Activation of gem-diborylalkanes and alkenes to emcopass selective C-C bond forming reactions

Identifier:  TDX:4121

Handle: https://hdl.handle.net/20.500.11797/TDX4121

Authors:  Salvadó Ruiz, Oriol

Abstract:
Organoboron chemistry has been widely studied over the past decades due to its importance in organic synthesis, becoming a highly efficient tool since organoboron compounds can be transformed into a wide range of functional groups. Recently, gem-diboron compound have emerged as alternative bifunctional reagents for selective C-C bond formation. The present thesis contributes to the field with new methodologies that allow the synthesis of gem-diborylalkenes, as well as, conducting novel activation modes and reactivity trends towards the formation of unprecedented organoboron compounds. In Chapter 3, the boron-Wittig olefination reaction between aromatic or aliphatic aldehydes and gem-diborylsilylmethide lithium salts has been successfully conducted. The afforded (E)-stereoisomeric trisubstituted 1,1-silylborylalkenes have been prepared for the first time in this thesis, complementing the alternative existing methodologies to synthesise the analogous Z-1,1-silylborylalkenes. In Chapter 4, regioselective ring-opening of vinyl aziridines with diborylalkyl lithium salts has been established. The afforded products maintained the two boryl moieties except for reactions involving aryl-substituted gem-diborylalkanes which are prone to develop protodeborylation. All the products synthesised in this Chapter have been prepared for the first time in the present work. In Chapter 5, two new synthetic strategies have been efficiently developed to prepare 1,1-diborylalkenes. Condensation of aldehydes with triborylmethide lithium salt, allows the formation of gem-diborylalkenes.