Practical Procedures for the Preparation of N-tert-Butyldimethylsilylhydrazones and Their Use in Modified Wolff−Kishner Reductions and in the Synthesis of Vinyl Halides and gem-Dihalides

Michael E. Furrow and Andrew G. Myers*
Contribution from the Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138
J. Am. Chem. Soc., 2004, 126 (17), pp 5436–5445
DOI: 10.1021/ja049694s
Publication Date (Web): April 8, 2004
Copyright © 2004 American Chemical Society
*

In papers with more than one author, the asterisk indicates the name of the author to whom inquiries about the paper should be addressed.

, myers@chemistry.harvard.edu

Abstract

Abstract Image

In this work we develop practical chemistry for the preparation of N-tert-butyldimethylsilylhydrazone (TBSH) derivatives from carbonyl-containing compounds and show that these products serve as superior alternatives to simple hydrazones in Wolff−Kishner-type reduction reactions, in the Barton vinyl iodide preparation, in the synthesis of vinyl bromides, and in the synthesis of gem-diiodides, gem-dibromides, and gem-dichlorides. In our new procedure for silyl hydrazone synthesis, aliphatic and aromatic ketones and aldehydes are shown to undergo highly efficient coupling (typically >95% yield) to form the corresponding TBSH derivatives when combined with equimolar amounts of 1,2-bis(tert-butyldimethylsilyl)hydrazine (BTBSH) and a catalytic quantity of scandium trifluoromethanesulfonate (typically, 0.01 mol %), neat, or in solvent. Optimized procedures are provided for the use of TBSH derivatives in a Wolff−Kishner-type reduction protocol that proceeds at low temperature (23−100 °C) and in a single reaction flask. Similarly, protocols for the use of TBSH derivatives as precursors to vinyl halides and gem-dihalides are described in detail.

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History

  • Published In Issue May 05, 2004
  • Received January 16, 2004

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