Protecting-group-free catalytic asymmetric total synthesis of (-)-rosmarinecine

作者：Nemoto Hiroyuki; Tanimoto Kouichi; Kanao Yukiko; Omura Sohei; Kita Yasuyuki; Akai Shuji^*

来源：Tetrahedron, 2012, 68(36): 7295-7301.

DOI：10.1016/j.tet.2012.06.095

• Total synthesis
• Protecting-group free
• Rosmarinecine
• Dynamic kinetic resolution
• [3+2] Dipolar cyclization
• Lipase

The protecting-group-free asymmetric total synthesis of (-)-rosmarinecine was achieved in only four steps from the commercially available (+/-)-3-hydroxypyrrolidine hydrochloride (2a). The key steps include the direct oxidation of (+/-)-2a to (+/-)-3-hydroxy-1-pyrroline N-oxide (1a) using the Davis reagent and the domino reaction: viz., the lipase-catalyzed dynamic kinetic resolution of (+/-)-1a with 1-ethoxyvinyl ethyl maleate followed by the intramolecular [3+2] dipolar cycloaddition reaction of the generated optically active ester. Some insights into the mechanism of the racemization of the optically active la, observed during the enzymatic process, were also obtained.

• 出版日期2012-9-9