A new route to 1,1-difluoro-5-methylquasisilatrane (N→Si) F 2Si(OCH2CH2)2NMe is elaborated: the reaction of chlorinated methyltrifluorosilanes F3SiCH 3-nCln (n = 1-3) as well as trifluoro(3-chloropropyl) silane and trifluoro(propenyl)silane with N-methyl-bis(2-hydroxyethyl)amine. The reactivity of the silanes F3SiCH3-nCln increases with the number of chlorine atoms, that is, with the electronegativity of the CH3-nCln group. Pleiades Publishing, Ltd., 2011.