Regio- and stereoselective Ni-catalyzed 1,4-hydroboration and diboration of 1,3-dienes

Abstract

Detailed within this dissertation are the developments of novel hydroboration and diboration methodologies to access allylboron reagents and efforts towards the application of these methods in the total synthesis of discodermolide. Chapter 1 describes the development of Ni-catalyzed 1,4-hydroboration of 1,3-dienes with pinacolborane. This method provides synthetically useful allylboron intermediates which can be oxidized to stereodefined (Z)-allylic alcohols or used in stereoselective carbonyl addition reactions. Chapter 2 details the development of Ni-catalyzed 1,4-diboration of 1,3-dienes with bis(pinacolato)diboron. This reaction broadens the scope of 1,4-diboration reactions by including internal and sterically hindered dienes, and proceeds with high 1,4- and (Z)-selectivity. The intermediate allylborons can be oxidized to stereodefined 1,4-diols. Chapter 3 describes the development of diastereoselective Ni-catalyzed 1,4-hydroboration of chiral 1,3-dienols. The reaction provides syn-propionate homoallylic alcohols with stereodefined trisubstituted allylborons for the synthesis of polyketide structures. This methodology, among others, was applied towards the total synthesis of discodermolide.