Efficient Synthetic Approach to Substituted Benzo[b]furans and Benzo[b]thiophenes by Iodine‐Promoted Cyclization of Enaminones

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 (±)-desethylrhazinal using a tandem radical addition-cyclization process

The indolizidine ring system present in (±)-rhazinal, was assembled using a xanthate-based sequential intermolecular radical addition-cyclization process. The novel (±)-desethylrhazinal was prepared in seven steps in approximately 12% overall yield from 2-formylpyrrole, using this strategy.     

Preparation of Propanedioic Acid, (Anilinometwlene) Alkyl Esters by Direct Condensation

The title compounds, 7a-e, were obtained by direct acid catalyzed condensation of diethyl malonate and triethyl ortho formate, with the corresponding aniline in acetic anhydride. In the absence of acetic anhydride amido esters 8a-e were formed.