Regioselective Borylation of the C-H Bonds in Alkylamines and Alkyl Ethers. Observation and Origin of High Reactivity of Primary C-H Bonds Beta to Nitrogen and Oxygen was written by Li, Qian;Liskey, Carl W.;Hartwig, John F.. And the article was included in Journal of the American Chemical Society in 2014.Formula: C12H14N2O This article mentions the following:
Borylation of aliphatic C-H bonds in alkylamines and alkyl ethers to form primary aminoalkyl and alkoxyalkyl boronate esters and studies on the origin of the regioselectivity of these reactions are reported. The products of these reactions can be used directly in Suzuki-Miyaura cross-coupling reactions or isolated as air-stable potassium trifluoroborate salts. Selective borylation of the terminal C-H bond at the positions β to oxygen and nitrogen occurs in preference to borylation of the other terminal C-H bonds. Exptl. studies and computational results show that C-H bond cleavage is the rate-determining step of the current borylation reactions. The observed higher reactivity of C-H bonds at the terminal position of ethylamines and ethers results from a combination of attractive Lewis acid-base and hydrogen-bonding interactions, as well as typical repulsive steric interactions, in the transition state. In this transition state, the heteroatom lies directly above the boron atom of one boryl ligand, creating a stabilizing interaction between the weak Lewis acid and Lewis base, and a series of C-H bonds of the substrate lie near the oxygen atoms of the boryl ligands, participating in a set of weak C-H···O interactions that lead to significant stabilization of the transition state forming the major product. In the experiment, the researchers used many compounds, for example, 4-(Morpholinomethyl)benzonitrile (cas: 37812-51-4Formula: C12H14N2O).
4-(Morpholinomethyl)benzonitrile (cas: 37812-51-4) belongs to nitriles. The electronic structure of nitriles is very similar to that of an alkyne with the main difference being the presence of a set of lone pair electrons on the nitrogen. In addition, Nitriles can react with alkynes, which leads to an increase in carbon chain length (carbocyanation).Formula: C12H14N2O
Referemce:
Nitrile – Wikipedia,
Nitriles – Chemistry LibreTexts