Efficient preparation of TMSCCl2Br and its use in dichlorocyclopropanation of electron deficient alkenes

Lee, Darren S. and Durán-Peña, Maria Jesus and Burroughs, Laurence and Woodward, Simon (2016) Efficient preparation of TMSCCl2Br and its use in dichlorocyclopropanation of electron deficient alkenes. Chemistry - a European Journal, 2016 (22). ISSN 1521-3765

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Abstract

The reaction of excess TMSCl and LiCCl2Br at low temperature is a technically simple high yield route to TMSCCl2Br. The latter is a stable source of the dichlorobromomethide carbanion, which undergoes 1,4-addition with cyclic nitroalkenes and (E)-fumarates leading to dichlorocyclopropanes after bromide explusion. For nitrostyrenes the reaction arrests at the 1,4-addition product. Low temperature NMR studies and DFT calculations suggest the formation of an ‘ate’ species [(nitronate)SiFMe3]- which, upon boil off of TMSF at 10 - 20 °C, yields the cyclopropane. DFT calculations also support the experimental differences between fluoride and acetate as promotors.

Item Type: Article
Additional Information: This is the peer reviewed version of the following article: Lee, D. S., Durán-Peña, M. J., Burroughs, L. and Woodward, S. (2016), Efficient Preparation of TMSCCl2Br and Its Use in Dichlorocyclopropanation of Electron-Deficient Alkenes. Chem. Eur. J.2016, 22., which has been published in final form at doi:10.1002/chem.201600607. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.
Keywords: Dichlorocyclopropane, Michael Addition, Cyclopropanation, Conjugate Addition, Cyclopropane
Schools/Departments: University of Nottingham UK Campus > Faculty of Science > School of Chemistry
Identification Number: https://doi.org/10.1002/chem.201600607
Depositing User: Bramwell, Roseanna
Date Deposited: 27 Apr 2016 09:40
Last Modified: 22 Sep 2016 12:06
URI: http://eprints.nottingham.ac.uk/id/eprint/32995

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