A convenient synthesis of 5'-triantennary N-acetyl-galactosamine clusters based on nitromethanetrispropionic acid.

Abstract A convenient method for the synthesis of several triantennary GalNAc clusters based on a nitromethanetrispropionic acid core was developed. The synthetic approach involves pentafluorophenolic ester intermediates which can be used in a one-pot, seven reaction procedure to quickly prepare a variety of triantennary GalNAc conjugated ASOs. The GalNAc clusters were conjugated to the 5′-end of an antisense oligonucleotide and evaluated for activity in primary mouse hepatocytes where they showed ∼10-fold improvement in activity.