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Nickel‐Catalyzed Hydrophosphonylation and Hydrogenation of Aromatic Nitriles Assisted by Lewis Acid
Author(s) -
Islas Rosa E.,
García Juventino J.
Publication year - 2019
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201801989
Subject(s) - chemistry , catalysis , selectivity , lewis acids and bases , yield (engineering) , medicinal chemistry , triethylborane , reagent , moiety , nickel , lewis acid catalysis , organic chemistry , chloride , materials science , metallurgy
In this paper, we describe the catalytic hydrophosphonylation of several aromatic nitriles used to synthesize α‐aminophosphonates (α‐APs) using commercially available trialkyl phosphites (P(OR) 3 , R=Et, i Pr, Bu,) and simple and inexpensive nickel chloride (NiCl 2 .6H 2 O) as the catalytic precursor. The use of triethylborane (Et 3 B) as a Lewis acid (LA) was mandatory in order to successfully perform H‐phosphite moiety incorporation at the CN bond of non‐activated benzonitriles (BN) derivatives. Interestingly, when a highly activated BN such as 2,3,4,5,6‐pentafluorobenzonitrile (BN‐g) was employed, it was possible to perform the reaction in the absence of an LA using milder reaction conditions. Also, we found that using HP(O)(O i Pr) 2 as a starting material afforded the aminobisphosphonate derivative with better selectivity than using the method involving P(OiPr) 3 as the initial reagent. Remarkably, when using HP(O)(OiPr) 2 with an excess of Et 3 B, the reaction's selectivity completely changed to yield N‐benzyl‐ benzylimine (BBI) and 2,4,5‐triphenylimidazole.