20 タリウムの化学を利用した新反応群の開拓とその天然物合成への応用(口頭発表の部)  [in Japanese] 20 DEVELOPMENT OF NEW REACTIONS BASED ON THALLIUM CHEMISTRY AND ITS APPLICATION FOR THE TOTAL SYNTHESIS OF NATURAL PRODUCTS  [in Japanese]

In our continuing study on thallium compounds, such as (3-formylindo1-4-yl)thallium (8a) and (1-acety1-2,3-dihydroindo1-7-yl)thallium bis(trifluoroacetate) (8b), we have elaborated various new regioselective reactions which enable us to convert C-T1 bond in 8a and 8b either to C-C, C-Si, C-X, C-OH, C-N_3, C-NO_2, or C-SCN bond according to our own will. Utilizing above mentioned reactions, the first total synthesis of indole alkaloid, bipolaramide ((-)-5), was achieved in 47% overall yield starting from commercially available (2S)-(-)-2,3-dihydroindole-2-carboxylic acid ((-)-18) in three (or two) steps. Some derivatives, ((-)-22a-c), having dihalogeno or dialkenyl substituents at the 4 and 11 positions of (6aS)-cis-6a,7,13a,14-tetrahydropyrazino[1,2-a:4,5-a']diindole-6,13-dione were also readily prepared.