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Studies Directed to the Synthesis of Oligochitosans – Preparation of Building Blocks and Their Evaluation in Glycosylation Studies
Author(s) -
Grann Hansen Signe,
Skrydstrup Troels
Publication year - 2007
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200700048
Subject(s) - chemistry , trifluoromethanesulfonate , pyridine , glycosylation , glycosyl , dichloromethane , combinatorial chemistry , protecting group , organic chemistry , chloride , medicinal chemistry , catalysis , solvent , biochemistry , alkyl
Thioglucosaminides with four different N ‐protecting groups, Troc, Phth, Alloc and PNZ could selectively be benzoylated at the C3 and C6‐hydroxy groups in good yields without the requirement for low‐temperature techniques. These reactions could be performed by refluxing a solution of the N ‐protected amino sugars with benzoyl chloride, 4‐(dimethylamino)pyridine and pyridine in dichloromethane. The efficacy of these thioglycosides both as donors and acceptors for the construction of chitosans was evaluated. Whereas, the thioglycosides could be easily coupled to simple alcohols in excellent yields using the glycosylation promoting system N ‐iodosuccinimide and TMS triflate, these conditions could not effectuate coupling to the C4‐hydroxy group possessing flanking benzoyl protecting groups. On the other hand, exploitation of Crich's O ‐glycosylation conditions involving a glycosyl triflate intermediate provided two different 1,4‐linked disaccharides in good yields.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)