Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.

Science 30 October 2009:
Vol. 326. no. 5953, pp. 706 - 708
DOI: 10.1126/science.1178165
Prev | Table of Contents | Next

Reports

Synergic Sedation of Sensitive Anions: Alkali-Mediated Zincation of Cyclic Ethers and Ethene

Alan R. Kennedy,1 Jan Klett,1 Robert E. Mulvey,1,* Dominic S. Wright2

Deprotonation of alkyl and vinyl carbon-hydrogen bonds for synthetic purposes is often hindered not merely by the need for an exceptionally strong base, but by the inherent instability of the resultant anion. Metalation of cyclic ethers adjacent to oxygen, for example, has invariably initiated a ring-opening decomposition pathway. Here, we show that the use of a bimetallic base can overcome such instability through a cooperative combination of zinc-carbon and sodium-oxygen bonding. Both tetrahydrofuran and tetrahydropyran reacted cleanly over days at room temperature to yield {alpha}-zinc–substituted products that were sufficiently stable to be isolated and crystallographically characterized. A related zincation-anion trapping strategy, with sodium replaced by potassium, induced clean deprotonation of ethene to yield a stable product. Preliminary electrophilic quenching experiments with the {alpha}-zinc–substituted cyclic ethers and benzoyl chloride gave satisfactory yields of the tetrahydrofuran-derived ketone but only trace amounts of the tetrahydropyran-derived ketone.

1 WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow G1 1XL, UK.
2 Chemistry Department, Cambridge University, Lensfield Road, Cambridge CB2 1EW, UK.

* To whom correspondence should be addressed. E-mail: r.e.mulvey{at}strath.ac.uk

Read the Full Text


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
The Basics of Zinc Activation.
I. Marek (2009)
Science 326, 673-674
   Abstract »    Full Text »    PDF »


To Advertise     Find Products

Science. ISSN 0036-8075 (print), 1095-9203 (online)