1. Synthetic Organic Chemistry Laboratory, The Institute of Physical and Chemical Research (RIKEN), 2-1 Hirosawa, Wako, Saitama 351-01, Japan, Computer-Chemie-Centrum, Institute of Organic Chemistry, University of Erlangen-Nürnberg, Nägelsbachstrasse 25, D-91052 Erlangen, Germany, and Department of Knowledge-Based Information Engineering, Toyohashi University of Technology, 1-1 Tempaku, Toyohashi, Aichi 441, Japan