Tetrahedron letters

Practical synthesis of Boc and Fmoc protected 4-fluoro and 4-difluoroprolines from trans-4-hydroxyproline

L Demange, A Ménez, C Dugave

Index: Demange, Luc; Menez, Andre; Dugave, Christophe Tetrahedron Letters, 1998 , vol. 39, # 10 p. 1169 - 1172

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Citation Number: 68

Abstract

Boc-cis-4-fluoro-L-proline and 4-difluoro-L-proline, usable in classical peptide synthesis, were obtained in respectively 71%(3 steps) and 65%(4 steps) overall yields from the readily available trans-4-hydroxy-L-proline methyl ester. The corresponding fluorinated trans- isomer was isolated in 24% yield (5 steps). Transformation of Boc-protected compounds to their Fmoc-equivalents was performed in high yields.