New synthetic routes for styrene derivatives having both trimethylsilyl and hydroxyalkyl groups were investigated. Reactions between oxirane (Sa) and chemical s p i e s present in an equilibrium system resulting from 4-(trimethylsilylmethyl)styrene (1 s) and lithium diisopropylamide (2) in tetrahydrofuran give an addition product 8 a ) between 2 and Sa preferentially. By using alkylsubstituted oxiranes such as ethyloxirane (5e) and tert-butyloxirane (Se), a i : 1 addition reaction of 1s with the oxiranes takes place predominantly to form i-alkyl-3-trimethylsilyl-3-pVinylphenyl-I-propanol(8) homologues. From results of studies on the reaction between 2 and several oxiranes, it was concluded that the selective formation of 8 homologues was attained by suppression of reactions between oxirane and 2 owing to steric hindrance between alkyl substituents of oximne and isopropyl groups of 2. The reactivity of 8 in polymerization reaction was also estimated on the basis of spectroscopic measurements. 8 was found to have a reactivity similar to that of 4-(trimethylsilylmethyl)styrene (1 9). a) Present address: 4 3 l b , 3b: R = H: Is, 3s: R = Si(CH,),
Experimental partAll procedures such as distillations, metalations, silylations and ring-opening reactions were carried out under purified nitrogen to eliminate oxygen and moisture.Materials-Commercial tetrahydrofuran 0. diisopropylamine @PA), 4-methylstyrene (MST), trimethylsilyl chloride (TMSC) and oxiranes were purified by conventional methods7). Commercial oxirane (5 a) was stirred over a mixture of potassium hydroxide and calcium hydride at -20 "C, then it was collected in atrap cooled with a liquid nitrogen bath. Purified 5 a was stored under nitrogen at -20°C. Commercial methyloxirane (Sb), ethyloxirane (Sc), 1.1-dimethyloxirane (5d) and tert-butyloxirane (5e) were purified by distillation over a mixture of potassium hydroxide and calcium hydride. 4-(Tkimethylsilyhnethyl)styrene (1 s) was prepared according to our previous paper'). Methods for purification of other materials were described in our previous paper ').
Reaction between lithium diisopropylamide (LDA; 2) and oxiranes (5):One of the