Amide-Directed Highly Enantioselective Hydrogenation of Diverse Acyclic Multisubstituted Alkenes Under Mild Conditions.

Enantioselective hydrogenation of tetrasubstituted alkenes to form 1,2-contiguous stereocenters is a particularly appealing but highly challenging transformation in asymmetric catalysis. Despite the notable progress achieved in enantioselective hydrogenation over the past decades, enantioselective hydrogenation of all-carbon tetrasubstituted alkenes containing multiple alkyl groups remains an unsolved challenge. Here, we report a rhodium-catalyzed highly diastereo- and enantioselective hydrogenation of diverse acyclic multisubstituted alkenes under mild conditions.

Rhodium-Catalyzed Highly Enantioselective Hydroboration of Acyclic Tetrasubstituted Alkenes Directed by an Amide.

Although progress has been made in enantioselective hydroboration of di- and trisubstituted alkenes over the past decades, enantioselective hydroboration of tetrasubstituted alkenes with high diastereo- and enantioselectivities continues as an unmet challenge since the 1950s due to its extremely low reactivity and the difficulties to simultaneously control the regio- and stereoselectivity of a tetrasubstituted alkene. Here, we report highly regio-, diastereo-, and enantioselective catalytic hydroboration of diverse acyclic tetrasubstituted alkenes. The delicate interplay of an electron-rich rhodium complex and coordination-assistance forms a highly adaptive catalyst that effectively overcomes the low reactivity and controls the stereoselectivity.

Coordination Assistance: A Powerful Strategy for Metal-Catalyzed Regio- and Enantioselective Hydroalkynylation of Internal Alkenes.

ConspectusAlkenes are versatile compounds that are readily available on a large scale from industry or through organic synthesis. The widespread occurrence of alkenes provides the continuous impetus for the development of catalytic asymmetric alkene hydrofunctionalizations, which enables expeditious construction of complex chiral molecules from readily available starting materials. Catalytic asymmetric hydrofunctionalization of internal alkenes presents a notable challenge, due to their low reactivity, many potential side reactions, and the simultaneous control of the regio-, diastereo-, and enantioselectivities.

Enantioselective synthesis of tertiary boronic esters through catalytic asymmetric reversed hydroboration.

Chiral tertiary boronic esters are important precursors to bioactive compounds and versatile synthetic intermediates to molecules containing quaternary stereocenters. The development of conjugate boryl addition to α,β-unsaturated amide has been hampered by the intrinsic low electrophilicity of the amide group. Here we show the catalytic asymmetric synthesis of enantioenriched tertiary boronic esters through hydroboration of β,β-disubstituted α,β-unsaturated amides.

Shot noise of spin-polarized electrons in a single-channel magnetic tunnel junctions.

Based on the free electron approximation and Egues' shot noise theory, the shot noise of spin-polarized electrons tunneling in ferromagnetic/semiconductor/ferromagnetic tunnel junctions is studied. Considering the matching of conduction band between ferromagnetic and semiconductor layers, our results show that the Fano factors of spin-polarized electrons have resonant tunneling characteristics when the semiconductor thickness and Rashba spin-orbit coupling strength are increased. When the magnetic moments in two ferromagnetic layers are parallel, with the increase of the molecular field in the ferromagnets, the Fano factor for spin-up electron decreases to zero and then increases exponentially and the Fano factor for spin-down electron is always linear.

Anti-selective [3+2] (Hetero)annulation of non-conjugated alkenes via directed nucleopalladation.

2,3-Dihydrobenzofurans and indolines are common substructures in medicines and natural products. Herein, we describe a method that enables direct access to these core structures from non-conjugated alkenyl amides and ortho-iodoanilines/phenols. Under palladium(II) catalysis this [3 + 2] heteroannulation proceeds in an anti-selective fashion and tolerates a wide variety of functional groups.

Palladium(0)-Catalyzed Directed syn-1,2-Carboboration and -Silylation: Alkene Scope, Applications in Dearomatization, and Stereocontrol by a Chiral Auxiliary.

We report the development of palladium(0)-catalyzed syn-selective 1,2-carboboration and -silylation reactions of alkenes containing cleavable directing groups. With B pin or PhMe Si-Bpin as nucleophiles and aryl/alkenyl triflates as electrophiles, a broad range of mono-, di-, tri- and tetrasubstituted alkenes are compatible in these transformations. We further describe a directed dearomative 1,2-carboboration of electron-rich heteroarenes by employing this approach.

Stereodivergent Synthesis through Catalytic Asymmetric Reversed Hydroboration.

The control of chemo-, regio-, diastereo-, and enantioselectivity is a central theme in organic synthesis. The capability to obtain the full set of stereoisomers of a molecule would significantly enhance the efficiency for the synthesis of natural product analogues and creation of chiral compound libraries for drug discovery. Despite the tremendous progress achieved in the field of asymmetric synthesis in the past decades, the precise control of both relative and absolute configurations in catalyst-controlled reactions that create multiple stereocenters remains a significant synthetic challenge.