2,2-Dimethyl-4-(4-methoxy-phenoxy) butanoate and 2,2-dimethyl-4-azido butanoate: two new pivaloate-ester-like protecting groups.

The title compounds were developed to extend the available orthogonalities within the class of protecting groups removed by assisted cleavage. The mild, complementary (oxidative vs reductive) reaction conditions for the removal, together with their pivaloate-like character, were exploited, in combination with a levulinoyl-ester functioning as a third orthogonal protecting group, in the assembly of a Streptococcus mutans hexasaccharide built up from a oligorhamnose backbone featuring beta-glucosyl appendages.