Ene reactions of Me2Si=C(SiMe3)2 (1) with propene or with methyl derivatives of propene and 1,3-butadiene, respectively, of the formula R 1 CH=CR2-CH2R3 take place regioselectively, as well as stereoselectively and are retarded by increasing bulk of R1, R3 (for example H < CH3 < CH=CH2 < CH=CHMe), as well as accelerated by an increasing tendency of R2 to donate electrons (for example H < CH3 ≈ CH=CH2 < CH2SiMe2[CH(SiMe3)2]). It is concluded from these studies, that ene reactions of 1 occur concerted and are HOMOene-LUMOenophile controlled.