Application of stable fused dienolates for diversity oriented synthesis of 2,5-dioxo-5,6,7,8-tetrahydro-2H-chromene-3-carboxamides

One‐pot Synthesis of Benzo[4,5]imidazo[1,2‐a]pyridine Derivatives in Aqueous Conditions

“…2‐Cyanomethylbenzimidazole ( 9 ), dimedone ( 1a ), and 1,3‐cyclohexadione ( 1b ) are commercially available compounds. Other substituted 1,3‐cyclohexadiones 1c , 1d , 1e were obtained using the known method . The product 10a was previously described .…”

“…Our research during last years was devoted to elaboration of selectivity control methods for the synthesis of different heterocycles based on one‐pot reaction of α‐CH 2 ‐carbonyl compounds, dimethylformamide dimethylacetal (DMFDMA), and active methylene nitrile compounds . In particular, we have shown that this interaction using cyclic 1,6‐dicarbonyl compounds 1 and cyanoacetamides 3 have different outcome depending on reaction conditions (ways A–C , Scheme ). Moreover, the isolation of the polyfunctional intermediate enolates 4 allows their other transformations , for example, with aromatic amines (way D ).…”

“…Reaction conditions for way A : i ‐PrOH, piperidine (cat. ), microwave irradiation (MW) 100°C, 5 min ; way B : i ‐PrOH, piperidine (2.0 equiv), H 2 O, MW 120°C, 10 min ; way C : MeCN, piperidine (2.0 equiv), HCl (aqueous, 18%, 8.0 equiv), rt, 30 min ; way D : isolated enolate 4 , ArNH 2 (1.1 equiv), AcOH, rt . DMFDMA‐dimethylformamide dimethylacetal.…”

TWO-STAGE ONE-POT INTERACTION OF ACYCLIC Β-Ketoesters, DMFDMA AND 2-Cyanomethylbenzimidazole

“…Working in this field we studied previously several variations of a one-pot reaction between α-CH 2 -carbonyl compounds, dimethylformamide dimethylacetal (DMFDMA) and active methylene nitriles giving a great diversity of heterocyclic compounds of different classes [8][9][10][11][12][13]. Selectivity and pathways of such transformations depend on both the reaction conditions and the structure of initial compounds.…”

“…The use of piperidine as catalyst in i-PrOH under microwave irradiation at 100 ºC during 5 min [8] resulted in formation of pure expected product 8a, but the isolated yield was again very low (12%, Entry 9). Further experiments with catalytic amounts of piperidine, its stoichiometric quantities and excess at higher temperatures (Entries [10][11][12][13][14] showed that under such conditions increasing amounts of the undesired by-product 10a appeared in the isolated material. The reaction carried out at 160 °С during 20 min under microwave irradiation gave the pure by-product (10a, Entry 15).…”