posted on 2018-10-17, 13:03authored byJoseph
R. Lizza, Maximilian Bremerich, Stephanie R. McCabe, Peter Wipf
The
2,2,6,6-tetramethylpiperidin-1-yloxycarbonyl (Tempoc) protecting
group is readily introduced by the reaction of amines with a new acyl
transfer reagent, 4-nitrophenyl (2,2,6,6-tetramethylpiperidin-1-yl)
carbonate (NPTC). Tempoc has a reactivity profile that complements
the commonly used t-butyloxycarbonyl (Boc) and benzyloxycarbonyl
(Cbz) protecting groups. Deprotection can be achieved under mild reductive
conditions with in situ generated Cu(I) species or
by thermolytic cleavage at 135 °C. Mechanistic studies on the
deprotection of Tempoc-indole suggest a combination of ionic and radical
fragmentation pathways under thermal conditions.