Ring Annelations via Reissert Compounds

Conversion of isoquinoline and related heterocycles to the correspondingReissert compound provides a starting point for the annelation of an additional ring.This has proved an attractive route to a wide range of ring systems.The review discusses the versatility of such procedures which include cycloaddition of cyclic Reissert salts with alkynes, addition of Reissert compound conjugate bases to suitable Michael acceptors, intramolecular cyclisations of Reissert compounds derived from chloroalkylsubstituted acid chlorides, the reaction of conjugate bases of chloroformate derived Reissert compound analogs with suitable electrophiles including heterocumulenes, and other methods.Annelations are exemplified with a variety of heterocycles in addition to isoquinoline and quinoline, including phthalazine, phenanthridine and 3,4-dihydro-0carboline.