Synthesis of 2-anilinobenzimidates, anthranilamides, and 2,3-dihydroquinazolin-4(1H)-ones from N-heterocyclic carbenes of indazole

Organic Synthesis with N‐Heterocyclic Carbenes of Indazole: Synthesis of Benzo(thio)imidates, Benzo[d][1,3]thiazines and Quinazoline‐4‐thiones

“…The same is true for the hydrolysis of phosphorylated thiobenzamides, [50] preparations starting from aldehydes, benzotriazole, and unsubstituted thiobenzamide, [51] and substitution reactions of primary amines with benzocarbodithioesters. [52] In support of our continued studies of N-heterocyclic carbenes in heterocycle synthesis [36][37][38][39][40]53] we report here on benzothioimidate as well as anthranilthioamide preparations that employ N-heterocyclic carbenes of indazole and the conversion of the latter into the title ring systems.…”

“…Melting points are uncorrected and were determined with an apparatus according to Dr. Tottoli (Büchi), yields are not optimized. The syntheses of starting materials 1a-c, [39] 1d, [36] 1e, [53] 1f [40] and 4a-f [40] have been described in our earlier publications.…”

“…A solution of corresponding benzamide 4a-f [40] (0.5 mmol) and Lawesson's reagent (0.6 mmol in 20 mL of toluene) was stirred 3 h at 60°C. After evaporation of the solvent in vacuo the crude reaction product was purified by flash column chromatography (petroleum ether/ethyl acetate = 3:1) and dried in vacuo.…”

“…These readily rearrange to acridines [39] or undergo trapping reactions with oxygen nucleophiles. [40] We therefore started a project to explore their synthetic potential with sulfur nucleophiles and aimed at the synthesis of the first representatives of 2-anilinobenzothioimidates IV and 2-anilinobenzothioamides V as shown in Scheme 3. able benzamides as precursors [40] which were subsequently thionated, [41,42] to biologically active compounds. [43] Thionations can be performed by P 4 S 10 /silicon oil, [44] aqueous ammonium sulfide, [45] or polymer-supported thionation reagents.…”

From betaines to anionic N-heterocyclic carbenes. Borane, gold, rhodium, and nickel complexes starting from an imidazoliumphenolate and its carbene tautomer

“…Since the first isolation of a stable N-heterocyclic carbene (NHC) [1] in 1991 this compound class has provided numerous highly efficient ligands of NHC-metal catalysts for cross-coupling reactions [2–7], versatile organocatalysts [8–10], and starting materials for heterocycle syntheses [11–13]. Consequently books [14–16] and reviews cover the range from NHC structures in the light of their early history [17], syntheses [6,18], coordination chemistry [19–20], and catalysis [21–22], to biological activities of NHC complexes [23–24].…”