbone from the corresponding bicyclo[3.3.0]octa-1,4-diones 7 is described. The latter were accessible by enzymatic resolution of the racemic diol rac-5 and subsequent Swern oxidation. The efficiency of the ligands 10 in the rhodium-catalyzed 1,4-addition of arylboronic acids 12 to cyclic and acyclic
描述了从相应的双环[3.3.0] octa-1,4-diones 7合成具有戊烯骨架的双取代的手性二烯配体(3a R,6a R)-和(3a S,6a S)-10。后者可通过消旋外消旋二醇rac - 5的酶解和随后的Swern氧化获得。可以证明在铑催化的芳基硼酸12向环和非环烯酮11和15的1,4-加成中的配体10的效率。在环状烯酮11的情况下,对映体二苯基二烯(3aR,6a R)-和(3a S,6a S)-10a比相应的二苄基二烯配体10b更具选择性。然而,当使用无环烯酮15时,该结果相反。配体10a几乎没有活性,而二苄基二烯10b提供了对映选择性高达91%的加成产物16。