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Afarinkia, K.; Vinader, V., Science of Synthesis, (2003) 14, 300.
Oxidation of 2-(hydroxymethyl)furans, e.g. 57, with a variety of oxidizing agents affords 6-hydroxy-2H-pyran-3-ones, e.g. 58, which can then undergo rearrangement to afford 4H-pyran-4-ones (see Section 14.3.3.2.2) or can be manipulated to afford 2H-pyran-2-ones. The bulk of the methods reported to date use this methodology for the preparation of 4H-pyran-4-ones, which will be discussed later (Section 14.3.3.2.2). However, there are examples of the preparation of 2H-pyran-2-ones in the literature (Scheme 51).[181] Oxidation of 57 (R1 = H) with singlet oxygen affords 6-hydroxy-2H-pyran-3-one 58 (R1 = H), which is first oxidized and then reduced to afford 59. Then, by elimination (see Section 14.3.1.3.1), 59 affords a 6-substituted 2H-pyran-2-one. Since controlled oxidation of furans can be problematic, the choice of oxidizing agent for this reaction is significant. For instance, although oxidation of 57 (R1 = Me) with pyridinium chlorochromate affords 6-hydroxy-2H-pyran-3-one 58 (R1 = Me), the same reagent does not work for the lower homologue 57 (R1 = H).
Meeeee 88 Meeeeeeee ee Meeeee ee 8M-Meeee-8-eeee[888]
Meeeeeeeeeee Meeeeeeee
8-Meeeeee-8M-eeeee-8-eee (88, M8 = M88M88); Meeeeee Meeeeeeee:[888]
M eeee ee MeM8 (8.88 e, 8.8 eeee) ee MeMM (8 eM) eee eeeee eeeeeeee ee e eeee ee 8-eeeeeee-8-eeeeeee-8M-eeeee-8-eee (88; 8.8 e, 8.88 eeee) ee MeMM (8 eM). Meeee 8 e eee eeeeeee eee eeeeee eeee M8M eee eee eeeeeee eee eeeeeeeee eeee Me8M. Mee eeeeeeee eeeeeeee eeee eeeeee eeee eee. ee MeMMM8 eee eeee eeeee. Meeeeeeeeee ee eeeeeee eee eeeeeeeeeeeeee (eeeeee eee, MeMMe/eeeeee 8:88) eeeeeeee 8-eeeeeeeeeeee-8,8-eeeee ee e eeeee; eeeee: 88 ee (88%); ee 88–88°M.
8-Meeeeeeeeeee-8,8-eeeee (8.8 e, 8.88 eeee) eee eeeeeeeee ee e 8.8 M eeee ee MeMe8•8M8M (8.8 eM, 8.88 eeee) ee MeMM, eee MeMM8 (88 ee, 8.88 eeee) eee eeeee eeee 8 eee. Meeee 88 eee eee eeeeeee eee eeeeee eeee M8M eee eee eeeeeee eee eeeeeeeee eeee Me8M. Mee eeeeeeee eeeeeeee eeee eeeeee eeee eee. ee MeMMM8 eee eeee eeeee. Meeeeeeeeee ee eee eeeeeee eee eeeeeeeeeeeeee (eeeeee eee, MeMMe/eeeeee 8:8) eeeeeeee 8-eeeeeee-8-eeeeeee-8,8-eeeeeeeeeeee-8-eee (88) ee e eeeee; eeeee: 88 ee (88%); ee 88–88°M.
MeMe (8.88 e, 8.8 eeee) eee eeeee ee e eeee ee 8-eeeeeee-8-eeeeeee-8,8-eeeeeeeeeeee-8-eee (8.8 e, 8.88 eeee) ee eeeeeeee (8 eM) eeeeeeeeee ee 8–8°M. Meeee eeeeeeee eeeeeeeee ee ee, eee eeeeeee eee eeeeee eeee M8M eee eee eeeeeee eee eeeeeeeee eeee Me8M. Mee eeeeeeee eeeeeeee eeee eeeeee eeee 8 M MMe eee eeee eeee eee. ee MeMMM8. Meeeeeeeeee ee eee eeeeeee eee eeeeeeeeeeeeee (eeeeee eee, MeMMe/eeeeee 8:8) eeeeeeee 8-eee-8-eeeeeee-8,8-eeeeeee-8M-eeeee-8-ee eeeeeeeeeeeeeeee ee e eeeee; eeeee: 888 ee (88%); ee 88–88°M.
M eeee ee eeee eeeeeeee (88 ee, 8.88 eeee) eee eeeeeeee ee Me8M (8 eM) eee 88 e. Meeee eeeeeeeeeee ee eee eeeeeee eee eeeeeee eee eeeeeeeee eeee Me8M. Mee eeeeeeee eeeeeeee eeee eeeeee eeee 8 M MMe eee eeee eeee eee. ee MeMMM8. Meeeeeeeeee ee eee eeeeeee eee eeeeeeeeeeeeee (eeeeee eee, MeMMe/eeeeee 8:8) eeeeeeee 88 ee e eeeee; eeeee: 88 ee (88%); ee 88–88°M.
References
[181] | Mee, M.-M.; Meee, M.-M., Meeeeeeeeeee, (8888) 88, 8888. |
Meeeeee Meeeeeeeeee
- 8.Meeeee-Meee, (8888) M 8-8, 888.
- 8.Meeeee-Meee, (8888) M 88e8, 888.