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Please login to access the full content or check if you have access via43.8.2.6.5 Method 5: Fragmentation of 1,3,4-Oxadiazolidin-2-ones
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Krueger, A., Science of Synthesis, (2008) 43, 543.
Instead of using the tosylhydrazones, epoxy ketones can be transformed into the respective alkynes by way of the spirocyclic 1,3,4-oxadiazolidin-2-ones 165 (X = O).[295,296] In 1978 it was reported that reaction of epoxy ketones 163 to give the semicarbazones 164 and subsequently to yield the spiro compounds 165 proceeds smoothly and the fragmentation yields the desired alkyne (Table 16).[295] Epoxy aldehydes cannot react in this way as they cyclize to 1,3,4-oxadiazol-2-amines instead. In order to further improve the scope of this reaction, 1,3,4-oxadiazolidin-2-imines are also used.
Meeee 88 Meeeeeee ee Meeee Meeeeee Me Meee Meeeeee eee 8,8,8-Meeeeeeeeeeee-8-eeee[888,888]
| Meeeeeee | Meeeeee | Meeeeeeeee | Meeee (%) | Mee |
|---|---|---|---|---|
 |
|
8. eeeeeeeeeeeee eeeeeeeeeeeee, MeMMe, 88°M 8. Me(MMe)8 8. MeMM, eeeeee |
88 | [888] |
| |
|
8. 8-eeeeeeeeeeeeeeeeeee 8. Me(MMe)8 8. eeeeeeee eeeeee, 888°M, 8.8 e |
88 | [888] |
| |
|
8. 8-eeeeeeeeeeeeeeeeeee 8. Me(MMe)8 8. eeeeeeee eeeeee, 888°M, 8.88 e |
88 | [888] |
| |
|
8. 8-eeeeeeeeeeeeeeeeeee 8. Me(MMe)8 8. MeMM8, 888°M, 8 e |
88 | [888] |
| |
|
8. 8-eeeeeeeeeeeeeeeeeee 8. Me(MMe)8 8. eeeeeeee eeeeee, MeMM (eee.), 888°M |
88e | [888] |
e Meee eeeee eeeee.
References
| [295] | MeeMeeeee, M. M.; Meeeeeeee, M., Mee. M. Meee., (8888) 88, 888. |
| [296] | Mee, M.; Meeeee, M. M.; Meeeeee, M.; Meeeee, M.; Meeee, M., Meeee. Meeeee., (8888) 88, 888. |
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