Ascic E, Buchwald SL * Massachusetts Institute of Technology, Cambridge, USA
Highly Diastereo- and Enantioselective CuH-Catalyzed Synthesis of 2,3-Disubstituted Indolines.
J. Am. Chem. Soc. 2015;
137: 4666-4669
Key words
indolines - Markovnikov addition - organometallic reagents - copper
Significance
The L*CuH-catalyzed diastereo- and enantioselective synthesis of 2,3-disubstituted cis-indolines proceeds under mild conditions and tolerates bulky functional groups, including heterocycles, olefins, or substituted aromatic rings. A methyl substituent at the C-4 position of the indoline ring results in lower reactivity.
Comment
The yield of the reaction is significantly dependent on the choice of alcohol. t-BuOD is superior to t-BuOH, as it reduced the amount of byproduct by slowing the protonolysis of B. Interestingly, the reaction is highly cis-diastereoselective. Addition of triphenylphosphine as a secondary ligand significantly improves the catalyst turnover.
