Stereoselective synthesis and antioxidant activity of azabicycloadducts derived from 9,10-phenanthrenequinone

A facile synthesis of sprio{1-azabicyclo-[3,3,0]-6-octene-8, 1'-phenanthrene}-2'-ones has been accomplished by [3 + 2] cycloaddition of azomethine ylide (amy) generated from 9,10-phenanthrenequinone and different secondary cyclic amino acids, namely, thiazolidine-4-carboxylic acid, L-pyrrolidine-2-carboxylic acid (L-proline), and piperidine-2-carboxylic acid (pipecolinic acid) with electron-deficient dipolarophiles in 67%-79% yield. AM] calculations have been performed to understand the stereochemical course of the cycloaddition. The products have been characterized by elemental analyses and spectroscopic techniques, namely IR, H-1 NMR, and C-13 NMR spectroscopies as well as mass spectrometry. Some of the synthesized cycloadducts showed moderate antioxidant activity. (C) 2010 Wiley Periodicals, Inc. Heteroatom Chem 20:379-392, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20562