Enantio- and Diastereoselectivities in Chiral Sulfur Ylide Promoted Asymmetric Aziridination Reactions
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Title |
Enantio- and Diastereoselectivities in Chiral Sulfur Ylide Promoted Asymmetric Aziridination Reactions
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Creator |
JANARDANAN, D
SUNOJ, RB |
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Subject |
highly stereoselective-synthesis
polarizable continuum model corey-chaykovsky reaction ring-opening reactions aza-darzens reaction enantioselective synthesis dimethyloxosulfonium methylide mediated aziridination thermodynamic control efficient preparation |
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Description |
Density functional theory investigation on the factors controlling enantio- and diastereoselection in asymmetric aziridination reaction by the addition of chiral bicyclic sulfur ylides to substituted aldimines is presented. Hi-fi levels of enantioselection are predicted toward the formation of (2S,3S)-cis and (2R,3S)-trans aziridines by the addition of stabilized ylide (R = COMe) respectively to SO(2)Me and CO(2)Me protected aldimines. Similarly, high %ee is predicted for the formation of (2S,3R)-cis aziridines from semistabilized (R = Ph) ylide. Moderate to high levels of diastereoselectivity is noticed as well. The present study highlights that a correct prediction oil extent of enantioselection requires the knowledge of the activation barriers for elementary steps beyond the initial addition step. In the case of stabilized ylides the ring-closure (or elimination Of Sulfur compound) is found to be crucial in controlling enantio- and diastereoselection. A cumulative effect of electronic as well as other weak interactions is identified as factors contributing to the relative energies of transition states leading to enantio- and diastereomeric products for the stabilized ylide addition to aldimines. On the contrary, steric control appears quite dominant With semistabilized ylide addition. With the smallest substituent on ylide (R = Me), high enantioselectivity is predicted for the formation of (2R,3R)-trans aziridines although the %de in this case is found to be very low.
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Publisher |
AMER CHEMICAL SOC
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Date |
2011-07-14T01:13:35Z
2011-12-26T12:47:29Z 2011-12-27T05:35:01Z 2011-07-14T01:13:35Z 2011-12-26T12:47:29Z 2011-12-27T05:35:01Z 2008 |
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Type |
Article
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Identifier |
JOURNAL OF ORGANIC CHEMISTRY, 73(21), 8163-8174
0022-3263 http://dx.doi.org/10.1021/jo800652c http://dspace.library.iitb.ac.in/xmlui/handle/10054/3820 http://hdl.handle.net/10054/3820 |
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Language |
en
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