Synthesis of Organoboronic Acids and Applications in Asymmetric Organocatalysis

Abstract: Allyl- and allenylboronic acids are valuable reagents in organic synthesis due to their configurational stability and high reactivity. Few allyl- and allenylboronates are commercially available. Therefore, both the preparation and synthetic application of these organoboronic acids are subjects of study. A copper-catalyzed method for the synthesis of tetrasubstituted allenylboronic acids is presented in this thesis. Several enantioselective applications of these allenylboronic acids are presented, including the synthesis of chiral α-amino acid derivatives. Applications of γ,γ-disubstituted allylboronic acids in asymmetric organocatalysis are also presented in this thesis. Varying the E-Z geometry of the allylboron reagents allowed for stereodivergent synthesis of products bearing up to three stereocenters. A common element in the asymmetric methodologies described in this thesis is the application of BINOL-type organocatalysts. The most notable example is the methodology developed for the preparation of α-chiral allylboronic acids via asymmetric homologation of olefinic boronic acids. The resulting chiral boronic acids are of high synthetic interest, which is demonstrated by the wide variety of synthetic applications including allylboration, oxidation, and a purification sequence leading to isolated α-chiral allylboronic acids.