A facile method for synthesis of polysubstituted naphthalene derivatives through pyrrolidine catalyzed domino reaction

Linear dialdehydes as promising substrates for aminocatalyzed transformations

“…Xu and co-workers described a quick method for the synthesis of polysubstituted naphthalenes 65 from easily accessible linear dialdehyde such as 2-(2-oxoethyl)benzaldehydes 61 and nitroalkenes11 in the presence of pyrrolidine 1 (Scheme 12). 36 This transformation proceeds through the cascade Michael/Henry reaction of in situ generated enamine 62 with 11 to give intermediate 63, which on further dehydration and oxidative aromatization as one pot four consecu-tive steps furnished the synthetically important naphthalene derivatives 65 in moderate yields (Scheme 12).…”

“…36 Xu and co-workers anticipated the application of dials for the enantioselective synthesis of nitrogen heterocycles such as substituted tetrahdro-pyridines 66 through amine catalysis in high 15 yields and excellent enantioselectivity's (up to 99% ee) (eqn. 1, Scheme 13).…”

Synthesis of polysubstituted arenes through organocatalytic benzannulation

“…In 2010, Xu and co-workers reported a [4 + 2] cascade reaction between dialdehydes 39 and nitroalkenes 40 via a Michael-Henry-dehydration-aromatization sequence. 27 Using pyrrolidine (Cat. 1) as the catalyst and DMAP as the additive in DCM and water (V DCM /V H 2 O ¼ 1/1) afforded benzene derivatives 41 in 45-65% yields, which bears three adjacent substituents.…”

Nitroalkenes in the synthesis of carbocyclic compounds

“…Xu et al described the synthesis of polysubstituted naphthalenes 291 by the reaction of 2-(2-oxoethyl) benzaldehyde 290, as an analogue of pentane-1,5-dial, and nitroalkenes 1 (Scheme 96). 164 Reaction was carried out using pyrrolidine as a catalyst and DMAP (0.2 equiv.) as an additive in methylene chloride in the presence of water to afford 3-nitro-2-aryl-1-naphthaldehyde 291 with moderate yield.…”