Kawase M, Hirabayashi M, Kumakura H, Saito S, Yamamoto K
Faculty of Pharmaceutical Sciences, Josai University, Saitama, Japan.
Chem Pharm Bull (Tokyo). 2000 Jan;48(1):114-9. doi: 10.1248/cpb.48.114.
The Dakin-West reaction of N-alkoxycarbonyl-N-alkyl-alpha-amino acids (1a-j) with trifluoroacetic anhydride in the presence of pyridine gave alpha-amido trifluoromethyl ketones (2a-j), in which probable intermediates were mesoionic 1,3-oxazolium-5-olates (munchnones). The diastereoselective reduction of 2a-f with NaBH4 gave the threo-aminoalcohols (5a-f), which may be explained by the Felkin-Anh model. This was confirmed by converting 5a-f into trans-5-trifluoromethyl-2-oxazolidinones (6a-f) in good yields.
在吡啶存在下，N-烷氧羰基-N-烷基-α-氨基酸（1a - j）与三氟乙酸酐发生达金-韦斯特反应，生成α-氨基三氟甲基酮（2a - j），其中可能的中间体是内消旋离子型1,3-恶唑鎓-5-醇盐（门琴酮）。用硼氢化钠对2a - f进行非对映选择性还原，得到苏式氨基醇（5a - f），这可以用费尔金-安模型来解释。通过将5a - f高产率地转化为反式-5-三氟甲基-2-恶唑烷酮（6a - f），这一点得到了证实。
