Nickel-catalyzed reductive arylation of activated alkynes with aryl iodides.

The direct, regioselective, and stereoselective arylation of activated alkynes with aryl iodides using a nickel catalyst and manganese reductant is described. The reaction conditions are mild (40 °C in MeOH, no acid or base) and an intermediate organomanganese reagent is unlikely. Functional groups tolerated include halides and pseudohalides, free and protected anilines, and a benzyl alcohol. Other activated alkynes including an amide and a ketone also reacted to form arylated products in good yields.

Crystal structures of (R S)-N-[(1R,2S)-2-benz-yloxy-1-(2,6-di-methyl-phen-yl)prop-yl]-2-methyl-propane-2-sulfinamide and (R S)-N-[(1S,2R)-2-benz-yloxy-1-(2,4,6-tri-methyl-phen-yl)prop-yl]-2-methyl-propane-2-sulfinamide: two related protected 1,2-amino alcohols.

The title compounds, C22H31NO2S, (1), and C23H33NO2S, (2), are related protected 1,2-amino alcohols. They differ in the substituents on the benzene ring, viz. 2,6-di-methyl-phenyl in (1) and 2,4,6-tri-methyl-phenyl in (2). The plane of the phenyl ring is inclined to that of the benzene ring by 28.52 (7)° in (1) and by 44.65 (19)° in (2). In the crystal of (1), N-H⋯O=S and C-H⋯O=S hydrogen bonds link mol-ecules, forming chains along [100], while in (2), similar hydrogen bonds link mol-ecules into chains along [010]. The absolute structures of both compounds were determined by resonance scattering.

Bis{(R)-N-[(R)-2-benz-yloxy-1-(4-tert-butyl-phen-yl)eth-yl]-2-methyl-propane-2-sulfinamide} monohydrate.

The asymmetric unit of the title compound, 2C23H33NO2S·H2O, contains one organic mol-ecule in a general position and one co-crystallized water mol-ecule on a crystallographic twofold axis. Each water mol-ecule serves as a hydrogen-bond donor to a pair of S=O acceptors on symmetry-related mol-ecules. Thus, each trio of mol-ecules forms one title formula unit. These groupings are further connected along [010] via weak non-classical C-H⋯O hydrogen bonds.

Nickel-catalyzed reductive conjugate addition to enones via allylnickel intermediates.

An alternative method to copper-catalyzed conjugate addition followed by enolate silylation for the synthesis of ß-disubstituted silyl enol ether products (R(1)(R(2))HCCH═C(OSiR(4)(3))R(3)) is presented. This method uses haloarenes instead of nucleophilic aryl reagents. Nickel ligated to either neocuproine or bipyridine couples an α,ß-unsaturated ketone or aldehyde (R(2)HC═CHC(O)R(3)) with an organic halide (R(1)-X) in the presence of a trialkylchlorosilane reagent (Cl-SiR(4)(3)). Reactions are assembled on the benchtop and tolerate a variety of functional groups (aldehyde, ketone, nitrile, sulfone, pentafluorosulfur, and N-aryltrifluoroacetamide), electron-rich iodoarenes, and electron-poor haloarenes. Mechanistic studies have confirmed the first example of a catalytic reductive conjugate addition of organic halides that proceeds via an allylnickel intermediate. Selectivity is attributed to (1) rapid, selective reaction of LNi(0) with chlorotriethylsilane and enone in the presence of other organic electrophiles, and (2) minimization of enone dimerization by ligand steric effects.