✍ Scribed by Martina Brunner; Gerhard Maas; Frank-Gerrit Klärner
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The cycloaddition of organic azides with some conjugated enamines of the 2‐amino‐1,3‐diene, 1‐amino‐1,3‐diene, and 2‐aminobut‐1‐en‐3‐yne type is investigated. The 2‐morpholinobuta‐1,3‐diene 1 undergoes regioselective [3+2] cycloaddition with several electrophilic azides RN~3~ 2 (a, R=4‐nitrophenyl; b, R=ethoxycarbonyl; c, R=tosyl; d, R=phenyl) to form 5‐alkenyl‐4,5‐dihydro‐5‐morpholino‐1__H__‐1,2,3‐triazoles 3 which are transformed into 1,5‐disubstituted 1__H__‐triazoles 4a,d or α,β‐unsaturated carboximidamide 5 (Scheme 1). The cycloaddition reaction of 4‐[(1__E__,3__Z__)‐3‐morpholino‐4‐phenylbuta‐1,3‐dienyl]morpholine (7) with azide 2a occurs at the less‐substituted enamine function and yields the 4‐(1‐morpholino‐2‐phenylethenyl)‐1__H__‐1,2,3‐triazole 8 (Scheme 2). The 1,3‐dipolar cycloaddition reaction of azides 2a–d with 4‐(1‐methylene‐3‐phenylprop‐2‐ynyl)morpholine (9) is accelerated at high pressure (ca. 7–10 kbar) and gives 1,5‐disubstituted dihydro‐1__H__‐triazoles 10a,b and 1‐phenyl‐5‐(phenylethynyl)‐1__H__‐1,2,3‐triazole (11d) in significantly improved yields (Schemes 3 and 4). The formation of 11d is also facilitated in the presence of an equimolar quantity of t__BuOH. The three‐component reaction between enamine 9, phenyl azide, and phenol affords the 5‐(2‐phenoxy‐2‐phenylethenyl)‐1__H‐1,2,3‐triazole 14d.
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## Abstract For Abstract see ChemInform Abstract in Full Text.
The cycloaddition reactions of 1-p-tolyl and 1-benzyl-2,4-diphenyl-1,3-diazabuta-1,3-dienes with a variety of aryl and alkyl isocyanate and isothiocyanate are described. The reaction mechanism is also discussed.
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