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Lithium 2,2,6,6-tetramethylpiperidide-mediated α- and β-lithiations of epoxides: Solvent-dependent mechanisms
| Content Provider | Semantic Scholar |
|---|---|
| Author | Wiedemann, Sean H. Ramírez, And Antonio Collum, David B. |
| Copyright Year | 2003 |
| Abstract | Lithium 2,2,6,6-tetramethylpiperidide (LiTMP)-mediated α- and β-lithiations of epoxides are described. LiTMP displays a markedly higher reactivity than does lithium diisopropylamide, consistent with literature reports. Detailed rate studies of LiTMP/THF and LiTMP/Me2NEt mixtures reveal similar rates but significant mechanistic differences. LiTMP-mediated α-lithiation of cis-cyclooctene oxide with subsequent oxacarbenoid formation and transannular C−H insertion proceeds via monosolvated dimers in both THF and Me2NEt. LiTMP-mediated β-lithiation of 2,3-dimethyl-2-butene oxide affords the corresponding allylic alcohol via a monosolvated monomer in THF and a monosolvated dimer in Me2NEt. We discuss how the solvent-dependent aggregation of LiTMP markedly influences the rate profile. The reaction transition structures are examined with density functional computations. |
| Starting Page | 15893 |
| Ending Page | 15901 |
| Page Count | 9 |
| File Format | PDF HTM / HTML |
| DOI | 10.1021/ja0304087 |
| Volume Number | 125 |
| Alternate Webpage(s) | http://collum.chem.cornell.edu/publications/82.pdf |
| Alternate Webpage(s) | https://doi.org/10.1021/ja0304087 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
