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Zhang, M.; Hanson, P. R., Science of Synthesis, (2007) 20, 873.
The lithium salts of tritylhydrazones 43 of both aldehydes and ketones react with methyl crotonate at low temperature to form C-trapped azo compounds, which decompose homolytically, with loss of nitrogen, below room temperature to afford saturated esters 44 in poor yields (Scheme 12).[49] The major reaction pathway in these processes appears to be a basic deprotonation of methyl crotonate by azo anions to give recovered tritylhydrazone. In the presence of excess triethylsilane or phenylsilane, α,β-unsaturated esters 45 react with excess alkylmercury(II) chloride in dimethyl sulfoxide to give reductively alkylated products, esters 46, in good to excellent yields in most cases (Scheme 12).[50,51] An unusual cobalt(II)-catalyzed intermolecular reductive coupling is that of α,β-unsaturated esters 48 with alkynes 47 to give esters 49 (Scheme 12).[52] This reaction is highly chemo-, regio-, and stereoselective, providing an effective route for C—C bond formation under mild conditions.
Meeeee 88 Meeeeeeee M—M Meee Meeeeeeee ee α,β-Meeeeeeeeee Meeeee[88–88]
Meeeeeeeeeee Meeeeeeee
Meeee 8-Meeeee-8-eeeeeeeeee-8-eeeeee (88, M8 = Me; M8 = Me; M8 = Me); Meeeeee Meeeeeeee:[88]
M eeeeee 88-eM eeee eeeeeeeeee [MeM8(MMe8)8] (88 ee, 8.88 eeee), Me8M (88 ee, 8.88 eeee), eee Me eeeeee (888 ee, 8.88 eeee) eee eeeeeeeee eee eeeeee eeee M8 ee eeeee eeeeee. Meeeeee eeeeeeeee eeeee MeMM (8.8 eM), 8-eeeeeeeeee-8-eee (88, M8 = Me; M8 = Me; 888 ee, 8.88 eeee), eeeee eeeeeeee (88, M8 = Me; 888 ee, 8.88 eeee), eee M8M (88.8 µM, 8.88 eeee) eeee eeeee ee eee eeeeee eeee ee eeeeeee. Mee eeeeeee eee eeeeeee eee eeeeee ee 88°M eee 88 e, eee eee eeee eeeeee, eeeeeee eeee MM8Me8, eee eeeeeee eeeee eee eee 88 eee. Mee eeeeeee eee eeeeeeee eeeeeee Meeeee eee e eeeeee eee eee eee eeeeee eeee MM8Me8. Mee eeeeeeee eee eeeeeeeeeeee eee eee eeeeeee eee eeeeeeee ee eeeeee eeeeeeeeeeeeee (eeeeee eee, eeeeee/MeMMe); eeeee: 888 ee (88%).
References
| [49] | Meeeeee, M. M.; Meeeeeeee, M. M.; Meeeeee, M. M.; Meeee, M. M.; Meeeeeeee, M. M.; Meeee, M. M. M., Meeeeeeeeee, (8888) 88, 8888. |
| [50] | Meeeeee, M. M.; Mee, M.-M., Meeeeee, (8888), 888. |
| [51] | Meeeeee, M. M.; Mee, M.-M., Meeeeeeeeee Meee., (8888) 88, 8888. |
| [52] | Meee, M.-M.; Mee, M.-M.; Meeee, M.-M., M. Me. Meee. Mee., (8888) 888, 8888. |
Meeeeee Meeeeeeeeee
- 8.Meeeee-Meee, (8888) 88/8e, 888.
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