Regioselective Nickel-Catalyzed Reductive Couplings of Enones and Allenes

No AbstractPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78305/1/anie_201004740_sm_miscellaneous_information.pd

A Stereodivergent Approach to (−)-α-Kainic Acid and (+)-α-Allokainic Acid Utilizing the Complementarity of Alkyne and Allene Cyclizations

A formal synthesis of (+)-α-allokainic acid and a total synthesis of (−)-α-kainic acid were carried out using a short, efficient, and highly stereoselective approach. From an alkyne precursor, a nickel-catalyzed cyclization and a palladium-catalyzed rearrangement were utilized in the synthesis of (+)-α-allokainic acid. From an allene precursor, a nickel-catalyzed cyclization was utilized in the synthesis of (−)-α-kainic acid. The allene cyclization used in the latter sequence was the first example of a metal-catalyzed cyclization of this type

Total Syntheses of Isodomoic Acids G and H: An Exercise in Tetrasubstituted Alkene Synthesis

A unified approach to the pyrrolidine triacid natural products isodomoic acids G and H has been developed. Total syntheses of both natural products were completed, and determination of the correct stereostructure of isodomoic acid G was established by comparing 5′-(R) and 5′-(S) isomers to a sample of authentic material. A nickel-catalyzed cyclization constructs the pyrrolidine ring while simultaneously establishing either the E or Z stereochemistry of an exocyclic tetrasubstituted alkene. Stereoselective assembly of both the E- and Z-alkenes of the natural products is made possible by a predictable strategy that alters the timing of substituent introduction to control alkene stereochemistry