1,4-addition of TMSCCl3to nitroalkenes: efficient reaction conditions and mechanistic understanding
Improved synthetic conditions allow preparation of TMSCCl3 in good yield (70 %) and excellent purity. Compounds of the type NBu4X [X=Ph3SiF2 (TBAT), F (tetrabutylammonium fluoride, TBAF), OAc, Cl and Br] act as catalytic promoters for 1,4-additions to a range of cyclic and acyclic nitroalkenes, in T...
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Wiley-VCH Verlag
2014
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| Online Access: | https://eprints.nottingham.ac.uk/46650/ |
| _version_ | 1848797377571323904 |
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| author | Wu, Na Wahl, Benoit Woodward, Simon Lewis, William |
| author_facet | Wu, Na Wahl, Benoit Woodward, Simon Lewis, William |
| author_sort | Wu, Na |
| building | Nottingham Research Data Repository |
| collection | Online Access |
| description | Improved synthetic conditions allow preparation of TMSCCl3 in good yield (70 %) and excellent purity. Compounds of the type NBu4X [X=Ph3SiF2 (TBAT), F (tetrabutylammonium fluoride, TBAF), OAc, Cl and Br] act as catalytic promoters for 1,4-additions to a range of cyclic and acyclic nitroalkenes, in THF at 0–25 °C, typically in moderate to excellent yields (37–95 %). TBAT is the most effective promoter and bromide the least effective. Multinuclear NMR studies (1H, 19F, 13C and 29Si) under anaerobic conditions indicate that addition of TMSCCl3 to TBAT (both 0.13 M) at −20 °C, in the absence of nitroalkene, leads immediately to mixtures of Me3SiF, Ph3SiF and NBu4CCl3. The latter is stable to at least 0 °C and does not add nitroalkene from −20 to 0 °C, even after extended periods. Nitroalkene, in the presence of TMSCCl3 (both 0.13 M at −20 °C), when treated with TBAT, leads to immediate formation of the 1,4-addition product, suggesting the reaction proceeds via a transient [Me3Si(alkene)CCl3] species, in which (alkene) indicates an Si⋅⋅⋅O coordinated nitroalkene. The anaerobic catalytic chain is propagated through the kinetic nitronate anion resulting from 1,4 CCl3− addition to the nitroalkene. This is demonstrated by the fact that isolated NBu4[CH2[DOUBLE BOND]NO2] is an efficient promoter. Use of H2C[DOUBLE BOND]CH(CH2)2CH[DOUBLE BOND]CHNO2 in air affords radical-derived bicyclic products arising from aerobic oxidation. |
| first_indexed | 2025-11-14T20:02:55Z |
| format | Article |
| id | nottingham-46650 |
| institution | University of Nottingham Malaysia Campus |
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| last_indexed | 2025-11-14T20:02:55Z |
| publishDate | 2014 |
| publisher | Wiley-VCH Verlag |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | nottingham-466502020-05-04T16:49:32Z https://eprints.nottingham.ac.uk/46650/ 1,4-addition of TMSCCl3to nitroalkenes: efficient reaction conditions and mechanistic understanding Wu, Na Wahl, Benoit Woodward, Simon Lewis, William Improved synthetic conditions allow preparation of TMSCCl3 in good yield (70 %) and excellent purity. Compounds of the type NBu4X [X=Ph3SiF2 (TBAT), F (tetrabutylammonium fluoride, TBAF), OAc, Cl and Br] act as catalytic promoters for 1,4-additions to a range of cyclic and acyclic nitroalkenes, in THF at 0–25 °C, typically in moderate to excellent yields (37–95 %). TBAT is the most effective promoter and bromide the least effective. Multinuclear NMR studies (1H, 19F, 13C and 29Si) under anaerobic conditions indicate that addition of TMSCCl3 to TBAT (both 0.13 M) at −20 °C, in the absence of nitroalkene, leads immediately to mixtures of Me3SiF, Ph3SiF and NBu4CCl3. The latter is stable to at least 0 °C and does not add nitroalkene from −20 to 0 °C, even after extended periods. Nitroalkene, in the presence of TMSCCl3 (both 0.13 M at −20 °C), when treated with TBAT, leads to immediate formation of the 1,4-addition product, suggesting the reaction proceeds via a transient [Me3Si(alkene)CCl3] species, in which (alkene) indicates an Si⋅⋅⋅O coordinated nitroalkene. The anaerobic catalytic chain is propagated through the kinetic nitronate anion resulting from 1,4 CCl3− addition to the nitroalkene. This is demonstrated by the fact that isolated NBu4[CH2[DOUBLE BOND]NO2] is an efficient promoter. Use of H2C[DOUBLE BOND]CH(CH2)2CH[DOUBLE BOND]CHNO2 in air affords radical-derived bicyclic products arising from aerobic oxidation. Wiley-VCH Verlag 2014-06-16 Article PeerReviewed Wu, Na, Wahl, Benoit, Woodward, Simon and Lewis, William (2014) 1,4-addition of TMSCCl3to nitroalkenes: efficient reaction conditions and mechanistic understanding. Chemistry - a European Journal, 20 (25). pp. 7718-7724. ISSN 1521-3765 brønsted base catalysis; catalysis; Michael addition; reaction mechanisms; trichloromethylation http://onlinelibrary.wiley.com/doi/10.1002/chem.201402394/abstract doi:10.1002/chem.201402394 doi:10.1002/chem.201402394 |
| spellingShingle | brønsted base catalysis; catalysis; Michael addition; reaction mechanisms; trichloromethylation Wu, Na Wahl, Benoit Woodward, Simon Lewis, William 1,4-addition of TMSCCl3to nitroalkenes: efficient reaction conditions and mechanistic understanding |
| title | 1,4-addition of TMSCCl3to nitroalkenes: efficient reaction conditions and mechanistic understanding |
| title_full | 1,4-addition of TMSCCl3to nitroalkenes: efficient reaction conditions and mechanistic understanding |
| title_fullStr | 1,4-addition of TMSCCl3to nitroalkenes: efficient reaction conditions and mechanistic understanding |
| title_full_unstemmed | 1,4-addition of TMSCCl3to nitroalkenes: efficient reaction conditions and mechanistic understanding |
| title_short | 1,4-addition of TMSCCl3to nitroalkenes: efficient reaction conditions and mechanistic understanding |
| title_sort | 1,4-addition of tmsccl3to nitroalkenes: efficient reaction conditions and mechanistic understanding |
| topic | brønsted base catalysis; catalysis; Michael addition; reaction mechanisms; trichloromethylation |
| url | https://eprints.nottingham.ac.uk/46650/ https://eprints.nottingham.ac.uk/46650/ https://eprints.nottingham.ac.uk/46650/ |