Complementary Asymmetric Routes to (R)-2-(7-Hydroxy-2,3-dihydro-1H-pyrrolo[1,2-a]indol-1-yl)acetate

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• 作者：Thomas O. Schrader ; Benjamin R. Johnson ; Luis Lopez ; Michelle Kasem ; Tawfik Gharbaoui ; Dipanjan Sengupta ; Daniel Buzard ; Christine Basmadjian ; Robert M. Jones
• 刊名：Organic Letters
• 出版年：2012
• 出版时间：December 21, 2012
• 年：2012
• 卷：14
• 期：24
• 页码：6306-6309
• 全文大小：235K
• 年卷期：v.14,no.24(December 21, 2012)
• ISSN：1523-7052

文摘

Two distinct and scalable enantioselective approaches to the tricyclic indole (R)-2-(7-hydroxy-2,3-dihydro-1H-pyrrolo[1,2-a]indol-1-yl)acetate, an important synthon for a preclinical S1P₁ receptor agonist, are reported. Route 1 employs a modified version of Smith鈥檚 modular 2-substituted indole synthesis as the key transformation. Route 2 involves a highly enantioselective CuH-catalyzed 1,4-hydrosilylation as the stereodefining step. Both routes can be performed without chromatography to provide multigram quantities of the tricycle in 鈮?8% ee.