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Extended Applications of Di‐ tert ‐butylsilylene‐Directed α‐Predominant Galactosylation Compatible with C2‐Participating Groups toward the Assembly of Various Glycosides
Author(s) -
Imamura Akihiro,
Kimura Akiyoshi,
Ando Hiromune,
Ishida Hideharu,
Kiso Makoto
Publication year - 2006
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200600832
Subject(s) - glycosylation , chemistry , threonine , serine , glycosyl , glycan , stereochemistry , alpha (finance) , biochemistry , glycoprotein , phosphorylation , medicine , construct validity , nursing , patient satisfaction
The high versatility of di‐ tert ‐butylsilylene(DTBS)‐directed α‐predominant galactosylation have been extended to the construction of difficult glycan sequences. First, to investigate the compatibility of the α‐predominant reaction with various glycosylation systems a variety of 4,6‐ O ‐DTBS‐tethered galactosaminyl or galactosyl donors were synthesized efficiently, which have C2‐participating groups with a wide variety of leaving groups such as alkylsulfenyl, halide, trichloroacetimidate groups. The results of the detailed examination of the glycosylation reaction using the glycosyl donors showed the wide scope of the 4,6‐DTBS‐directed α‐galactosylation. In the next step, the stereoselective construction of α‐GalN‐Ser/Thr sequences was examined by employing the DTBS‐directed glycosylation. As a result, various types of serine and threonine derivatives were glycosylated α‐selectively, producing α‐GalN‐Ser/Thr sequences in high yields. Moreover, the DTBS‐directed galactosylation was successfully applied for the synthesis of α‐tetrasaccharyl‐Ser segment of glycophorin A.