Stereoselectivity in addition of N-nitrenes to olefins
- 1 January 1977
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 1
- No. 20,p. 2242-2249
- https://doi.org/10.1039/p19770002242
Abstract
Additions of phthalimidonitrene and 2,3-dihydro-2-oxobenzoxazol-3-ylnitrene to αβ-unsaturated esters, styrenes, and dienes have been examined by n.m.r. at temperatures (< – 20 °C) low enough for kinetically-formed invertomer ratios at nitrogen in the aziridine products to be observed. In many cases, addition is (a) stereospecific; only that invertomer having the olefin substituent (CO2Me, Ph, or CR:CH2)cis to the heterocycle (phthalimide, benzoxazolone) being observable and (b) contrathermodynamic, as can be shown by n.m.r. at temperatures >10 °C when thermodynamic equilibration by inversion at the aziridine ring nitrogen is complete. Some evidence is presented which suggests that the nitrenes add to the s-cis- conformations of the dienes, and a possible explanation for the high Stereoselectivity is offered.Keywords
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