When Chirality Meets “Buchwald‐Type” Phosphines: Synthesis and Evaluation in Frustrated Lewis Pair‐, Lewis Base‐ and Palladium‐Promoted Asymmetric Catalysis

Abstract

We describe the synthesis of axially chiral “Buchwald ligand”‐like biphenylphosphines in highly enantioenriched form. These monodentate phosphines, biphenyl analogues of Hayashi's MOP ligands, were evaluated in phosphine‐promoted organocatalysis and in hydrosilylations catalyzed by palladium or by frustrated Lewis pairs. As expected, the title phosphines appeared best suited for transition metal catalysis where they provided higher asymmetric induction.

Stereoselectivity Switch in the Trapping of Polar Organometallics with Andersen’s Reagent—Access to Highly Stereoenriched Transformable Biphenyls

“…Either way, in our study (Scheme b) as well as in Clayden’s and Knochel’s, the trapping of the biaryllithium furnished in all cases a ca. 1:1 mixture of diastereomers. , In fact, the trapping of configurationally stable, chiral racemic, polar carbometalated species with Andersen’s reagent seems to proceed with a very low level of resolution in all cases, regardless of the nature of the chirality element (central, axial, planar) on the nucleophile used (Scheme a), − which contrasts with the otherwise usually excellent stereoinduction achieved with the sulfinyl group . In the present paper, we describe the unusual kinetic resolution of biphenyls by means of Andersen’s reagent upon treatment of 2-iodobiphenyls with isopropylmagnesium chloride (Scheme c).…”

“…Axially chiral biaryls have proven to be highly important motifs in natural compounds and in asymmetric synthesis; their preparation is a contemporary topic of research, and several strategies have been followed, among which the resolution of a pre-existing biaryl . In 2012, we reported on a modular access to 2,2′,6-trisubstituted biphenyls, based on the deracemization or desymmetrization of, respectively, racemic or meso -2,2′,6-trihalobiphenyls ( 1a and 1b , Scheme b) . This strategy was inspired by the work of Clayden on binaphthyls and of Knochel on naphthylquinolines and relied on the trapping of Andersen’s reagent ( 2 ) by biphenyllithium intermediates, separation of atropo-diastereoisomers by crystallization, and subsequent functionalization by sulfoxide/metal exchange.…”

Construction of Bulky Ligand Libraries by Ru(II)-Catalyzed P(III)-Assisted ortho-C–H Secondary Alkylation

“…With this strategy, a series of general and efficient phosphine ligands, such as XPhos, BrettPhos, and RockPhos have been designed by Buchwald and others . At present, synthesis of alkyl substituted phosphines mainly relies on the traditional multistep synthetic route, which survived under harsh conditions, poor tolerance of functional groups, and low efficiency, thus limiting the efficient synthesis and development of new phosphines.…”

Crystal structure of 1-(4-hydroxybenzoyl)-2,7-dimethoxynaphthalene: Contribution of classical and non-classical hydrogen bonding interactions to the molecular packing structure

“…Non-coplanarly accumulated-aromatic-rings containing compounds such as aromatic ring assembly of binaphthyl and biphenyl have received much attention from wide-range of organic chemists and material chemists as useful molecular building block [1][2][3][4]. The spatial organizations of aromatic rings in these molecules are fixed as non-coplanar accumulation mode leading to expression of enantioselectivity and regioselectivity in organic reaction.…”