Synthesis of homogalacturonan fragments

Article abstract of DOI:10.1080/07328300008544125

Glycosylation of the D-galacturonic acid ester derivatives 15 and 17, which are prepared directly from D-galacturonic acid, with the thioglycosides 28 and 32, derived from the same sugar, provides α(1→4)-linked dimers. The formation of the glycosidic linkage between the galacturonic acid moieties is best achieved by iodonium di-sym-collidine perchlorate promotion. Thus, the 4'-O-p-methoxybenzyl dimer 38 can be obtained in 64% yield. Partial deprotection of the 4'-O-position provided the glycosyl acceptor 36, which was coupled with the donor 32 to yield the a(1''→4')-linked trimer 39 (48%). Approximately 8% of the β(1''→4')-coupled isomer was observed in the ¹³C NMR spectrum of the reaction mixture.