Dynamic NMR study of the oxaphosphetane complexation with lithium during the Wittig reaction |
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| Authors: | Aurelia Pascariu Mircea Mracec Stefan Berger |
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| Affiliation: | 1. Romanian Academy, Institute of Chemistry Timisoara, Bd. Mihai Viteazul 24, RO‐300223 Timisoara, Romania;2. Institute of Analytical Chemistry, University Leipzig, Johannisallee 29, D‐04103 Leipzig, Germany |
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| Abstract: | Dynamic NMR spectroscopy at very low temperatures (148–182 K) reveal the dynamic behavior of the (2‐tri(3‐furyl)‐3‐methyl‐4‐cyclopropenyl‐oxaphosphetane) generated during a Wittig reaction between tri(3‐furyl)ethylphosphonium iodine and cyclopropylaldehyde. The possibility of formation of different adducts between Li+ ions and oxaphosphetane or betainic intermediates was checked calculating the formation enthalpies using the MNDO, AM1, and PM3 semiempirical MO methods. The observed species are interpreted as oxaphosphetane complexes with lithium ions present in solution. Quantum mechanical calculations confirm the spectroscopic results. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008 |
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| Keywords: | Wittig reactions quantum mechanical calculations dynamic NMR spectroscopy oxaphosphetanes lithium complexation |
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