Use of Alloc-amino acids in solid-phase peptide synthesis. Tandem deprotection-coupling reactions using neutral conditions

The use of Alloc group in SPPS for the Nα protection of amino acids is an alternative to the Boc and Fmoc protecting groups. The smooth removal of Alloc group in neutral conditions with catalytic amounts of Pd(PPh3)4 in the presence of PhSiH3 as a scavenger for the allyl system permits orthogonality with the most common protecting groups. Furthermore, a tandem deprotection-coupling reaction allows the suppression of DKP formation in cases where this side reaction is troublesome.