MW‐Enhanced High‐Speed Deprotection of Boc Group Usingp‐TsOH and Concommitant Formation ofN‐Me‐Amino Acid Benzyl Esterp‐TsOH Salts
摘要:
A high-speed, complete deprotection of Boc group from Boc amino acids and protected peptide esters employing p-TsOH in toluene under microwave irradiation is found to be complete in 30 s. The deprotection can be carried out in methanol and acetonitrile also. Under the present conditions, C-peptide benzyl esters and O-benzyl ethers have been found to be stable. This has permitted us to carry out the synthesis of [Leu] enkephalin employing the Boc/Bzl-group strategy. Further more, it has been found that both N-alpha-Fmoc and N-alpha-Z groups are completely stable. The present conditions can be extended for the concomitant removal of the Boc group and the formation of C-benzyl amino acid esters as well. This has been utilized for the synthesis of N-Me amino acid benzyl esters starting from Boc-N-Me amino acids in a single step.