Synthesis of (R)-and (S)-(glu) thz and the corresponding bisthiazole dipeptide of dolastatin 3

RC Kelly, I Gebhard, N Wicnienski

Index: Kelly, Robert C.; Gebhard, I.; Wicnienski, N. Journal of Organic Chemistry, 1986 ,  vol. 51,  # 24  p. 4590 - 4594

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Citation Number: 45

Abstract

Dolastatin 3 (1) has been reported to be a cyclic pentapeptide containing two thiazole amino acids,(g1y) Thz (2) and (g1n) Thz (3). The syntheses of (R)-and (S)-(g1u) Thz (8a, b) and (g1u) Thz-(g1y) Thz (lla, b) derivatives suitable for elaboration to dolastatin 3 are described. A key feature of the (g1u) Thz syntheses is the selective thiation of a primary amide with Lawesson's reagent in the presence of ester and urethane functionalities.