|Budget Amount *help
¥3,400,000 (Direct Cost : ¥3,400,000)
Fiscal Year 1999 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1998 : ¥600,000 (Direct Cost : ¥600,000)
Fiscal Year 1997 : ¥2,300,000 (Direct Cost : ¥2,300,000)
New and useful reactions and compounds utilizing the characteristics of gem-dihalocyclopropanes and halocyclopropanes are developed from the many-sided, (1) cationic, (2) radical, and (3) anionic approaches.
(1) Regioselective and alternative, naphthalene- and naphthol-benzannulations of gem-dihalocyclopropane derivatives were performed by choosing either the order of the reaction sequences or the catalysts. These utilities could be demonstrated by the total synthesis of five natural lignan lactones and their analogs. A related 2, 5-diaryl-furan synthesis, a novel cyclopropane-shift type benzannulation, and a unique charity transfer into atropisomeric 1-arylnaphthalenes were also described. The variation in a variety of reactions is unequivocally due to the high degree of site-selectivity in the ring-openings in three bonds.
(2) Various Intramolecular, tandem-type, and sequential, stereoselective intermolecular radical additions using gem-dihalocyclopropane derivatives were performed, wherein consistent- stereoselective exo-face attack of olefins took place.
(3) Dimethylation and hydrodechlorination of gem-dichlorocyclopropanes with Grignard reagents promoted by Fe(III) or Co(II) catalyst were performed.
(4) Application of gem-dihalocyclopropanes to synthetic pyrethroid with three asymmetric centers on the cyclopropane ring was investigated.