The new photolabile protecting groups 4-allyl-5-methoxy-3-nitrobenzyl (AMNB) and 4-allyl-5-methoxy-3-nitrobenzyloxycarbonyl
(AMNBOC) with an allylic side chain can easily be obtained from vanillin. These protecting
groups can be introduced on the C- as well as on the N-terminus of peptides, and subsequent
ring-closing metatheses provides a straightforward protocol for the synthesis of cyclic
peptides. The protecting groups can be removed under UVA irradiation (365 nm).
Key words
amino acids - metathesis - peptides - photochemistry - photocleavage - protecting
groups