A new type of fluoride ion catalyzed allylation agent, o-bis(allyldimethylsilyl)-benzene (la) and bis(allyldimethylsilyl)methane (Ib), can be successfully utilized for various carbonyl substrates. The rate acceleration is ascribable to the shift of equilibrium to complex with Bu4NF by the favorable chelation of bis(silane) toward the fluoride ion. (C) 1998 Elsevier Science Ltd. All rights reserved.