Preparation of Organosilicon Lewis acids

Simple organosilicon Lewis acids, for example trimethylsilyl triflate (la) [5], trimethylsilyl nonaflate (2) [6], iodotrimethylsilane [7], fert-butyldimethylsilyl triflate (Ic) [8], triisopropylsilyl triflate (Id) [8], etc., are commercially available, but because of their easy hydrolysis and the appearance of traces of a protic acid during storage. 

Protodesilylation of allyl- or aryl-substituted trialkylsilanes with an acid partner is a cleaner method, producing propene or an aromatic hydrocarbon as a volatile inert byproduct. Although some methods of isolation have been reported, they can usually be prepared in situ in aprotic media and employed without further purification. Methods of preparation of representative organosilicon Lewis acids, la, trimethylsilyl bis(trifluoro-methanesulfone)imide (7) [9], trimethylsilyl perchlorate (6a) [10], iodotrimethylsilane, and trimethylsilyl tetrakis(trifluoromethanesulfonyl)borate [11] are described below. In principle, these analogs are also accessible in a similar manner (Table 1) [2d]. 

Organosilicon Lewis acid Representative method of preparation Ref. Main purpose 

Et3SiC104 (6b) D 0 °C to room temp. (92 %) 10 Protection, Lewis acid 

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