Synthesis and utility of organoboron reagents for enantioselective synthesis.

摘要

Described herein are three distinct projects centered on the formation and use of carbon-boron bonds. In the first, the enantioselective platinum-catalyzed 1,4-diboration of trans-1,3-dienes is advanced in both selectivity and scope through the development of a novel class of electron rich chiral monodentate phosphines. Under the action of the new ligands, highly selective diboration is maintained at reduced loadings of catalyst. Secondly, enantioenriched 1,2-bis(pinacol boronates) are engaged in regioselective Suzuki-Miyaura cross-coupling with aryl and vinyl electrophiles. A tandem diboration cross-coupling sequence is successfully implemented to afford homobenzylic and homoallylic pinacol boronates directly from terminal olefins, which subsequently undergo oxidation, amination or homologation of the remaining carbon-boron bond to arrive at a range of enantioenriched products. Lastly, aryl electrophiles containing tethered allylboronate units undergo efficient intramolecular coupling in the presence of a chiral palladium catalyst to give enantioenriched carbocyclic products.