Alternative synthetic routes to N-methyl-1,2,4-triazoline-3,5-dione (MeTAD) and other triazolinedione derivatives

N-Methyl-1,2,4-triazoline-3,5-dione (MeTAD) is a powerful electrophile and a versatile synthetic reagent. In this Letter we describe two methods for the synthesis of N-methylurazole, the direct precursor to MeTAD, on gram scales and in good yields. Both methods provide pure urazole while avoiding the necessity of large scale purification via column chromatography or recrystallization. One of the methods proved to be amenable for the synthesis of derivatives other than N-methyl. (C) 2014 Elsevier Ltd. All rights reserved.