Development of Chiral Bis-hydrazone Ligands for the Enantioselective Cross-Coupling Reactions of Aryldimethylsilanolates

A palladium-catalyzed, enantioselective, aryl-aryl cross-coupling reaction using 1-naphthyldimethylsilanolates and chiral bis-hydrazone ligands has been developed. A family of glyoxal bis-hydrazone ligands containing various 2,5-diarylpyrrolidine groups was prepared to evaluate the influence of ligand structure on the rate and enantioselectivity of the cross-coupling. New synthetic routes to the 1-amino-2,5-diarylpyrrolidines were developed to enable the structure/reactivity-selectivity studies. Role reversal experiments of aryldimethylsilanolates and aryl bromides result in biaryl products with the same configuration and similar enantioselectivities implying that reductive elimination is the stereodetermining step. The origin of stereoselectivity is rationalized through computational modeling of diarylpalldium(II) complex which occurs through a conrotatory motion for the two aryl groups undergoing C-C bond formation.

Nickel-catalysed P–C bond formation via P–H/C–CN cross coupling reactions

Nickel-catalysed P–H/C–CN cross coupling reactions take place efficiently under mild reaction conditions affording the corresponding sp²C–P bonds. This transformation provides a convenient method for the preparation of both arylphosphines and arylphosphine oxides from the readily available P–H compounds and arylnitriles.

Crystal structure of (R)-2'-benz-yloxy-[1,1'-binaphthalen]-2-yl tri-fluoro-methane-sulfonate

In the title compound, C₂₈H₁₉F₃O₄S, a new 2′-benz­yloxy (R)-BINOL derivative containing a tri­fluoro­methane­sulfonate group in the 2-position, the planes of the two naphthyl ring systems (r.m.s. deviations = 0.012 and 0.019 Å) are at an angle of 73.36 (2)°, and the planes of the benzyl ring and the naphthyl ring system bound to the ether O atom are at an angle of 75.67 (4)°. In the crystal, mol­ecules are linked via C—H⋯F hydrogen bonds, forming chains propagating along [100]. The chains are linked via a weak C—F⋯π inter­action and weak π–π inter­actions [shortest inter-centroid distance = 3.9158 (12) Å], forming a three-dimensional structure. The absolute structure of the mol­ecule in the crystal was determined by resonant scattering [Flack parameter = 0.02 (6)].

Chiral phosphines in nucleophilic organocatalysis

This review discusses the tertiary phosphines possessing various chiral skeletons that have been used in asymmetric nucleophilic organocatalytic reactions, including annulations of allenes, alkynes, and Morita–Baylis–Hillman (MBH) acetates, carbonates, and ketenes with activated alkenes and imines, allylic substitutions of MBH acetates and carbonates, Michael additions, γ-umpolung additions, and acylations of alcohols.

Non-precious metals catalyze formal [4 + 2] cycloaddition reactions of 1,2-diazines and siloxyalkynes under ambient conditions

Copper(I) and nickel(0) complexes catalyze the formal [4 + 2] cycloaddition reactions of 1,2-diazines and siloxyalkynes, a reaction hitherto best catalyzed by silver salts. These catalysts based on earth abundant metals are not only competent, but the copper catalyst, in particular, promotes cycloadditions of pyrido[2,3-d]pyridazine and pyrido[3,4-d]pyridazine, enabling a new synthesis of quinoline and isoquinoline derivatives, as well as the formal [2 + 2] cycloaddition reaction of cyclohexenone with a siloxyalkyne.

Preparation of phosphines through C-P bond formation

Phosphines are an important class of ligands in the field of metal-catalysis. This has spurred the development of new routes toward functionalized phosphines. Some of the most important C–P bond formation strategies were reviewed and organized according to the hybridization of carbon in the newly formed C–P bond.