Enantioselective, Lewis Base Catalyzed Sulfenocyclization of Polyenes
Scott Denmark reports on the enantioselective sulfenocyclization of polyenes under Lewis base catalysis.
Polyene cyclization is one of the most general methods for constructing diverse polycyclic skeletons, such as those found in steroid and terpenoid natural products. The reaction, which finds its origins in the biosynthesis of polycyclic terpenes, is also attractive for synthetic chemistry, owing to its ability to form products with multiple rings and stereogenic centers in a non-stop process from simple, linear, achiral starting materials. Many methods for cyclization of polyenes have been developed that involve cationic, anionic, and radical intermediates. Despite the many advances that have been made in this area, catalytic, enantioselective polyene cyclizations are significantly less well developed. Recently, the group of Professor Scott Denmark at the University of Illinois (USA) described a chiral thiiranium ion induced, polyene cyclization that proceeds in good yields with high enantioselectivities under mild conditions.
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