E. Lukevics,, V. Dirnens, P. Arsenyan
1996
Citations
0
Influential Citations
7
Citations
Journal
Main Group Metal Chemistry
Abstract
The addition of acetonitrile oxide to 1,3-divinyl-1,1,3,3-tetraphenyldisiloxane affords 1,3bis[5-(3-methylisoxazolino-2)]-1,1,3,3-tetraphenyldisiloxane, the latter exists as a mixture of R,Sand R,R-diastereoisomers. The bond angle of Si-O-Si fragment in R,S-isomer equals 180(0)° and in R,R-isomer it is 172.8(2)°. Introduction X-ray diffraction studies of organosiloxanes have shown that their Si-O-Si fragment is extremely flexible [1-3]. According to Gibbs' quantum-chemical calculations [4] not much energy is needed to increase the bond angle of Si-O-Si from its optimal value, 140°, up to 180°. Recently it has been found that the bond angle in Si-O-Si fragment changes from 147° to 163° within the temperature range -100°C to 28°C [5]. On the other hand, the number of phenyl groups in disiloxane molecules influences the magnitude of the Si-O-Si angle [1,3]. The Si-O-Si fragment in hexaphenyldisiloxane is linear [2], the substitution of the phenyl group for hydrogen [3,6] or for methyl [7,8] leads to the disiloxane group bending. Both steric and electronic factors may be the reasons for this variation [9]. We have studied the interaction of 1,3-divinyl-1,1,3,3-tetraphenyldisiloxane with acetonitrile oxide in the [2 + 3] cycloaddition reaction. This reaction results in the introduction of the heterocyclic isoxazoline group in the 1,3-positions of disiloxane. Results and Discussion 1,3-Divinyl-1,1,3,3-tetraphenyldisiloxane (1) reacts with acetonitrile oxide, generated by the dehydration of nitroethane with phenylisocyanate in the presence of the catalytic amount of triethylamine in benzene [10], affording 1,3-bis[5-(3-methylisoxazolino-2)]-1,1,3,3-tetraphenyldisiloxane (2): ^65 C6H5 C6H5 C6H5 ^ [ C H 3 C = N O] H 2 / C C H S i 0 S i CH-CH 2 H 2 C-CH-S i -0 -S i -CH-CH 2 c Q ^ 0 ^ c 6 H 5 c 6 h 5 h 3 c x n x c h 3