Event Information
Xiaoqing Han
(Duke University)
Transition Metal-Catalyzed Addition of Carbon and Nitrogen Nucleophiles to Unactivated Olefins
Student Exams Seminar
Transition Metal-Catalyzed Addition of Carbon and Nitrogen Nucleophiles to Unactivated Olefins
- Abstract:
- Au[P(t-Bu)2o-biphenyl]Cl (1) catalyzed intramolecular hydroamination of alkenyl carbamates. Reaction of benzyl (2,2-diphenyl-4-pentenyl)-carbamate (2) with a catalytic 1:1 mixture of 1 and AgOTf (5 mol%) in dioxane at 60 °C for 18 hours led to the formation of benzyl 2-methyl-4,4-diphenylpyrrolidinylcarbamate (3) in 97% yield. The protocol was compatible with a range of labile carbamate groups, tolerated substitutions at the C(1), C(2), C(3), or C(4) position of the 4-pentenyl chain, and was applicable to the synthesis of piperidine derivatives. The Au(I)-catalyzed intramolecular hydroamination was also applied for allenyl carbamates.
Treatment of 2-(2,2-dicarbomethoxy-4-pentenyl)-1-methyl-1H-indole (4) with a catalytic mixture of AgOTf and [(S)-3,5-t-Bu-4-MeO-MeOBiphep]PtCl2 (5) (10 mol%) in methanol at 60 °C for 20 h let to the isolation of the corresponding tetrahydrocarbazole 6 in 93 % yield with 90 % ee. Electron-poor and electron-rich 2-alkenyl indoles also underwent efficient asymmetric cyclization reaction to form corresponding tetrahydrocarbazoles in excellent ee and yield. The platinum-catalyzed asymmetric intramolecular alkylation was effective for indoles with different substitutions and was also applied to form 7-membered ring in good yield and ee.
Ph.D. Defense Examination Seminar
Student Exams Seminar