Synthesis and antifungal properties of benzylamines containing boronate esters

Abstract

Addition of 3-H2NC6H4Bpin (pin = 1,2-O2C2Me4) to a series of aldehydes and 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)acetophenone afforded the corresponding benzylideneamines in moderate to high yields. Hydroboration of these imines with catecholborane (HBcat, cat = 1,2-O2C6H4) at room temperature gives, upon aqueous workup, the corresponding borylamines. An X-ray diffraction study was carried out on imine 1h derived from 9-anthraldehyde and 3-H2NC6H4Bpin. Crystals of1h were triclinic, a = 9.6793(4) Å, b = 10.7397(4) Å, c = 11.5353(4) Å, α = 105.1890(10)o, β = 97.3030(10)o, γ = 102.1480(10)o, Z = 2 with space group P[Formula: see text] and crystals of N-[3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl]-4-methoxybenzylamine 2c were orthorhombic, a = 8.6612(4) Å, b = 10.3794(4) Å, c = 20.6033(9) Å, Z = 4 with space group P212121. Amines have been tested for their antifungal properties against Aspergillus niger and Aspergillus flavus.Key words: benzylamines, boronate esters, aminoboron, hydroboration, antifungal.