UMSETZUNG VON TRIMETHYLSILOXY-PHOSPHORYLVERBINDUNGEN MIT BORTRIFLUORID-ETHERAT; DARSTELLUNG UND NMR-SPEKTROSKOPISCHE UNTERSUCHUNG VON DONATOR-AKZEPTOR-KOMPLEXEN MIT DER PHOSPHORYL-GRUPPIERUNG ALS DONATOR

Abstract

The reaction of the a-trimethylsiloxy-phosphoryl compounds Ph₂C˭C(OSiMe₃)P(:O)R₂ [R = Me₂N, OMe, OPh] with F₃B · OEt₂ yielded the donor-acceptor-complexes 1-3 by cleavage of the Si‒O bond and elimination of Me₃SiF and Et₂O. The complexes 4 and 5 were formed analogously by the reaction of Me(Ph)C˭C(OSiMe₃)P(:O)R₂ [R = Me, Ph] with F₃B · OEt₂. The reaction of dimethyl- and diphenyl-2-trimethylsiloxy-3,5-di-tert-butylphenyl phosphinate with F₃B · OEt₂ produced the seven-membered ring-systems 6 and 7. Analogous products, 8-11, were formed by the reaction of (RO)₂P(:O)OR¹ [R = Me, ¹Pr; R¹ = 9-(10 trimethylsiloxy)phenanthryl, 2-trimethylsiloxy-3,4,5,6-tetrachlorophenyl] with F₃B · OEt₂. The reaction of Me₂P(:O)C(OSiMe₃)(H)CCl₃ with F₃B · OEt₂ produced the 1:1 complex 12 without cleavage of the Si‒O bond. From α-hydroxy phosphine oxides and F₃B · OEt₂ similarly, the 1:1 complexes, 13 and 14, were formed. Diphenyl-2-hydroxy-3,5-di-tert-butylphenyl phosphinate reacted with F₃B · OEt₂ to give the 1:1 complex 15. The structure of 15 was confirmed by X-ray structure analysis; the bond lengths at the bridging oxygen are P-O1 151.7, B-O1 152.8 pm. The donor-acceptorinteraction between the phosphoryl group and the boron atom was established by ¹⁹F-,³¹P- and, in the case of 6, 7, 11, and 15, by ¹¹B-n.m.r-spectroscopy.

Key Words:

• Boron trifluoride
• phosphoryl group
• X-ray structure
• donor-acceptor interaction.