Tri(1-adamantyl)phosphine: Expanding the Boundary of Electron-Releasing Character Available to Organophosphorus Compounds

Abstract

We report here the remarkable properties of PAd3, a crystalline air-stable solid accessible through a scalable SN1 reaction. Spectroscopic data reveal that PAd3, benefiting from the polarizability inherent to large hydrocarbyl groups, exhibits unexpected electron releasing character that exceeds other alkylphosphines and falls within a range dominated by N-heterocyclic carbenes. Dramatic effects in catalysis are also enabled by PAd3 during Suzuki-Miyaura cross-coupling of chloro(hetero)arenes (40 examples) at low Pd loading, including the late-stage functionalization of commercial drugs. Exceptional space-time yields are demonstrated for the syntheses of industrial precursors to valsartan and boscalid from chloroarenes with ∼2 × 10(4) turnovers in 10 min.

Catalytic diastereo- and enantioselective additions of versatile allyl groups to N–H ketimines

“…2c); these lower e.r. might partly arise from an increase in attractive London dispersion forces between the 3,5-bis-(2,4,6-( i -Pr) 3 -phenyl)phenyl group and the substrate’s alkyl chain 45,46,47 . It is however more plausible that higher conformational mobility of the alkyl chains disrupt N→Na chelation [less optimal C NHC -Cu-C 1 -C 2 dihedral angle in I (151.3°) vs. in I (131.8°)].…”

Pyridinylidenaminophosphines: Facile Access to Highly Electron‐Rich Phosphines

“…One of the main reasons for their broad range of applications is the intriguing ease with which the steric and electronic properties of phosphines can be rationally tuned using various substituents . Although a huge variety of phosphines with diverse stereoelectronic properties have been synthesized over the last decades, the limit of electron‐donating character accessible to phosphines has been defined by alkylphosphines for more than half a century and modest advancement in this respect has been achieved using electropositive plumbyl, carboranyl, N‐heterocyclic boryl, anionic boratabenzene, or adamantyl substituents.…”

Tris(imidazolin‐2‐ylidenamino)phosphine: A Crystalline Phosphorus(III) Superbase That Splits Carbon Dioxide

“…A quantitative description of the phosphine's stereoelectronic properties is most commonly provided by the Tolman electronic parameter (TEP) and cone angle . The classical boundaries of the electron‐releasing character of organophosphines have been recently expanded by Alcarazo's cationic phosphines that act as very strong π‐acceptor ligands, while Carrow et al showed that tri(1‐adamantyl)phosphine is significantly more donating than P( t Bu) 3 (Figure ) …”