ChemInform Abstract: REACTION OF DIACETYLENE COMPOUNDS WITH BENZYLAZIDE

Abstract

Cycloadditionen äquimolarer Mengen von Benzylazid an die Diacetylene (I) verlaufen regiospezifisch und liefern überwiegend Gemische der 1,5‐ (lH‐NMR‐spektrometrisch bestimmter Anteil 62‐75%) und 1,4‐Isomeren von Alkinylbenzyltriazolen (II), daneben auch Bistriazolyle (III).

“Click” Synthesis of Nonsymmetrical Bis(1,2,3-triazoles)

“…The synthesis of 4-alkynyl-1,2,3-triazoles 5 was itself challenging. Not surprisingly, the thermal cycloaddition of terminal diacetylenes with 1 equiv of benzyl azide resulted in mixtures of 1,4- and 1,5-regioisomers of bis-triazoles together with small amounts of the desired 4-ethynyl-1,2,3-triazole . Tykwinski et al have reported the regioselective trapping of terminal di-, tri-, and tetraynes with benzyl azide to afford alkynyl-, butadiynyl-, and hexatriynyltriazoles in moderate to good yields .…”

“…Not surprisingly, the thermal cycloaddition of terminal diacetylenes with 1 equiv of benzyl azide resulted in mixtures of 1,4-and 1,5-regioisomers of bis-triazoles together with small amounts of the desired 4-ethynyl-1,2,3triazole. 8 Tykwinski et al have reported the regioselective trapping of terminal di-, tri-, and tetraynes with benzyl azide to afford alkynyl-, butadiynyl-, and hexatriynyltriazoles in moderate to good yields. 9 4-Ethynyl-1,2,3-triazoles or their trimethylsilyl-protected counterparts were also prepared as antibacterial agents 10 or tachykinin receptor antagonists.…”

Regioselective Trapping of Terminal Di-, Tri-, and Tetraynes with Benzyl Azide

“…The recent development of procedures for triazole formation through the reaction of terminal alkynes with azides under Cu(I) catalysis and mild conditions seemed ideal for such an application . Several questions, however, presented themselves with respect to the outcome of these reactions, including: (a) Would conditions be sufficiently mild to trap di-, tri-, and tetraynes with an azide for triazole formation? (b) Would the regiochemistry remain consistent with that reported for the reaction of azides with terminal alkynes? , (c) Would multiple additions occur due to the more activated nature of the di-, tri-, or tetrayne substrates? We report herein our preliminary investigations into the trapping of di-, tri-, and tetraynes with benzyl azide under mild conditions, which provide initial answers to the questions above.…”

“…Reaction of azides with terminal alkynes under thermal conditions typically affords a mixture of 1,4- and 1,5-triazole products, whereas reactions with alkynes under Cu catalysis give selectively 1,4-triazoles. , Under thermal conditions, terminal diynes also give a mixture of products, whereas the reaction of bis(trimethylsilyl)butadiyne and -hexatriyne with azides is regioselective . The regiochemistry for triazole products 1 , 3 , and 5 could be inferred from their 1 H NMR spectra, which showed resonances for the triazole ring proton in the expected range of δ 7.47−7.65 . The only exception to this trend is the ynone-substituted 1h , where this signal is shifted downfield to δ 7.81, presumably due to conjugation with the ketone.…”