Synthesis of tritium labelled delta sleep‐inducing peptide

The α , β ‐dehydro precursor of the delta sleep‐inducing peptide (DSIP) for tritiation was prepared prior to tritiation using a 3+6 fragment coupling strategy on a solid support. The first fragment, α , β ‐dehydrotripeptide, was prepared in solution in five steps in 79% overall yield while the second fragment was obtained by a step by step peptide synthesis on a Wang resin using an Fmoc strategy. The α , β ‐dehydrotripeptide was coupled to the fragment linked to the resin, followed by a deprotection/cleavage step to yield the α , β ‐dehydro‐DSIP, 7 . Catalytic reduction of unsaturated DSIP using tritium gas and palladium oxide as catalyst gave [ 3 H]DSIP having a specific activity of 1.184 TBq/mmol(32 Ci/mmol). Copyright © 2001 John Wiley & Sons, Ltd.