Reversed steric order of reactivity for tert‐butyl and adamantyl‐3‐cyanomethylene‐1,2,4‐triazines

Abstract

Reactions of 2-(6-tert-butyl-5-oxo-4,5-dihydro-1,2,4-triazin-3(2H)-ylidene)-3-oxo-3-R-propanenitriles (R = t-Bu, Ad-1) with tert-butyl bromoacetate gave the corresponding N(2), C(5) O bis-alkylation products. Treatment of the latter with t-BuLi, in the case of R = t-Bu, led to intramolecular condensation at the exocyclic nitrile group. However, in the case of R = Ad-1, the condensation with the sterically more hindered carbonyl group was observed to give diastereomerically pure 8-cyanopyrrolo [1,2-b][1,2,4]triazine-6-carboxylate derivatives. The structures of the isolated products were confirmed by spectral methods and X-ray singlecrystal diffraction.

Synthesis and DFT analysis of non-covalent interactions in crystal structures of 6-R-2-alkoxy-, 2,3-di-, and 2,2,3-tri-tert-butylpyrrolo[1,2-b][1,2,4]triazines

“…The starting pyrrolotriazines 2a,b were synthesized by N,O -bis-alkylation and Thorpe-Ziegler 5- exo -dig type cyclizations [ 17 ] of 2-(6- tert -butyl-5-oxo-4,5-dihydro-1,2,4-triazin-3(2 H )-ylidene)malononitrile 1 [ 18 ] with bromoacetic esters in the presence of potassium hydroxide (Scheme 1 ). Compound 3 was synthesized analogously, by treatment of 1 with isopropyl ( p -bromomethyl)benzoate; this reagent also has the ability to stabilize the negative charge at the methylene moiety due to the π-conjugation [ 16 , 28 ] with the carbonyl group in p -position.…”

“…Recently, we have investigated 2-alkoxy-and alkylthiopyrrolo [1,2,4]triazines with a moderate antimicrobial activity [15] synthesized by recyclization of pyrazolo [5,1c] [1,2,4]triazines and (1,2,4-triazin-3(2H)-ylidene)acetonitriles [16,17]. In continuation of our studies, in the present work, we discuss the X-ray structures of novel 7-amino-3tert-butyl-2-alkoxy-, 2,3-di-tert-butyl-, and 2,2,3-tri-tertbutylpyrrolo [1,2-b] [1,2,4]triazine-8-carbonitriles, as well as the non-covalent interactions and packing modes in the single crystals.…”

CRYSTAL STRUCTURE OF 3-tert-BUTYL- PYRAZOLO[5,1-с][1,2,4]TRIAZINE-3,4-DIYL DICARBOXYLATES

“…Nonetheless, the structural features of hydrogenated azolotriazines still remain poorly studied. We have previously considered the chemical properties and structures of several aromatic and partially saturated azolo[1,2,4]triazines [ 14 - 18 ]. In this work, for the first time we investigated the structures of a series of 3- tert -butyl-3,4-dihydropyrazolo[5,1- с ][1,2,4]triazine-3,4-diyl dicarboxylates by single crystal X-ray diffraction (XRD) and discussed their bond lengths and bond angles together with molecular packings in the crystals.…”