5.6- Dihydrooxazolo triazole formation

Dinitro ketone 49 with potassium cyanide provided 5,6-dihydrooxazolo [3,2-/7][l,2,4]triazole 51. Its formation is due to the fact that primary attack by the cyanide anion is not directed at the ring C5 atom but rather at the carbonyl group to give the corresponding cyanohydrin 50 and the subsequent intramolecular displacement of the nitro group gives the final product (Scheme 8) (81 KGS 1403). 

The reaction of 5-bromo-3-nitro-l,2,4-triazole and 3,5-dinitro-l,2,4-triazole with a variety of oxiranes yielded the expected 1-substituted imidazoles, and also resulted in the formation of 5,6-dihydrooxazolo[3,2-6]-s-triazoles upon treatment with base (75CHE612). The proposed pathway involves proton abstraction from the imidazole and subsequent attack of the oxirane on the N-anion followed by cyclization in a concerted fashion (equation 56). 2,4(5)-Dinitroimidazole reacts analogously with oxiranes to give isomeric nitro-imidazo[2,1 -f>]oxazoles in good overall yield (8UMC601). 

---

See also in sourсe #XX -- [ , ]

See also in sourсe #XX -- [ , ]

See also in sourсe #XX -- [ , ]

See also in sourсe #XX -- [ , ]

---