2,3-Dihydro-lH-phenalene derivative 1 was synthesized by the intramolecular Diels-Alder reaction (21+22). 2,5_Dimethylpyrrole was used as a protecting group for the primary amine.
Interest in the lH-phenalene ring system1 originates from several directions. Early literature has been summarized by Reid2 who includes references to the naturally occurring lH-phenalene derivatives as plant and fungal pigments. Chemists have also been interested in this ring system as an organic ligand for the study of fluxionality and sigmatropic behavior associated with 6-and n-bonded metal derivatives of organic II ligands.29495 Another related interest is in the 1,9-disubstituted-phenalenyl system. It possesses a frontier molecular orbital which fulfills the requirements of a model which provides a mechanism for the injection of x-electron spin density from a Spiro substituent into a phosphazene linkage.8 Additional interest is in research aimed at the Favorski type zwitterion,y and most recently in the pseudopterosins, which are bioactive diterpene-pentose-glycosides. 'fa We became interested in this ring system as a template which, when properly substituted as for example in 1, bears a casual relationship to the morphine molecule.