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Synfacts 2021; 17(01): 0041
DOI: 10.1055/s-0040-1706628
Metals in Synthesis

Enantioselective Catalytic Hydroamination of Internal Alkenes

Contributor(s):
Paul Knochel
,
Dimitrije Djukanovic
Xi Y, Ma S, Hartwig JF. * University of California, Berkeley, USA
Catalytic Asymmetric Addition of an Amine N–H Bond Across Internal Alkenes.

Nature 2020;
DOI: 10.1038/s41586-020-2919-z.
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Key words

asymmetric synthesis - iridium catalysis - hydroamination

Significance

The authors report asymmetric hydroamination of internal alkenes. In this challenging transformation a cationic Ir-catalyst was used. Bulky SEGPHOS and SYNPHOS ligands were found to be optimal. Additional tuning of the catalyst counteranion and careful choice of the ammonia surrogate led to yields of up to 90% and enantiomeric excess of up to 98%.


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Comment

Deuterium labeling studies showed that addition across the double bond occurs in syn fashion. Based on kinetic experiments, migratory insertion is likely to be the rate-limiting step of the catalytic cycle. Furthermore, 2-amino-6-methylpyridine is a necessary component of the reaction. 2-Aminopyridine is not a competent ammonia surrogate and its addition inhibits the catalytic transformation.


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Publication History

Article published online:
16 December 2020

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