Journal of the American Chemical Society
Communication
previously proposed for the nickel-catalyzed hydrocyanation
that provides Markovnikov addition products.1b
Scheme 2. Rh(I) Catalyst Synthesis and X-ray Structure
In conclusion, we have reported the first Rh-catalyzed anti-
Markovnikov hydrocyanation across both aromatic and
aliphatic terminal alkynes. The appropriate catalyst structure
was crucial for obtaining high selectivity, and has been
identified in the new catalyst TpRh(dppf).
ASSOCIATED CONTENT
* Supporting Information
The Supporting Information is available free of charge on the
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Experimental procedures, characterization data (PDF)
Data for C43H38BFeN6P2Rh (CIF)
AUTHOR INFORMATION
Corresponding Author
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Scheme 3. Proposed Mechanism
ORCID
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
We thank the Max-Planck-Institut fur Kohlenforschung for
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funding. We thank Jorg Rust for X-ray structure refinement and
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the MS department of the MPI KoFo for structure character-
ization.
REFERENCES
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(1) (a) Casalnuovo, A. L.; Rajanbabu, T. V. Transition-metal-
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both a bidentate and a tridentate, facial coordination
geometry.11 Moreover, oxidative addition of hydrogen cyanide
to Rh(I) has previously been demonstrated.12 Protonation to
yield the putative octahedral Rh(III) hydride I is possibly
followed by association of the acetylene (II) and vinylidene
formation (III).13 Rearrangement to Rh(III) alkenyl hydride IV
could then be followed by product forming reductive
elimination and formation of TpRh(dppf) to complete the
cycle. We do not have any structural information on the
structures relevant to the catalyst cycle beyond TpRh(dppf)
because the reaction with acetone cyanohydrin and TpRh-
(dppf) is rate-limiting, but the proposed cycle is consistent with
the data we have obtained. Vinylidene formation within the
catalyst cycle is consistent with observed inefficient hydro-
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