SEARCH Articles Figures Tables Acetals Lewis acid Acetic acid Lewis acids Acidity promotion Keten acetal Ketene acetal Ketenes Lewis acid Ketenes acetals Ketenes acids Ketenes silyl acetals Lewis acids 2 + 2-, promotion Lewis acids promoters Lewis promoter Lewis silyl ketene acetals Promoters acidic Promoters silylation Silyl acetate Silyl ketene acetals Silyl ketenes