Use of dimethylformamide–sulphur trioxide complex as a sulphating agent of tyrosine

Abstract

Dimethylformamide–sulphur trioxide (DMF–SO₃) complex was found to be more suitable for tyrosine sulphation than pyridine–sulphur trioxide (Pyr–SO₃) complex, the most commonly used sulphur trioxide complex for sulphation. The work-up after sulphation using DMF–SO₃ was also easier than with Pyr–SO₃. The usefulness of DMF–SO₃ complex was demonstrated through the synthesis of two tyrosine sulphate [Tyr(SO₃H)]-containing peptides, leucine-enkephalin sulphate and leucosulfakinin-II.