86822-56-2Relevant academic research and scientific papers
Electroactivated alkylation of amines with alcohols: Via both direct and indirect borrowing hydrogen mechanisms
Appiagyei, Benjamin,Bhatia, Souful,Keeney, Gabriela L.,Dolmetsch, Troy,Jackson, James E.
supporting information, p. 860 - 869 (2020/02/21)
A green, efficient N-alkylation of amines with simple alcohols has been achieved in aqueous solution via an electrochemical version of the so-called "borrowing hydrogen methodology". Catalyzed by Ru on activated carbon cloth (Ru/ACC), the reaction works well with methanol, and with primary and secondary alcohols. Alkylation can be accomplished by either of two different electrocatalytic processes: (1) in an undivided cell, alcohol (present in excess) is oxidized at the Ru/ACC anode; the aldehyde or ketone product condenses with the amine; and the resulting imine is reduced at an ACC cathode, combining with protons released by the oxidation. This process consumes stoichiometric quantities of current. (2) In a membrane-divided cell, the current-activated Ru/ACC cathode effects direct C-H activation of the alcohol; the resulting carbonyl species, either free or still surface-adsorbed, condenses with amine to form imine and is reduced as in (1). These alcohol activation processes can alkylate primary and secondary aliphatic amines, as well as ammonia itself at 25-70 °C and ambient pressure.
Stereoselective Reductions of Substituted Cyclohexyl and Cyclopentyl Carbon-Nitrogen ? Systems with Hydride Reagents
Hutchins, Robert O.,Su, Wei-Yang,Sivakumar, Ramachandran,Cistone, Frank,Stercho, Yuriy P.
, p. 3412 - 3422 (2007/10/02)
Reductions of 3- and 4-substituted cyclohexyl imines, iminium salts, and enamines (via iminium ions) with various hydride reagents reveal that while small reagents (NaBH4, NaBH3CN) favor axial approach as observed with the corresponding ketones, even moderately bulky reagents (i.e., acetoxyboranes) attack preferentially from the equatorial side.This is in direct contrast to the results observed for the same reagents with the corresponding ketones and is interpreted as implying that additional steric interactions induced by the nitrogen substituents encumber axial attack by substituted hydride reagents and force approach from the equatorial direction.The very bulky tri-sec-butylborohydride anion affords highly stereodiscriminating equatorial attack.Reductions of 2-alkylcyclohexyl and 2-alkylcyclopentyl imines and enamines also proceed with high stereoselectivity to give cis-2-alkyl cyclic amines with both hindered and unhindered reagents.This is interpreted to be the result of (1) augmented steric interactions between nitrogen substituents and equatorial 2-alkyl groups (1,3-allylic strain) which induces conformational changes to favor the axial 2-alkyl conformer and (2) hindrance toward equatorial approach by reagents induced by axial alkyl substituents.The result is that equatorial approach is favored with equatorial 2-alkyl conformers and preferential axial approach with axial 2-alkyl conformers, leading to stereoselective production of cis-2-alkylamines. trans-2-n-Propyl-4-tert-butylcyclohexanone is reduced by LiBH(sec-Bu)3 preferentially from the axial direction in contrast to the usual highly selective equatorial attack observed with other cyclohexanones.
