Variously substituted 2‐vinylpyrroles underwent an endo‐addition [4+2] cycloaddition reaction with maleimides followed by a spontaneous highly diastereoselective (93–98% de) isomerization to give tetrahydroindoles in moderate to excellent yield. Treatment with activated MnO2 in refluxing toluene provided the corresponding indoles in moderate to good yield. This highly convergent methodology for formation of indoles is versatile and the starting materials are conveniently prepared. J. Heterocyclic Chem., (2009).

[reaction: see text] A Lewis acid-catalyzed formal cycloaddition of alpha,beta-unsaturated aldehydes with 6-methyl-4-hydroxy-2-pyrone, 1,3-diketones, and vinylogous silyl esters is described here.

Formic acid reacts with benzhydrol to give benzhydryl formate, which reacts with active methylene compounds in refluxing formic acid to give either C-alkylation or Ritter reaction products. The product formed is determined by the equilibrium enol content of the active methylene compound. These reaction conditions avoid the use of halogenated reaction solvents, and the pure products are isolated without recourse to chromatography.

The title compound crystallized as racemic tandem OO—H⋯O=C hydrogen-bonded dimers stacked along [100] in the space group P . This is the first crystallographically characterized example of a hydro­peroxide obtained from the autoxidation of a Diels–Alder adduct of a 2-vinyl five-membered heterocycle.

Benzhydrol reacts with nitriles in refluxing formic acid to produce amides arising from the Ritter reaction. This reaction does not require a strong acid catalyst, and the products are isolated without the need for chromatography. The conditions permit the preparation of acrylamides and methacrylamides without polymerization of the nitrile.