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Reported here is a straightforward process in which a cyclic (alkyl)(amino)carbene/Rh catalyst system facilitates the preferential addition of hydrogen to the substitution sites of difluoromethylated and trifluoromethylated arenes and heteroarenes, leading to dearomative reduction. This strategy enables the diastereoselective synthesis of cis‐difluoromethylated and cis‐trifluoromethylated cycloalkanes and saturated heterocycles, and even allows formation of all‐cis multi‐trifluoromethylated cyclic products with a defined equatorial orientation of the di‐ and trifluoromethyl groups. Deuterium‐labeling studies indicate that hydrogen preferentially attacks the substitution sites of planar arenes, resulting in dearomatization, possibly with heterogeneous Rh as the reactive species, followed by either reversible or irreversible hydrogen addition to the nonsubstitution sites. [ABSTRACT FROM AUTHOR]

Terminal alkynes react with aromatic sulfonyl chlorides in the presence of an iron(II) catalyst and a phosphine ligand to give (E)-β-chlorovinylsulfones with 100% regio- and stereoselectivity. Various functional groups, such as chloride, bromide, iodide, nitro, ketone, and aldehyde, are tolerated under the reaction conditions. Addition of tosyl chloride to a 1,6-enyne followed by radical 5-exo-trigcyclization gave an exocyclic alkenylsulfone. [ABSTRACT FROM AUTHOR]

Itis reported that a nickel/phosphine catalyst allows the C–Hallylation to occur effectively with the allyl site selectivity predominantlygoverned by steric effects. This reaction provides a facile and predictableroute for the selective preparation of linear allylarenes from readilyavailable benzamides and allyl phosphates. [ABSTRACT FROM AUTHOR]

Wereport here that mono-N-protected amino acids (MPAAs), an importantenvironmentally compatible structural motif, enable acceleration ofPd(II)-catalyzed dehydrogenative Heck reactions between pyridinesand electron-deficient arenes with simple alkenes, leading to diverselyfunctionalized C3- or meta-selective alkenylatedpyridines and benzenes via non-chelate-assisted C–H activation.A comprehensive theoretical study by DFT calculations discloses thatthe amino scaffold of the MPAA ligand facilely converts to an X-typeligand by an initial N–H activation, resulting in a relativelylow activation barrier for the C–H cleavage of pyridine. Thena property reversal of the amino group from X-type to L-type ligandallows the alkene substitution to take place smoothly, while the carboxylgroup enables the formation of an intramolecular hydrogen bond, significantlydecreasing the activation barrier for the carbopalladation. The resultsof calculations and the kinetic isotopic effect measurement supporta rate-limiting C–H activation by a mechanism involving a concertedmetalation/deprotonation pathway, with an endothermicity of 31.0 kcal/molin the process. [ABSTRACT FROM AUTHOR]