Abstract
A metal-free procedure for the hydrogenative reduction of substituted N-heteroaromatics has been developed by using hydrosilanes as reducing agents. The optimized conditions were successfully applied to the reactions of quinolines, quinoxalines, and quinoline N -oxides. They were also effective for the reduction of quinolines bearing amino or hydroxy groups, where H 2 was evolved through dehydrogenative silylation of the amine or hydroxy moieties. Preliminary mechanistic studies revealed that the initial step in the catalytic cycle involves 1,4-addition of the hydrosilane to the quinoline to give a 1,4-dihydroquinoline; this is followed by (transfer) hydrogenation to deliver the tetrahydroquinoline as the final product.
Original language | English |
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Pages (from-to) | 2396-2400 |
Number of pages | 5 |
Journal | Synlett |
Volume | 28 |
Issue number | 18 |
DOIs | |
State | Published - 13 Nov 2017 |
Externally published | Yes |
Keywords
- Lewis acids
- boranes
- hydrogenation
- hydrosilanes
- quinolines
- quinoxalines