Friedlander synthesis of chiral alkyl-substituted 1,10-phenanthrolines

The synthetic scope of the Friedlander condensation in the preparation of c hiral alkyl-substituted 1,10-phenanthrolines has been investigated. A range of chiral [x,y-b]-cycloalkeno-condensed phenanthrolines has been prepared in one step from steroidal or other cyclic ketones from the chiral pool and 8-amino-7-quinolinecarbaldehyde (1) via base-catalyzed condensation. Phena nthroline derivatives are formed in good yields with unhindered ketones, bu t the reaction proceeds even with sterically congested substrates such as c amphor, albeit in low yield. The utility of the Friedlander condensation ha s been extended to the synthesis of chiral 3-alkyl-substituted phenanthroli nes from monoalkyl-substituted acetaldehydes.