A programmed synthesis of neoglycopeptides has been developed in which two,
similar or different, glycoside moieties could be attached either (i) at t
he N-terminal of short peptides or (ii) one at the N-internal and the other
(s) at the N-terminal site, in a highly flexible and controlled manner. A s
tepwise branching of N-terminal peptides has been achieved by glycoside ald
ehyde reductive amination followed by the glycoside carboxylic acid couplin
g (model 1). In another approach, after N-alkylation with glycoside aldehyd
e, the N-glycosylated derivative is subjected to peptide synthesis. This is
then followed by the attachment of the second glycoside moiety at the N-te
rminal using either glycoside aldehyde or glycoside carboxylic acid derivat
ive (model 2). Alternatively, the attachment of second and third glycoside
derivatives could be achieved simultaneously, by reductive amination/carbox
ylic acid couplings (model 3). The methodologies presented here are highly
versatile and combine diversity in both peptides/pseudopeptides and glycosi
de moieties.