Synthesis of phosphotyrosine-containing peptides using bis-(2,2,2-trichloro)ethyl groups for phosphate protection

Suitability of bis-(2,2,2-trichloro)ethyl (Tc) groups for protection of phosphate moiety in Boc-mode synthesis of phosphotyrosine peptides is demonstrated Boc-Tyr(PO3Tc2)-OH and Fmoc-Tyr(PO3Tc2)-OH were prepared by acylating H-Tyr(PO3Tc2)-OH with (Boc)2O and Fmoc-ONSu, respectively. Phosphorus introduction was achieved by phosphorylating Boc-Tyr-OBzl with Tc phosphochloride. The Tc-phosphorus protector was found to be incompatible with the Fmoc group because the conditions of Fmoc removal (piperidine treatment) caused dephosphorylation. Complete NMR spectral assignments in the described compounds is presented. (Contribution No. 2398 from the Centre for Food and Animal Research).