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The Synthesis of [4‐Carboranylalanine, 5‐Leucine]‐Enkephalin (Including an Improved Preparation of t ‐Butoxycarbonyl‐ L ‐ o ‐carboranylalnine, New Derivatives of L ‐Propargylglycine, and a Note on Melanotropic and Opiate Receptor Binding Characteristics)
Author(s) -
Fauchère JeanLuc,
Leukart Othmar,
Eberle Alex,
Schwyzer Robert
Publication year - 1979
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19790620502
Subject(s) - chemistry , stereochemistry , tripeptide , enkephalin , leu enkephalin , phenylalanine , (+) naloxone , receptor , amino acid , antagonist , biochemistry , opioid
The title compound, an analogue of [Leu 5 ]‐enkephalin with L ‐ o ‐carboranylalanine replacing L ‐phenylalanine in position 4, was prepared by fragment condensation. The analogue has a 3‐fold higher affinity for rat brain opiate receptors in the [ 3 H]naloxone competition assay than natural [Leu 5 ]‐enkephalin. Like [Leu 5 ]‐enkephalin and N a ‐acetyl‐[Leu 5 ]‐enkephalin, the N ‐terminal tripeptide fragment, H · Tyr‐Gly‐Gly · OH, had no melanotropic activity in the Rana pipiens frog skin assay. A convenient, direct synthesis of methyl t ‐butoxycarbonyl‐ L ‐propargylglycinate is described, and the 13 C‐NMR. spectra of L ‐ o ‐carboranylalanine recorded. The procedure was extended to the preparation of BOC · Car‐Leu · OMe from BOC · Pra‐Leu · OMe. A number of new propargylglycine derivatives are reported.