Journal Article Brønsted Acid/Silane Catalytic System for Intramolecular Hydroalkoxylation and Hydroamination of Unactivated Alkynes

Shibuya, Masatoshi  ,  Fujita, Shoji  ,  Abe, Masanori  ,  Yamamoto, Yoshihiko

7 ( 4 )  , pp.2848 - 2852 , 2017-04-07 , ACS Publications
The Brønsted acid-catalyzed intramolecular hydroalkoxylation and hydroamination of unactivated alkynes are described. We found that unactivated alkynes are electrophilically activated by a catalytic amount of bis(trifluoromethanesulfonyl)imide to undergo intramolecular hydroalkoxylation and hydroamination. In the presence of silane, the formed reactive exo-cyclic enol ether and exo-cyclic enamine intermediates are effectively reduced to the corresponding saturated cyclic ethers and N-protected cyclic amines. The 2,4-cis and 2,5-cis pyrrolidine derivatives are produced with high diastereoselectivity. Taking advantage of this selectivity, the 2,5-cis-disubstituted prolinol was also synthesized from glutamic acid in the optically active form.

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