4 -Ethynyl-l,2,3-triazoles

Azidocumulenes, which tend to rapid cyclization leading to triazole dalvatives, are available not only by sigmatropic or prototropic rearrangement (see Scheme 5.35), but also by 1,4-elimination of hydrogen chloride from the substrate 291 (Schane 5.37). Thus, the reaction of 291 with sodium hydroxide in methanol gave 4-ethynyl-l,2,3-triazole (295) after aqueous workup. This result was explained by formation of short-lived azidobutatriene (292) followed by ring closure and deprotonation of intermediate 293. When dichloride 290 was treated with a substoichiometric amount of sodium azide and then with sodium hydroxide in methanol, the product 295 was synthesized in a one-pot procedure with 45% yield. 

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See also in sourсe #XX -- [ , , ]

See also in sourсe #XX -- [ , , ]

See also in sourсe #XX -- [ , , ]

See also in sourсe #XX -- [ , , ]

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