Intramolecular Diels-Alder Additions. 1. Additions to Anthracene and Acridine

Article abstract of DOI:10.1021/jo01296a031

Intramolecular Diels-Alder reaction of suitably 9-substituted anthracenes at temperatures ranging from 25 to 220 deg C yields a wide variety of 9,12-bridged ethano- and ethenoanthracenes.Adducts having tree-, four-, and five-membered bridges, many incorporating heteroatoms such as oxygen, nitrogen, and sulfur, have been prepared.The ease of cyclization decreases with increasing bridge length.Neither the diene nor the dienophile need to carry activating groups; vinyl and ethynyl dienophiles add with equal ease.Cyclization of N-methyl-N-propargyl-9-acridinecarboxamide gives 31, the first thermal <4 + 2> adduct of an acridine.