Isoquinoline-based polycyclic lactams such as isoindoloisoquinolinones, pyrroloisoquinolinones, and benzo[a]quinolizinones were successfully assembled from the corresponding imides by using a TfOH-mediated (TfOH = trifluoromethanesulfonic acid) imide carbonyl activation and cyclization strategy. By employing this simple method, the isoquinoline

An efficient and alternative synthetic approach has been developed to prepare various N-(arylethyl)piperazine-2,6-diones from 4-benzenesulfonyliminodiacetic acid and primary amines using carbonyldiimidazole in the presence of a catalytic amount of DMAP at ambient temperature. Piperazine-2,6-diones are successfully transformed to pharmaceutically useful pyridopyrazines or pyrazinoisoquinolines and ene-diamides via an imide carbonyl group activation strategy using a Brønsted acid. Subsequent dehydrosulfonylation reactions of the ene-diamides, in a one pot manner, smoothly transformed them to substituted pyrazinones. A concise synthesis of praziquantel (1) has also been achieved through this method.

A tandem Michael addition/carbocyclization of 3,4-dimethoxyphenethyl maleimide with carbon and sulfur nucleophiles is accomplished via a relay catalysis using γ-Al 2 O 3 /TfOH binary system. The X-ray Photoelectron Spectroscopy (XPS) analysis of binary system indicates the presence of AlF 3 , AlO(OH) species . This approach provides an easy access to 2-aryl or 2-thio aryl pyrrolo[2,1-a]isoquinolines in good yields in a tandem fashion. With suitable ratio of γ-Al 2 O 3 /TfOH binary system, the Michael addition of N/C/S nucleophiles to N-benzyl maleimide is also achieved. A key to the success of these reactions would be the generation of AlF 3 , AlO(OH) species from γ-Al 2 O 3 and TfOH, which might have delineated the disadvantageous background reactions usually displayed by a strong Brønsted acid such as TfOH.

A simple and practical method for synthesizing imidazol[1,5-a]indoles and pyrrolo[1,2-c]imidazoles has been developed. The present method uses microwave conditions and is free from the need for work-up and column chromatography.

Synthesis of Condensed Tetrahydroisoquinoline Class of Alkaloids by Employing TfOH-Mediated Imide Carbonyl Activation. -Racemic erythrinarbine (IVb) and further tricyclic lactams (II) and (IV) are readily prepared via a TfOH-mediated cyclization reaction. The reduction of lactam (IVc) with LiAlH 4 leads to racemic crispine A (V). The regioselectivity of the cyclization of unsymmetrical N-phenethylphthalimides depends on the structure of substrates. -(SELVAKUMAR, J.; RAO, R. S.; SRINIVASAPRIYAN, V.; MARUTHEESWARAN, S.; RAMANATHAN, C. R.; Eur. J. Org. Chem. 2015, 10, 2175-2188, http://dx.