The title procedure is investigated for various educts bearing different ligands at the amide nitrogen.

In this paper, we report 4-amino-2,1,3-benzothiadiazole (ABTD) as a new bidentate directing group for the Pd(II)-catalyzed sp/sp C-H activation/functionalization of various aliphatic/alicyclic/aromatic carboxamide systems. The Pd(II)-catalyzed, ABTD-directed sp C-H arylation/acetoxylation of aliphatic- and alicyclic carboxamides afforded the corresponding β-C-H arylated/acetoxylated carboxamides. The Pd(II)-catalyzed, ABTD-directed sp C-H arylation of cyclobutanecarboxamide with different aryl iodides afforded the corresponding bis β-C-H arylated cyclobutanecarboxamides having all-cis stereochemistry with a high degree of stereocontrol. The Pd(II)-catalyzed, ABTD-directed arylation/benzylation/acetoxylation/alkoxylation of ortho C(sp)-H bonds of various benzamides afforded the corresponding ortho C-H arylated/benzylated/oxygenated benzamides. The observed regio- and stereoselectivity in the Pd(II)-catalyzed, ABTD-directed arylation/benzylation of aliphatic/alicyclic carboxamides and benzamides were ascertained from the X-ray structures of representative compounds 5g (bis-β-C(sp)-H arylated cyclobutanecarboxamide) and 7f (ortho C(sp)-H arylated benzamide). A brief description on the efficiency, scope, and limitations of bidentate directing group ABTD is reported.

An auxiliary-enabled and Pd(OAc)2-catalyzed direct arylation of C(sp(3))-H bonds of cyclopropanes and production of di- and trisubstituted cyclopropanecarboxamides having contiguous stereocenters are reported. The installation of aryl groups on cyclopropanecarboxamides led to the assembling of novel mono- and di- aryl-N-(quinolin-8-yl)cyclopropanecarboxamide scaffolds and mono- and di- aryl-N-(2-(methylthio)phenyl)cyclopropanecarboxamides. The stereochemistry of products was unequivocally assigned from the X-ray structures of key compounds.

An auxiliary-aided Pd-catalyzed highly diastereoselective double C-H activation and direct bis-arylation of methylene C(sp(3))-H bonds of cyclobutanecarboxamides and the syntheses of several novel trisubstituted cyclobutanecarboxamide scaffolds having an all-cis stereochemistry are reported. Extensive screening of various auxiliaries and reaction conditions was performed to firmly establish the optimized reaction conditions required for effecting the mono- or double C-H arylation of cyclobutanecarboxamides. The auxiliary-attached cyclobutanecarboxamides 15a, 15g, and 15h, prepared from the auxiliaries such as, 8-aminoquinoline, 2-(methylthio)aniline, and N',N'-dimethylethane-1,2-diamine were found to undergo an efficient direct bis-arylation. The Pd-catalyzed arylation reaction of N-(quinolin-8-yl)cyclobutanecarboxamide 15a with one equivalent or more of aryl iodides, afforded the corresponding bis-arylated cyclobutanecarboxamides 16a-y. Nevertheless, the Pd-catalyzed arylation of 15a with just 0.5 equiv of the aryl iodides 13a, 13b, 13e, and 13m, selectively gave the corresponding monoarylated cyclobutanecarboxamides 17a-17d. The Pd-catalyzed arylation of 15g or 15h with one equivalent or more of aryl iodides afforded the bis-arylated cyclobutanecarboxamides 19a-19c and 21a-21m, respectively. However, the Pd-catalyzed arylations of compounds 15g or 15h with just 0.5 equiv of aryl iodides were ineffective. The stereochemistry of compounds obtained in this work was unambiguously assigned from the X-ray structures of representative products.

We report the Pd(II)-catalyzed, bidentate directing group (BDG)-assisted arylation and successive arylation/intramolecular amidation of γ-C(sp)-H bonds. The Pd(II)-catalyzed BDG-assisted C-H activation and functionalization of the β-C(sp)-H bonds of carboxylic acids are well documented, but only a few reports are available that deal with the BDG-directed functionalization of the γ-C(sp)-H bonds. Various 3-methylthiophene/furan-2-carboxamides (1a-e) were derived from their corresponding carboxylic acids and bidentate directing groups. These compounds were then used as substrates to investigate the arylation and successive arylation/intramolecular amidation of the γ-C(sp)-H bonds. The γ-C(sp)-H arylation arose from the Pd(II)-catalyzed reactions of these compounds with aryl iodides with reaction periods of 4-24 h (except a few reactions which required 36 or 48 h). Notably, these reactions led to the construction of various unsymmetrical diarylmethane scaffolds, such as thiophene/furan-based arylheteroarylmethanes (3-6). Prolonging the reaction period to 48-70 h led to successive γ-C(sp)-H arylation/intramolecular amidation and the construction of both C-C and C-N bonds. Accordingly, these reactions led to the construction of new classes of pyrrolidone-ring annulated thiophene/furan-based heterocyclic scaffolds (e.g., 4,5-dihydro-6H-thieno[2,3-c]pyrrol-6-ones (8), 4,5-dihydro-6H-furo[2,3-c]pyrrol-6-ones (10), and 1-phenyl-1,2-dihydro-3H-benzo[4,5]thieno[2,3-c]pyrrol-3-ones (12)), and notably, compounds 8, 10, and 12 resemble the skeletons of 3-phenylisoindolin-1-ones.