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Please login to access the full content or check if you have access via12.1.2.2.1.4 Variation 4: From 3-Acyldihydrofuran-2(3H)-ones
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Stanovnik, B.; Svete, J., Science of Synthesis, (2002) 12, 130.
3-Acyldihydrofuran-2(3H)-ones can react with hydrazines as masked β-oxo acid derivatives in the presence of sodium ethoxide. Under the influence of a base, the furan ring opens to form β-oxo ester 292, which on treatment with hydrazines gives 4-(2-hydroxyalkyl)pyrazol-5-ols 293 (Scheme 168). This method is closely related to the synthesis of pyrazoles from β-oxo esters due to the intermediacy of 292. Pyrazole derivatives can also be obtained directly from 3-acyldihydrofuran-2(3H)-ones and hydrazines. In this case, the reaction can be explained by initial formation of the hydrazone followed by “ring-switching” transformation into the pyrazole derivative 293.[616–618]
Meeeee 888 8-(8-Meeeeeeeeeee)eeeeeee-8-eee eeee 8-Meeeeeeeeeeeeeee-8(8M)-eeee eee Meeeeeeeee[888–888]
M8 | M8 | M8 | M8 | Meeee | Meeee (%) | Mee |
---|---|---|---|---|---|---|
Me | M | M | M | M | 88 | [888] |
Me | M | M | 8-Mee | M | 88 | [888] |
Me | M | M | 8-MeM8M8 | M | 88 | [888] |
Me | M | M | 8,8-Me8M8M8 | M | 88 | [888] |
Me | M | M | M | M | 88 | [888] |
Me | Me | M | M | M | 88 | [888] |
Me | M | M | M | M | 88 | [888] |
Me | M | M | M | M | 88 | [888] |
Me | M | M | Me | M | 88 | [888] |
Meeeeeeeeeeeee ee 8-eeeee-8-eeeeeee-8-eeeeeeeeeeee eeee 8-eeeee-8-eeeeeeee-8-eeeeeeeeeeeeeee 888 (Meeeee 888).[888]
Meeeee 888 8-Meeee-8-eeeeeeee-8-eeeeeeeeeeeeeee eeee 8-Meeee-8-eeeeeee-8-eeeeeeeeeeee eee Meeeeeeee[888]
Meeeeeeeeeee Meeeeeeee
8-(8-Meeeeeeeeeee)-8-eeeeee-8M-eeeeeee-8-ee (888, M8 = Me; M8 = M8 = M8 = M); Meeeeee Meeeeeeee:[888]
88% Me eeeeeeeee eeeeeee (88 e, 8.8 eee) eee eeeeee eeeee ee 8-eeeeeeeeeeeeeeeeee-8(8M)-eee (88 e, 8.8 eee). Mee eeeeeee eee eeeeee eee eee eeeeeeeeeee eeeeeeeee ee eeeeeeeeee; eeeee: 88%; ee 888.8–888°M.
8-Meeee-8-eeeeeeee-8-eeeeee-8M-eeeeeeee (888, M8 = Me); Meeeeee Meeeeeeee:[888]
M eeeeeee ee 8-eeeeeee-8-eeeee-8-eeeeeeeeeee (8.888 e, 8 eeee) eee eeeeeeeee eeeeeee (8.8 e, 88 eeee) ee eeeeeeee eeeeee (8 eM) eee eeeeee ee 888°M eee 8 e. Meeeee eee eeeeee eeeeeeeeeeeeee (eeeeee/MeMMe) eeee eee eeeeeee: eeeee: 88%.
References
[616] | Meeeeeee, M. M.; Meeeee, M. M., M. Me. Meee. Mee., (8888) 88, 8888. |
[617] | Meeeeee, M.; Meee, M. M. M., Meee.-Mee., (8888) 888, 888. |
[618] | Meeeeee, M.; Meeee, M., Meee. Mee., (8888) 88, 8888. |
[619] | Meeee, M.; Meeeeee, M.; Meeee, M.; Meeeee, M., M. Mee. Meee., (8888) 88, 8888. |
Meeeeee Meeeeeeeeee
- 8.Meeeee-Meee, (8888) M 8e, 888.