Preferred silyl-protecting groups are trimethylsilyl, triethylsilyl, t-butyldimethylsilyl,dibutylmethylsilyl, diphenylmethylsilyl, phenyldimethylsilyl, diphenyl-t-butylsilyl and analogous alkylated silyl radicals.A protected hydroxy group is a hydroxy group protected by any group commonly used for the temporary or permanent protection of hydroxy functions, e.g. the silyl, alkoxyalkyl, acyl or al