Harnying Wacharee, Neudörfl Jörg-M, Berkessel Albrecht
Department of Chemistry (Organic Chemistry) , University of Cologne , Greinstrasse 4 , 50939 Cologne , Germany.
Org Lett. 2020 Jan 17;22(2):386-390. doi: 10.1021/acs.orglett.9b04034. Epub 2020 Jan 6.
An efficient oxidative NHC-catalyzed one-step transformation of ()- or ()-8-oxocitronellal to nepetalactone (NL) in enantio- and diastereomerically pure form has been developed. Several new and "easy to make" N-Mes- or N-Dipp-substituted 1,2,4-triazolium salts carrying nitroaromatic groups on N1 were synthesized and evaluated as precatalysts in combination with base and stoichiometric organic oxidant. Under optimized conditions, NLs are accessible in very good yields and diastereomerically pure under mild conditions. The oxidant used could be recovered and recycled under operationally simple conditions.
已开发出一种高效的氧化NHC催化的一步法，可将（+）-或（-）-8-氧代香茅醛转化为对映体和非对映体纯形式的荆芥内酯（NL）。合成了几种新的且“易于制备”的N-甲基磺酰基（N-Mes）或N-二异丙基苯基（N-Dipp）取代的1,2,4-三唑鎓盐，其N1上带有硝基芳基，并与碱和化学计量的有机氧化剂组合作为预催化剂进行评估。在优化条件下，可在温和条件下以非常高的产率获得非对映体纯的NL。所用的氧化剂可以在操作简单的条件下回收和循环利用。
