Synthesis of 4-substituted 8-amino-4,5-dihydro-3H-pyrrolo[3,4-f]-1,3,5-triazepin-6-ones and 5-amino-2-aryl-4-(1-aryl-5-alkylideneaminoimidazol-4-yl)1,3-oxazoles
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“…Examples of stable 5-aminooxazoles are essentially limited to those bearing an electron-withdrawing functionality at the 4-position, typically a cyano group, [5][6][7][8][9] an amide, 10,11 or an additional heterocycle. [12][13][14] In order to resolve this difficulty, we recently reported 15 a preparation of N-Boc compound 2a via phosgene-mediated cyclization of R-acylaminonitrile 3a, followed by trapping with tert-butyl alcohol (Scheme 1). This Boc-protected intermediate served as a suitable precursor to a library of 2,4-diphenyloxazole-5-amides that were evaluated for their antiprion activity.…”
Section: Introductionmentioning
confidence: 99%
“…Particular difficulty in accessing target compounds 1 is presented by the general instability of free 5-aminooxazoles, which are prone to ring-opening in solution; thus, formation of the amide linkage through derivatization of such intermediates is precluded. Examples of stable 5-aminooxazoles are essentially limited to those bearing an electron-withdrawing functionality at the 4-position, typically a cyano group, − an amide, , or an additional heterocycle. − In order to resolve this difficulty, we recently reported a preparation of N -Boc compound 2a via phosgene-mediated cyclization of α-acylaminonitrile 3a , followed by trapping with tert -butyl alcohol (Scheme ). This Boc-protected intermediate served as a suitable precursor to a library of 2,4-diphenyloxazole-5-amides that were evaluated for their antiprion activity.…”
A highly versatile route to oxazole-5-amides is presented. Conversion of readily accessible oxazole-5-trifluoroacetamides into their Boc-protected 5-aminooxazole derivatives provides intermediates amenable to parallel amide synthesis utilizing a reliable, one-pot, acylation-deprotection procedure. During preparation of the N-Boc compounds from trifluoroacetamides, a competing intramolecular rearrangement giving rise to novel N-(oxazol-5-yl)-2,2,2-trifluoroacetimidates was identified, the extent of which is primarily determined by the choice of reaction conditions.
“…Examples of stable 5-aminooxazoles are essentially limited to those bearing an electron-withdrawing functionality at the 4-position, typically a cyano group, [5][6][7][8][9] an amide, 10,11 or an additional heterocycle. [12][13][14] In order to resolve this difficulty, we recently reported 15 a preparation of N-Boc compound 2a via phosgene-mediated cyclization of R-acylaminonitrile 3a, followed by trapping with tert-butyl alcohol (Scheme 1). This Boc-protected intermediate served as a suitable precursor to a library of 2,4-diphenyloxazole-5-amides that were evaluated for their antiprion activity.…”
Section: Introductionmentioning
confidence: 99%
“…Particular difficulty in accessing target compounds 1 is presented by the general instability of free 5-aminooxazoles, which are prone to ring-opening in solution; thus, formation of the amide linkage through derivatization of such intermediates is precluded. Examples of stable 5-aminooxazoles are essentially limited to those bearing an electron-withdrawing functionality at the 4-position, typically a cyano group, − an amide, , or an additional heterocycle. − In order to resolve this difficulty, we recently reported a preparation of N -Boc compound 2a via phosgene-mediated cyclization of α-acylaminonitrile 3a , followed by trapping with tert -butyl alcohol (Scheme ). This Boc-protected intermediate served as a suitable precursor to a library of 2,4-diphenyloxazole-5-amides that were evaluated for their antiprion activity.…”
A highly versatile route to oxazole-5-amides is presented. Conversion of readily accessible oxazole-5-trifluoroacetamides into their Boc-protected 5-aminooxazole derivatives provides intermediates amenable to parallel amide synthesis utilizing a reliable, one-pot, acylation-deprotection procedure. During preparation of the N-Boc compounds from trifluoroacetamides, a competing intramolecular rearrangement giving rise to novel N-(oxazol-5-yl)-2,2,2-trifluoroacetimidates was identified, the extent of which is primarily determined by the choice of reaction conditions.
“…2,3-Diaminomaleonitrile (DAMN), a tetramer of hydrogen cyanide, was considered as one of the versatile precursors to the synthesis of various types of nitrogen heterocycles such as imidazoles, oxazoles, purines, pyrroles, pyrimidines, pyrazines, diazepines, and triazepines. , Although the reaction of DAMN with various carbonyl compounds has been reported under classical two-component reactions, a careful literature search reveals that the reaction of DAMN with carbonyl compounds and isocyanide under a MCR strategy has not been studied. 1 Synthesis of 1,6-Dihydropyrazine-2,3-dicar- bonitrile Derivatives 4 …”
A novel multi-component synthesis of highly substituted 1,6-dihydropyrazine-2,3-dicarbonitrile derivatives starting from simple and readily available inputs is described. Thus, simply stirring an ethanol solution of 2,3-diaminomaleonitrile, a ketone, and an isocyanide in the presence of a catalytic amount of p-toluenesulfonic acid provided highly substituted 1,6-dihydropyrazine-2,3-dicarbonitrile derivatives in good to excellent yields at ambient temperature.
“…Pyrrolo[1,3,5]triazepines 6a-g could be prepared alternatively from imidate 86 by treating with ammonia in good yields (Scheme 15). 52,103 The mechanism of pyrrolo[1,3,5]triazepines synthesis indicated that the intermediates A are not stable in basic solution (Scheme 16). 103 On the other hand, 1,3,5-triazepine 32 reacted with aliphatic-, aromatic-, and heteroaromatic amines, i.e., hydroxylamine hydrochloride, ethanolamine, 4-aminothiophenol, and 2- 67 The reaction of diaminomaleonitrile 29 and 2,5-hexanedione 91 was attempted under less polar and less acidic conditions to give the unexpected product 5 as the major product (74%) along with trace amounts of 92 (Scheme 18).…”
Section: Synthesis Of Benzo[135]triazepinesmentioning
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