| Abstract
| - 4-Amino-2-benzazepin-3-ones have proven very useful for studying the biologically active conformations of peptides. The synthesis of Pht-Aba-Xaa-OH by reaction of the corresponding 1,3-oxazolidin-5-one with trifluoromethanesulfonic acid (TFMSA) has been reported in the literature. However,when this procedure was applied to the preparation of Pht-Hba(Bn)-Gly-OH 8, many byproductswere formed and the yield of the desired aminobenzazepinones 7 and 8 was very low. We report inthis paper an efficient methodology for the synthesis of Pht-Hba(2,6-Cl2-Bn)-Gly-OH 17 startingfrom the commercially available tyrosine. In our procedure, the dipeptide Pht-Tyr(2,6-Cl2-Bn)-Gly-OH 15 is converted to the 1,3-oxazolidin-5-one 16 which then undergoes Friedel−Crafts cyclizationin the presence of tin tetrachloride to afford the desired 4-phthalimido-1,3,4,5-tetrahydro-8-(2,6-dichlorobenzyloxy)-2-benzazepin-3-one 17 in excellent yield.
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