Studies on positive inotropic agents. I. Synthesis of 3,4-dihydro-6-(4-(3,4-dimethoxybenzoyl)-1-piperazinyl)-2(1H)-quinolinone and related compounds.

Carboxylate Ligand-Exchanged Amination/C(sp3)–H Arylation Reaction via Pd/Norbornene Cooperative Catalysis

“…Importantly, o -iodoanilines ( 1r , 1s ) with large steric hindrance groups or aromatic groups do not affect the reaction. The substrate range of ortho -amination was also studied, and ketal-protected ( 3u ) and piperazinyl products ( 3v – 3x ), which are frequently important, biologically active skeleton, were obtained via this method. Other six-membered cyclic amines could be produced as well, but pyrrolidine was not successful (see Table ).…”

Palladium-Catalyzed Amination/Dearomatization Reaction of Indoles and Benzofurans

“…Amination reagents derived from cyclic amines, such as morpholine, thiomorpholine, pyrrolidine, hexamethyleneimine, piperidine, and piperazine, provided the required products ( 3a – o , 3r ) with good yields. Among them, morpholine ( 3a ), ketal-protected ( 3k ), and piperazinyl products ( 3l – o ) can be found in a large number of natural products or drug molecules. , Noncyclic amination reagents also afforded the target products in good yields ( 3p , 3q ). The structures of representative products 3a – c were confirmed by the single-crystal X-ray diffraction technique .…”

Synthesis of New 1-Aryl-4-(biarylmethylene)piperazine Ligands, Structurally Related to Adoprazine (SLV313)

“…Exposure of 18 to trifluoroacetic acid at r. t. smoothly afforded the required arylpiperazine salt 3 [14]. Attempts to convert compound 18 into the intermediate 4 proved to be unsuccessful; treating it with HCl at r. t. resulted in the formation of 3 only, whereas at higher temperature the reaction was sluggish and yielded fewer side products (Scheme 2).…”

“…The Buchwald-Hartwig coupling of 19 with 1-boc-piperazine in toluene at 110 • C yielded the arylpiperazine adduct 20 in 82 % yield. Hydrogenation of intermediate 20 in a pressure vessel in a Parr apparatus at 50 psi for 3 h afforded compound 21, which in turn was subjected to further hydrogenation at 65 psi for 20 h to obtain compound 22 in a high yield (96 %) [14]. Exposure of both compounds 21 and 22 to trifluoroacetic acid at r. t. produced the required intermediates 4 and 5, respectively (Scheme 3).…”