Mechanochemical Grinding Diels-Alder Reaction: Highly Efficient and Rapid Access to Bi-, Tri-, and Tetracyclic Systems
Grinding of various electron-deficient dienophiles with diverse dienes in a pestle and mortar for 1-15 minutes afforded the corresponding Diels-Alder adducts in quantitative yields under catalyst-free and solvent-free conditions, without the necessity for