In this study, we report the development of efficient synthetic strategies for the preparation of novel 2'-carboxyl isoflavones and their recyclization products, pyrazoles and oxazoles. Utilizing ...readily accessible starting materials and mild reaction conditions, the synthesis affords valuable compounds with good to excellent yields. The presence of diverse functional groups, including hydroxyl, carboxyl, and carboxamido moieties, renders these molecules attractive for biological screening and targeted structural modifications. This work unveils new avenues for the design of compounds exhibiting a wide range of beneficial properties and opens new opportunities for future research into intramolecular interactions of proximal functional groups.
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•A series of (spiro)pyranocoumarin oximes were successfully subjected to Beckmann rearrangement in the presence of PPA.•The rearrangement led to the efficient formation of unusual ...imines as major products via 2,3-alkyl migration.•The expected lactams were obtained as minor products with insignificant yields via 1,2-alkyl migration.•These findings demonstrate a new approach for the selective synthesis of complex and diverse imines with potential applications in synthetic organic chemistry and medicinal chemistry.
This paper presents the successful implementation of Beckmann rearrangement on a series of (spiro)pyranocoumarin oximes in polyphosphoric acid (PPA) medium. The method demonstrated excellent proficiency in the synthesis of unexpected imines as major products and amides as minor products. The labeled 15NH2OH·HCl control experiment yielded oxime and rearrangement products that incorporated the 15N label. Furthermore, we have proposed a possible rearrangement mechanism. NMR spectroscopy data (correlation HMBC and 15N NMR) confirmed the structure of the synthesized products. These findings provide a new and efficient approach for constructing complex imines with diverse applications in synthetic organic chemistry.
The aminomethylation of hydroxylated isoflavones with 2-aminoethanol, 3-amino-1-propanol, 4-amino-1-butanol, and 5-amino-1-pentanol in the presence of excess formaldehyde led principally to ...9-(2-hydroalkyl)-9,10-dihydro-4H,8H-chromeno8,7-e1,3-oxazin-4-ones 4 and/or the tautomeric 7-hydroxy-8-(1,3-oxazepan-3-ylmethyl)-4H-chromen-4-ones 5. The ratio of these tautomers was dependent on solvent polarity, electronic effects of aryl substituents in the isoflavone and the structure of the amino alcohol. NMR studies confirmed the interconversion of tautomeric forms.
The regioselective condensations of various 7‐hydroxyisoflavonoids with bis(N,N‐dimethylamino)methane in a Mannich reaction provided C‐8 N,N‐dimethylaminomethyl‐substituted isoflavonoids in good ...yield. Similar condensations of 7‐hydroxy‐8‐methylisoflavonoids led to the C‐6‐substituted analogs. Thermal eliminations of dimethylamine from these C‐6 or C‐8 N,N‐dimethylaminomethyl‐substituted isoflavonoids generated ortho‐quinone methide intermediates within isoflavonoid frameworks for the first time. Despite other potential competing outcomes, these ortho‐quinone methide intermediates trapped dienophiles including 2,3‐dihydrofuran, 3,4‐dihydro‐2H‐pyran, 3‐(N,N‐dimethylamino)‐5,5‐dimethyl‐2‐cyclohexen‐1‐one, 1‐morpholinocyclopentene, and 1‐morpholinocyclohexene to give various inverse electron‐demand Diels–Alder adducts. Several adducts derived from 8‐N,N‐dimethylaminomethyl‐substituted isoflavonoids displayed good activity in the 1–10 μm concentration range in an in vitro proliferation assay using the PC‐3 prostate cancer cell line.
Thermally generated ortho‐quinone methides from Mannich bases of 7‐hydroxyisoflavones or from 8‐methoxymethyl‐ or 8‐hydroxymethyl 7‐hydroxyisoflavones trapped a variety of electron‐rich dienophiles to give various inverse electron‐demand Diels–Alder adducts in good yields. Selected adducts displayed good activity in a proliferation assay using the PC‐3 prostate cancer cells.
The propensity of cyclic carboxylic anhydrides to undergo ring‐opening was exploited in a reaction with 2'‐hydroxy‐α‐heteroarylacetophenones leading to the formation of chromones. New simple method ...was developed for the synthesis of 2‐(ω‐carboxyalkyl)‐3‐heteroarylchromones without protecting either the phenolic or the carboxylic groups. Treatment with hydrazine led to the formation of 3(5)‐(ω‐carboxyalkyl)‐5(3)‐(2,4‐dihydroxyphenyl)‐4‐heteroarylpyrazoles.
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•Efficient approach to enaminoketones of 2′-carboxamidodeoxybenzoins in good yields.•Efficient approach to otherwise not readily obtainable 3-aryl-4-formylisocoumarins.•Readily ...available reagents, simple procedures, and short reaction times.•N,N-Dimethylformamide dimethyl acetal serves both as a carbon source and solvent.
The efficient synthesis of enaminoketones of 2′-carboxamidodeoxybenzoins and subsequent transformation into 1-oxo-3-aryl-1H-isochromene-4-carbaldehydes via an intermolecular cyclization under weakly acidic conditions has been demonstrated. Mild reaction conditions, a simple work-up procedure, short reaction times and high yields are the advantages of the presented method.
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All six possible stereoisomers of calix4arenes with four different substituents on the lower rim of the macrocycle have been synthesized by stepwise alkylation of the hydroxyl groups ...of tert-butylcalix4arene using (R)- or (S)-1-phenylethylamide groups as chiral auxiliaries. They form three enantiomeric pairs, as confirmed by the values of their specific rotation.
6-Oxyindan-1-ones with amino acid fragments Shilin, Serhiy; Lenko, Illya; Shablykina, Olga ...
French-Ukrainian journal of chemistry,
2018, Letnik:
6, Številka:
2
Journal Article
Recenzirano
Odprti dostop
New indan-1-one derivatives (8 examples) with amino acid fragments were synthesized through the N-acylation of the amino acids by 2-(3-oxo-2,3-dihydro-1H-inden-5-yloxy)acetic acid using the method of ...activated N-hydroxysuccinimide esters. To obtain corresponding methyl esters (2 examples) two ways were possible: the N-acylation of the amino acid methyl esters by 2-(3-oxo-2,3-dihydro-1-inden-5-yloxy)acetic acid through the activated imidazole derivatives or methylation of the carboxylic function of preformed N-{(1-oxoindan-6-yl)oxyacetyl}amino acids.
The aminomethylation of hydroxylated isoflavones with 2-aminoethanol, 3-amino-1-propanol, 4-amino-1-butanol, and 5-amino-1-pentanol in the presence of excess formaldehyde led principally to ...9-(2-hydroalkyl)-9,10-dihydro-4
H
,8
H
-chromeno8,7-
e
1,3-oxazin-4-ones
4
and/or the tautomeric 7-hydroxy-8-(1,3-oxazepan-3-ylmethyl)-4
H
-chromen-4-ones
5
. The ratio of these tautomers was dependent on solvent polarity, electronic effects of aryl substituents in the isoflavone and the structure of the amino alcohol. NMR studies confirmed the interconversion of tautomeric forms.
Aminomethylation of 7-hydroxy isoflavones with C
2
-C
5
ω-aminoalcohols led to tautomers
4
and
5
that were interconverted as confirmed by NMR studies.
New functionalized derivatives of 8,8,10-trimethyl-4-phenyl-7,8-dihydro-2
H
,6
H
-pyrano3,2-
g
-chromene-2,6-dione – analogues of the natural compound graveolone – possessing hydrazine, ...hydroxylamine, and thiosemicarbazide residues were synthesized and their reactions with acetic anhydride were studied. The structure of the obtained compounds was confirmed by NMR spectroscopy.
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