Diastereoselective Friedel–Crafts Alkylation of Hydronaphthalenes

An efficient and versatile synthesis of chiral tetralins has been developed using both inter- and intramolecular Friedel–Crafts alkylation as a key step. The readily available hydronaphthalene substrates were prepared via a highly enantioselective metal-catalyzed ring opening of <i>meso</i>-oxabicyclic alkenes followed by hydrogenation. A wide variety of complex tetracyclic compounds have been isolated with high levels of regio-, diastereo-, and enantioselectivity

Boroalkyl Group Migration Provides a Versatile Entry into α-Aminoboronic Acid Derivatives

A reaction exemplifying migration of boron-substituted carbon is described. We show that α-boroalkyl groups of transient boroalkyl acyl azide intermediates readily migrate from carbon to nitrogen. This process allows access to a new class of stable molecules, α-boryl isocyanates, from α-borylcarboxylic acid precursors. The methodology facilitates synthesis of a wide range of α-aminoboronic acid derivatives, including α,α-disubstituted analogues

Boron-Containing Enamine and Enamide Linchpins in the Synthesis of Nitrogen Heterocycles

The use of α-boryl enamine and enamide linchpins in the synthesis of nitrogen heterocycles has been demonstrated. Boryl enamines provide ready access to the corresponding α-halo aldehydes, which undergo regioselective annulation to form borylated thiazoles. A condensation/amidation sequence converts α-boryl aldehydes into stable α-boryl enamides without concomitant C → N migration. We also show that palladium-catalyzed cyclization of α-boryl enamides leads to synthetically versatile isoindolones. These molecules can be subsequently used to access polycyclic scaffolds