TY - JOUR
T1 - Formation of Enamines via Catalytic Dehydrogenation by Pincer-Iridium Complexes
AU - Lu, Yansong J.
AU - Zhang, Xiawei
AU - Malakar, Santanu
AU - Krogh-Jespersen, Karsten
AU - Hasanayn, Faraj
AU - Goldman, Alan S.
N1 - Funding Information:
We thank Zhuo Gao, Drs. Amlan Ray, Sabuj Kundu, and Ritu Ahuja for generously providing samples of various catalysts. We gratefully acknowledge support by the National Science Foundation through grant CHE-1465203. The authors acknowledge the Office of Advanced Research Computing at Rutgers, The State University of New Jersey for providing access to the Amarel cluster and associated research computing resources.
PY - 2020/3/6
Y1 - 2020/3/6
N2 - Di-isopropylphosphino-substituted pincer-ligated iridium catalysts are found to be significantly more effective for the dehydrogenation of simple tertiary amines to give enamines than the previously reported di-t-butylphosphino-substituted species. It is also found that the di-isopropylphosphino-substituted complexes catalyze dehydrogenation of several β-functionalized tertiary amines to give the corresponding 1,2-difunctionalized olefins. The di-t-butylphosphino-substituted species are ineffective for such substrates; presumably, the marked difference is attributable to the lesser crowding of the di-isopropylphosphino-substituted catalysts. Experimentally determined kinetic isotope effects in conjunction with DFT-based analysis support a dehydrogenation mechanism involving initial pre-equilibrium oxidative addition of the amine α-C-H bond followed by rate-determining elimination of the β-C-H bond.
AB - Di-isopropylphosphino-substituted pincer-ligated iridium catalysts are found to be significantly more effective for the dehydrogenation of simple tertiary amines to give enamines than the previously reported di-t-butylphosphino-substituted species. It is also found that the di-isopropylphosphino-substituted complexes catalyze dehydrogenation of several β-functionalized tertiary amines to give the corresponding 1,2-difunctionalized olefins. The di-t-butylphosphino-substituted species are ineffective for such substrates; presumably, the marked difference is attributable to the lesser crowding of the di-isopropylphosphino-substituted catalysts. Experimentally determined kinetic isotope effects in conjunction with DFT-based analysis support a dehydrogenation mechanism involving initial pre-equilibrium oxidative addition of the amine α-C-H bond followed by rate-determining elimination of the β-C-H bond.
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U2 - 10.1021/acs.joc.9b02846
DO - 10.1021/acs.joc.9b02846
M3 - Article
C2 - 31990556
AN - SCOPUS:85081902787
VL - 85
SP - 3020
EP - 3028
JO - Journal of Organic Chemistry
JF - Journal of Organic Chemistry
SN - 0022-3263
IS - 5
ER -