Elsevier

Tetrahedron Letters

Volume 41, Issue 6, 5 February 2000, Pages 839-842
Tetrahedron Letters

Novel 17α-ethynylestradiol derivatives: Sonogashira couplings using unprotected phenylhydrazines

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Abstract

The Pd/Cu catalyzed coupling of 17α-ethynylestradiol with halogenated amino-substrates was investigated. Iodophenylhydrazine and its protected derivatives reacted with 17α-ethynylestradiol to give 4-hydrazinophenyl derivatives without any degradation of the hydrazine group. Unprotected 3-, and 4-iodoaniline reacted similarly to produce the aminophenyl-derivatives. Protection of the amino group of halogenated benzylamines was required for alkyne coupling reactions, in order to avoid competing ortho-palladation of the benzylamine substrates.

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Acknowledgements

J.B.A. thanks the USAMRC Breast Cancer Research Program DAMD17-97-1-7120 and ACS-PRF for funding. We thank the reviewer for identifying Ref. 7.

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