科研之友
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摘要
Reaction of alpha-aminoacids, particularly proliries and their derivatives with carbonyl compounds via decarboxylative redo); process, is a viable strategy for synthesis Of structurally diverse nitrogen centered heterocyclics. In these processes, the decarboxylation is the essential driving force for the processes. The realiiation of the redox process, without decarboxylation May offer an opportunity to explore new reactions. Herein, we report the discovery of an unprecedented redox Claisen-type condensationaronatization cascade reaction of 4-substituted 4-hydrocypioline,and its esters with unreactive ketones. We found that the use of propionic acid as a catalyst and a co-solvent can change the reaction course. The commonly observed redox decarboxylation and aldol condensation reactions are significantly minimized. Moreover, Unreactive can effectively participate in the,Claisen condensation reaction. The new reactivity enables a redox cyclization via an unconventional, Claisen-type condensation reaction of in situ formed enamine intermediates from ketone precursors with 4-substittited 4-hydroxyproline and its esters as electrophilic acylation partners. Under the reaction conditions, the cascade process,proceeds highly regio- and stereoselectively to afford highly synthetically and biologically valued cis-2,3-dihydro-1H-pyrrolizin-1,ones with a broad substrate scope in efficient 'one-pot' operation, whereas such structures generally require Multiple steps.
- 出版日期2017-8-18
- 单位华东理工大学
