A new synthetic approach is described for building the coumarin scaffold through the Lewis acid‐promoted cyclization of novel aryl 3‐(dimethylamino)prop‐2‐enoates 2a–2f. The latter precursors were prepared via aminomethylenation of the corresponding aryl acetates 4a–4f with the Bredereck reagent. This approach was used for the synthesis of biologically active natural compounds 1a–1f, through a three‐step procedure starting from the corresponding phenols.

A highly efficient and regioselective synthesis of 1,2-dihydroquinolines via a multicomponent reaction between an aniline and two ketones is described. This reaction was catalyzed by magnesium bromide and carried out under solvent-free conditions. When the reaction was performed by using 3-substituted anilines and nonsymmetrically substituted ketones, principally a single product was found among the four expected regioisomers. A variety of anilines and ketones, including cyclic ketones, were evaluated providing a series of 1,2-dihydroquinolines with diverse substitution patterns. A study of the mechanism is discussed. There is evidence of the in situ formation of the imine as a result of the reaction between the aniline and one of the ketones, before annulation to the heterocyclic ring.

An efficient synthetic approach to the substituted benzo[b]furan and benzo[b]thiophene scaffolds by iodine‐mediated cyclization of the corresponding enaminones is described. This protocol was applied to a large series of these latter precursors to afford the respective benzoheterocycles substituted at the C‐2 position by a carbonyl group functionality. A study of the factors that control this process reveals that the reactivity depends on the presence of electron‐donor groups in the aryl ring of the aryloxycarbonylic and arylthiocarbonylic moieties.

Synthesis of Nuevamine Aza-Analogues by a Sequence: I-MCR-Aza-Diels--Alder-Pictet-Spengler. -A one-pot procedure including Ugi three-component reaction, aza-Diels-Alder cycloaddition and aromatization provides key intermediates (V). They are converted to alkaloid scaffolds of type (VI) by S-oxidation, acyloxysulfonium β-elimination and Pictet-Spengler cyclization. -(ISLAS-JACOME, A.; CARDENAS-GALINDO, L. E.; JEREZANO, A. V.; TAMARIZ, J.; GONZALEZ-ZAMORA, E.; GAMEZ-MONTANO*, R.; Synlett 2012, 20, 2951-2956, http://dx.doi.org/10.1055/s-0032-1317622 ; Dep. Quim., Univ. Guanajuato, 36050 Guanajuato, Mex.; Eng.) -Mais 17-152

The synthesis of 2-carbonylindoles was achieved via a iodine-mediated cyclization of the corresponding enaminone precursors, which were formed by reaction of the -arylaminomethylene carbonyl derivatives with N,N′-dimethylformamide dimethyl acetal (DMFDMA). An alternative and more efficient procedure consisted of a similar cyclization of the enaminones, but under solvent-free and grinding reaction conditions. In another iodine-promoted procedure, 2-carbonyl-3-dimethylaminoindoles were synthesized via a one-pot cascade reaction between the -arylaminomethylene carbonyl derivative and DMFDMA.

A series of nuevamine aza-analogues were prepared in moderate to good yields in two reaction steps. The synthetic strategy involves an isonitrile-based multicomponent reaction, including an aza-Diels-Alder cycloaddition and Pictet-Spengler reaction as postcondensation.

An efficient synthetic approach for the construction of the 1-oxygenated carbazole core is described. The condensation of cyclohexane-1,2-diones with a series of anilines yielded the corresponding 2-anilinocyclohex-2-en-1-ones, followed by the one-pot aromatization/methylation process of the latter to provide N-aryl-2-methoxyanilines. A palladium(II)-catalyzed cyclization of these Naryl-2-methoxyanilines afforded the desired 1-methoxycarbazole frame in high overall yields. This protocol was implemented for the total synthesis of the naturally occurring glycozolicine and 6-methoxymurrayanine.

Application to the Preparation of Natural Alkaloids. -Starting with the regioselective condensation of anilines with cyclohexane-1,2-diones, a convenient synthesis of 2-methoxy substituted diarylamines (V) is demonstrated. Subsequent microwave promoted Pd-catalyzed cyclization offers the title compounds (VI) in good yields. -(BAUTISTA, R.; JEREZANO, A. V.; TAMARIZ*, J.; Synthesis 2012, 21, 3327-3336, http://dx.