Mechanistic Details of Asymmetric Bromocyclization with BINAP Monoxide: Identification of Chiral Proton-Bridged Bisphosphine Oxide Complex and Its Application to Parallel Kinetic Resolution.

The mechanism of our previously reported catalytic asymmetric bromocyclization reactions using 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl (BINAP) monoxide was examined in detail by the means of control experiments, NMR studies, X-ray structure analysis, and CryoSpray electrospray ionization mass spectrometry (ESI-MS) analysis. The chiral BINAP monoxide was transformed to a key catalyst precursor, proton-bridged bisphosphine oxide complex (POHOP·Br), in the presence of -bromosuccinimide (NBS) and contaminating water. The thus-formed POHOP further reacts with NBS to afford BINAP dioxide and molecular bromine (Br) simultaneously in equimolar amounts.

Enantioselective Synthesis of Nelfinavir via Asymmetric Bromocyclization of Bisallylic Amide.

We describe a concise enantioselective synthesis of the HIV-protease inhibitor nelfinavir (1) via a new route in which the key step is construction of the central optically active 1,2-amino alcohol framework via asymmetric bromocyclization of bisallylic amide with N-bromosuccinimide in the presence of a catalytic amount of ( S)-BINAP or ( S)-BINAP monoxide. The remaining alkene and bromo functionalities were used to install the requisite thioether and chiral perhydroisoquinoline units, respectively.

Desymmetrization of Bisallylic Amides through Catalytic Enantioselective Bromocyclization with BINAP Monoxide.

We report the first desymmetrization of bisallylic amides by enantioselective bromocyclization with BINAP monoxide as a catalyst. Depending upon the substitution pattern of the alkene moieties, densely functionalized, optically active oxazoline or dihydrooxazine compounds were obtained in a highly stereoselective manner. The remaining alkene moiety was subjected to various functional group manipulations to afford a diverse array of chiral molecules with multiple stereogenic centers.