During our studies on the preparation of blo
cklike substituted 1,4-glu
cans by
cationi
c ring-opening polymerization,
1,2we found that TiCl4 behaves differently from common initiators like Et3O+X- (X = PF6, SbCl6), BF3·Et2O, ormethyl triflate, causing only ring opening under formation of
chars/alpha.gif" BORDER=0>-maltooligosyl chlorides bearing one free hydroxylgroup (4-OH) at the nonreducing end. These compounds are valuable building blocks for the preparation of newglyco-architectures since they are easily accessible starting materials for direct glycosylations or the preparationof a variety of oligomeric glycosyl donors like alkyl glycosides, thioglycosides, or azides. We successfully carriedout and optimized the TiCl4-promoted ring opening with per-O-methylated, per-O-ethylated, and temporarilyprotected per-O-allylated cyclodextrins of various ring size. 1H NMR spectroscopy and high-pressure liquidchromatography-evaporative light-scattering detection (HPLC-ELSD) were used to characterize the products.