Catalytic Enantioselective Friedel-Crafts Alkylations of Indoles with alpha’-Phosphoric Enones
Link: Org Lett ASAP
Hyeyeon Yang, Young-Taek Hong, and Sunggak Kim*
Center for Molecular Design & Synthesis and Department of Chemistry, School of Molecular Science, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea
Friedel-Crafts alkylation of indoles and pyrrole was accomplished. The catalyst for this reaction is the copper-py-box complex 1a and the alkyl counterparts were the alpha’-phosphate enones. Both indoles and pyrrole were alkylated at the 3-position on the ring.
The reaction was best conducted in CH2Cl2 at low temperatures. The reaction was applicable to a wide variety of both indoles and enones as shown in Tables 2 and 3. As can be seen, the reaction afforded the products in excellent yields and ees.
The reaction also worked well with N-methyl pyrrole.
The products could be elaborated in subsequent reactions as shown in equations below.
The mechanism of this reaction has been well-studied and it is represented in the figure below.
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