Prepn: M. Schmeisser et al., Ber. 103, 868 (1970); H. W. Roesky, H. H. Giere, Z. Naturforsch. 25B, 773 (1970); D. Haebich, F. Effenberger, Synthesis 1978, 755; T. Morita et al., ibid. 1981, 745. As catalytic reagent: H. Vorbrueggen, K. Krolikiewicz, Angew. Chem. Int. Ed. 14, 421 (1975); as silylating agent: G. A. Olah et al., J. Org. Chem. 46, 5212 (1981).