Topochemically related hormone structures. Synthesis of partial retro-inverso analogs of LH-RH

The syntheses of five partial retro-inverso luteinizing hormone-releasing hormone (LH-RH) analogs [g-Tyr5, m-Gly6]LH-RH, [g-Tyr5-r-Gly6, R,S-m-Leu7] LH-RH, [g-p-Glu1, m-His2]LH-RH, [g-p-Glu1-r-D-His-R,S-m-Trp3]LH-RH, and [g-Pro9-propionyl-des-Gly10]LH-RH, have been accomplished by solution methods. The choice of sequence to be reversed was based on suggested biodegradation mechanisms of LH-RH. A (gem)-diamino alkylidene residue, which was produced via Curtius rearrangement of a peptide segment, and a 2-substituted malonyl residue mark the initiating and terminating site, respectively, of the reversed sequence.