1. Dipartimento di Chimica, Università degli Studi di Roma “La Sapienza”, P.le A. Moro 5, Roma, I-00185, Italy, Department of Organic Chemistry, Ivanovo State University of Chemical Technology, Friedrich Engels Pr-t 7, Ivanovo RF-153460, Russia, Department of Chemistry, Graduate School of Science, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan, and Department of Chemistry, University of Houston, Houston, Texas 77204-5003