Here, we report a chromium-catalyzed activation of acyl C−O bonds with magnesium for amidation of esters with nitroarenes. Low-cost chromium(III) chloride shows high reactivity in promoting amidation by using magnesium as reductant and chlorotrimethylsilane as additive. It provides a step-economic strategy to the synthesis of centrally important amide motifs using inexpensive and airstable nitroarenes as amino sources.

We herein report the hydrogenation of substituted aryl-and heteroaryl boronate esters for the selective synthesis of cis-substituted borylated cycloalkanes and saturated heterocycles.Acyclic (alkyl)(amino)carbene-ligated rhodium complex with two dimethyl groups at the ortho-alkyl scaffold of the carbene showed high reactivity in promoting the hydrogenation, therebye nabling the hydrogenation of (hetero)arenes with retention of the synthetically valuable boronate group. This process constitutes ac lean, atom-economic,a swell as chemo-and stereoselective route for the generation of cisconfigured, diversely substituted borylated cycloalkanes and saturated heterocycles that are usually elusive and difficult to prepare.

Reported here is astraightforwardprocess in which ac yclic (alkyl)(amino)carbene/Rh catalyst system facilitates the preferential addition of hydrogen to the substitution sites of difluoromethylated and trifluoromethylated arenes and heteroarenes,l eading to dearomative reduction. This strategy enables the diastereoselective synthesis of cis-difluoromethylated and cis-trifluoromethylated cycloalkanes and saturated heterocycles,a nd even allows formation of all-cis multitrifluoromethylated cyclic products with ad efined equatorial orientation of the di-and trifluoromethyl groups.D euteriumlabeling studies indicate that hydrogen preferentially attacks the substitution sites of planar arenes,r esulting in dearomatization, possibly with heterogeneous Rh as the reactive species, followed by either reversible or irreversible hydrogen addition to the nonsubstitution sites.

Deoxygenative cross-coupling between unactivated C–O and unsaturated CO electrophiles remains an unsolved challenge in synthetic chemistry. Here, we report the deoxygenative cross-coupling of C–O/CO electrophiles by reaction of unactivated aryl esters with unsaturated amides, enabled by chromium catalysis. Inexpensive and simple CrCl3 salt combined with bipyridine ligand, magnesium reductant, and chlorosilane, shows high reactivity in promoting the deoxygenative coupling between C–O and CO bonds involving hydrogen transfer. This reaction provides a strategy to form pharmaceutically interesting diarylmethylated amines, by forging C­(sp2)–C­(sp3) bonds with impeding the competing ester homocoupling and carbonyl reduction that usually occur under reductive conditions. Mechanistic studies based on high-resolution mass spectrometry analysis and deuterium-labeling experiments indicate that cleavage of ester C–O bonds by Cr and subsequent silylation leads to the formation of arylated silachromate, which regioselectively adds to carbonyls of amides through reductive elimination and deoxygenative hydrogen transfer, resulting in the reductive cross-coupling of C­(aryl)–O and C­(amide)O electrophiles.

The hydrogenation of alkynes allows the synthesis of olefins, which are important feedstock for the materials, pharmaceutical, and petrochemical industry. Thus, methods that enable this transformation via low-cost metal catalysis are desirable. However, achieving stereochemical control in this reaction is a long-standing challenge. Here, we report on the chromium-catalyzed E- and Z-selective olefin synthesis via hydrogenation of alkynes, controlled by two carbene ligands. A cyclic (alkyl)(amino)carbene ligand that contains a phosphino anchor enables the hydrogenation of alkynes in a trans-addition manner, selectively forming E-olefins. With an imino anchor-incorporated carbene ligand, the stereoselectivity can be switched, giving mainly Z-isomers. This ligand-enabled geometrical stereoinversion strategy by one metal catalysis overrides common methods in control of the E- and Z-selectivity with two different metal catalysis, allowing for highly efficient and on-demand access to both E- and Z-olefins in a stereo-complementary fashion. Mechanistic studies indicate that the different steric effect between these two carbene ligands may mainly dominate the selective forming E- or Z-olefins in control of the stereochemistry.