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

A facile synthesis of sprio{1‐aza‐bicyclo‐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. AM1 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, ¹H NMR, and ¹³C NMR spectroscopies as well as mass spectrometry. Some of the synthesized cycloadducts showed moderate antioxidant activity. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 20:379–392, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20562