摘要:
                                One-pot 2-O-alkylation of L-ascorbic acid involving an in situ 3-O-silylation and desilylation sequence was investigated. Initially the 3-OH group was masked with a t-butyldimethylsilyl (TBDMS) group followed by alkylation of the 2-OH group. Removal of the TBDMS group using 20% sulfuric acid also resulted in hydrolysis of the 5,6-O-isopropylidene to give 2-O-alkyl derivatives of L-ascorbic acid. Selective removal of the 3-O-TBDMS with tetrabutylammonium fluoride (TBAF) gave 5,6-O-isopropylidene-2-O-alkyl derivatives of L-ascorbic acid in good overall yields. Through the application of this protocol, 5,6-O-isopropylidene 2-O-alkyl derivatives of L-ascorbic acid as well as 2-O-alkyl derivatives of L-ascorbic acid may be easily accessed.