gem-Diborylalkanes treated with LiTMP produce α-diborylalkane lithium bases that perform nucleophilic attack on vinyl aziridines with controlled regioselectivity. Preferred SN2 diborylalkylation ring opening reaction on the less sterically hindered position is observed with 1-tosyl-2-vinylaziridine, whereas exclusive SN2' nucleophilic attack occurs on 2-methyl-1-tosyl-2-vinylaziridine. Cyclic vinyl aziridines interact through a third venue, via SN2 diborylalkylation ring opening reaction on the allylic position. Homoallylic diboronates are formed with complete stereochemical control.