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.

The synthetic application of 4,5-bis-alkylidene-1,3-oxazolidin-2-ones led to the efficient and regioselective synthesis of 2-(3H)-benzoxazolones and diarylamines with a short methodology. They were also valuable synthons in a total synthesis of naturally occurring carbazoles. New enantiopure 4-oxazoline-2-one and 4-methylene-2-oxazolidinone were prepared via a one-pot microwave (MW)-promoted condensation of α-ketols and an enantiopure isocyanate. These enamides were efficient nucleophiles when added to Michael acceptors to give a series of compounds with quaternary stereocenters in fairly good stereoisomeric ratios. The novel approach for the synthesis of benzofurans and indoles by intramolecular cyclization of enaminones has been applied in the preparation of furobenzofurans starting from benzo-bis-enaminones.

No abstract

No abstract