Quinone Diels-Alder Reactions Catalyzed by a [(Schiff Base)Cr^III] Complex

Significance

The quinone Diels-Alder reaction is an important reaction providing precursors to many biologically important compounds. In this paper, the authors report an interesting finding that in catalyst preparation and isolation, the workup procedure is vital for obtaining the appropriately active catalyst for the quinone Diels-Alder reaction. Use of 3 N HCl (not neutral or 1 N HCl) provides the pseudo-octahedral chromium complex that gives high selectivity for the desired reaction. A variety of quinone derivatives and various dienes give consistently high yields, regioselectivity and enantioselectivity showing a very wide scope for this reaction.