P-24 フラン-イミニウムカチオンスピロ環化反応を用いた天然型マンザミンAの不斉全合成(ポスター発表の部)

概要

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We have already successeded the formal total synthesis of (±)-manzamine A (1) via key intermediate (3). For asymmetric total synthesis of (+)-manzamine A, we established effective asymmetric synthesis to key intermediate (+)-3 (Scheme 6). Catalytic allylation of 20 using only 0.15mol% [PdCl(allyl)]_2 and 0.36mol% ligand 23 gave 21 in 83% yield with 81% ee. Intramolecular Michael reaction of 28 which has β-TIPS ether proceeded with high diastereoselectivity. Therefore, optically pure (+)-3 was synthesized from ethyl 4-oxopiperidine-3-carboxylate in 12 steps and in 38% over all yield. Further investigation toward the asymmetric total synthesis of (+) manzamine A (1) from (+)-3 will be discussed.
天然有機化合物討論会の論文
2007-08-24