ABSTRACT
Two methods are reported for the 1,2- and 1,1-arylboration of α-methyl vinyl arenes. In the case of 1,2-arylboration, the formation of a quaternary center occurred through a rare cross-coupling reaction of a tertiary organometallic complex. 1,1-Arylboration was enabled by catalyst optimization and occurred through a ß-hydride elimination/reinsertion cascade. Enantioselective variants of both processes are presented as well as mechanistic investigations.
Subject(s)
Alkenes/chemistry , Boron Compounds/chemical synthesis , Copper/chemistry , Palladium/chemistry , Boron Compounds/chemistry , Catalysis , Molecular StructureABSTRACT
A Ni-catalyzed method for arylboration is disclosed. The method allows for highly stereoselective arylboration of unactivated alkenes. The reactions utilize a simple Ni-catalyst and work with a broad range of alkenes and aryl bromides. The products represent useful intermediates for chemical synthesis due to the versatility of the C-B bond. Preliminary mechanistic details of the method are also disclosed.
Subject(s)
Alkenes/chemistry , Boron Compounds/chemical synthesis , Nickel/chemistry , Boron Compounds/chemistry , Catalysis , Molecular Structure , StereoisomerismABSTRACT
A method for the catalytic enantioselective arylboration of alkenylarenes is disclosed. The reaction leads to the formation of 1,1-diarylalkanes that also incorporate an additional pinacol boronic ester which can be easily transformed to a variety of groups. The products are formed with excellent diastereoselectivities and enantioselectivities.
Subject(s)
Alkenes/chemistry , Boron Compounds/chemical synthesis , Copper/chemistry , Organometallic Compounds/chemistry , Palladium/chemistry , Boron Compounds/chemistry , Catalysis , Molecular Conformation , StereoisomerismABSTRACT
A method for the diastereoselective carboboration of 1,2-disubstituted styrenes with aryl/vinyl bromides and (Bpin)2 is reported. High diastereoselectivities and yields are observed for the formation of either diastereomer of the product from a single alkene isomer. These reactions provide access to a diverse range of structures from simple starting materials.
ABSTRACT
A synergistic Pd/Cu system for the coupling of alkenes, (Bpin)2 (pin = pinacolate), and aryl/vinyl bromides is disclosed. This method allows for the catalytic generation of secondary Csp(3)-Cu nucleophiles in situ and subsequent Pd-catalyzed cross-coupling.
ABSTRACT
A method for amide-directed Ni-catalyzed diastereoselective arylboration of cyclopentenes is disclosed. The reaction allows for the synthesis of sterically congested cyclopentane scaffolds that contain an easily derivatized boronic ester and amide functional handles. The nature of the amide directing group and its influence on the reaction outcome are investigated and ultimately reflect a predictably selective reaction based on the solvent and base counterion.