New Methods for Stereoselective Incorporation of Boron into Molecules Utilizing 1,1-Organodiboronate Esters

I. Enantio- and Diastereoselective 1,2-Additions of 1,1-Diborylalkanes to alpha-Ketoesters An enantio- and diastereoselective addition of 1,1-diborylalkanes to alpha-ketoesters is reported. The reaction is catalyzed by a copper-phosphoramidite catalyst system and yields products in up to 70% yield, 99:1 er and >20:1 dr after oxidation to the corresponding diol. The utility of the products is illustrated through functionalizations including homologation, cross-metathesis, and tetrahydropyran synthesis. II. Stereoselective 3-Component Bis-Electrophile Couplings of 1,1-Diborylalkanes A stereoselective tandem epoxide ring-opening/allylation reaction facilitated by a copper catalyst is reported. The reaction is tolerant of alkyl and aryl epoxides in good yield (up to 99%) and diastereoselectivity (up to >20:1). The application of this technique to the synthesis of polyol motifs is explored. Cross coupling, amination, and alkene functionalization reactions illustrate the versatility of the products. III. Synthesis of Stereodefined Alkenyl Boronates from Epoxides and Diborylmethane through Pd-Catalyzed Dehydroboration The palladium catalyzed synthesis of alkenyl boronate esters from epoxides and diborylmethane via a dehydroboration process is reported. Products are obtained in up to 75% yield as single olefin isomer. The substrate scope includes alkyl, aryl, and complex steroid derived molecules. The products are further functionalized through cross coupling and cycloproponation procedures.Doctor of Philosoph