Magata Takuji, Hirokawa Yoshimi, Furokawa Aya, Takeuchi Kazuhisa, Ohtomo Yoshiaki, Kino Toshitaka, Kominami Jun, Nakai Yuto, Kitamura Maria, Maezaki Naoyoshi
Faculty of Pharmacy, Osaka Ohtani University.
Chem Pharm Bull (Tokyo). 2018;66(4):416-422. doi: 10.1248/cpb.c17-00907.
Positional isomers of naturally occurring peptide subunits were synthesized via highly diastereoselective reduction of tert-butylsulfinyl ketimines as a key reaction. While NaBH reduction of ketimines derived from 2-thiazolyl ketones afforded the (R,R)-isomer with moderate diastereoselectivity, L-Selectride reduction afforded the (R,S)-isomer as the sole product. In contrast, ketimines derived from tert-butyl 2-thiazolyl ketone afforded the (R,R)-isomer with low diastereoselectivity by both NaBH and L-Selectride reduction. Stereochemistry of the reaction was discussed based on calculation of the conformational energies for ketimines.
通过叔丁基亚磺酰基酮亚胺的高度非对映选择性还原这一关键反应，合成了天然存在的肽亚基的位置异构体。虽然用硼氢化钠还原源自2-噻唑基酮的酮亚胺以中等非对映选择性得到了（R，R）-异构体，但用L-Selectride还原得到了（R，S）-异构体作为唯一产物。相比之下，源自叔丁基2-噻唑基酮的酮亚胺经硼氢化钠和L-Selectride还原均以低非对映选择性得到了（R，R）-异构体。基于酮亚胺构象能的计算对反应的立体化学进行了讨论。
