Visible-Light-Driven Decarboxylative Borylation: Rapid Access to α- and β-Amino-boronamides
Andrea Serafino, Hugo Pierre, Franck Le Vaillant, Julien Boutet, Gérard Guillamot, Luc Neuville, Géraldine Masson*
*Institut de Chimie des Substances Naturelles (ICSN), CNRS
UPR 2301, Université Paris-Saclay, 1 avenue de la Terrasse, 91198 Gif-sur-Yvette,
France, Email: geraldine.masson
cnrs.fr
A. Serafino, H. Pierre, F. Le Vaillant, J. Boutet, G. Guillamot, L. Neuville., G. Masson, Org. Lett., 2023, 25, 9249-9254.
DOI: 10.1021/acs.orglett.3c04067
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Abstract
An efficient visible-light-induced decarboxylative borylation of α- and β-amino redox-active esters with bis(catecholato)diboron, followed by transamination with 1,8-diaminonapthalene (DANH2) provide a series of boronamides in good yields in a one-pot procedure. The photochemical can also be conducted under flow conditions.
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General procedure for the Borylation
A dried 10 mL Schlenk tube equipped with a magnetic stirring bar was charged with substrate N-hydroxy phthalimide activated ester (1.0 equiv.) and bis(catecholato)diboron (1.5 equiv.). The tube was evacuated and backfilled with N2 before the addition of dry and degassed DMAc (0.1 M). The reaction mixture was degassed via three freeze-pump thaw cycles and irradiated at 456 nm with a Kessil lamp (25% of power) at the distance of 8 cm during 22 h. After this time, 1,8-diaminonaphthalene (3.0 equiv.) was added under nitrogen atmosphere and the solution was stirred at 90 °C for 3 h. The mixture was then cooled to r.t. and diluted with MTBE (15 mL). The organic layer was washed with 0.4 M HCl twice, with 0.2 M NaOH twice, and with brine. The organic layer was then dried over MgSO4 and concentrated under reduced pressure affording the crude reaction mixture which was purified by chromatography on silica gel (Heptane/EtOAc, gradient: 95:5 to 60:40)
*Sometimes B2dan2, obtained as coproduct, could precipitate after the addition of MTBE. If happen, it can be easily removed by filtration.
reaction setup
Key Words
α-aminoboronates, alkylboronates, photochemistry
ID: J54-Y2023
