Efficient Synthesis of (S)-4-Phthalimido-1,3,4,5- tetrahydro-8-(2,6-dichlorobenzyloxy)-3-oxo-2H-2-benzazepin-2-acetic Acid (Pht-Hba(2,6-Cl2-Bn)-Gly-OH)1
- 13 September 2000
- journal article
- research article
- Published by American Chemical Society (ACS) in The Journal of Organic Chemistry
- Vol. 65 (20) , 6487-6492
- https://doi.org/10.1021/jo000530d
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 byproducts were formed and the yield of the desired aminobenzazepinones 7 and 8 was very low. We report in this paper an efficient methodology for the synthesis of Pht-Hba(2,6-Cl2-Bn)-Gly-OH 17 starting from 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 cyclization in 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.Keywords
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