0000000001312477
AUTHOR
Antal Csámpai
Stereoselective synthesis and application of tridentate aminodiols derived from (+)-pulegone
Abstract A library of tridentate aminodiols, derived from naturally occurring (R)-(+)-pulegone, was synthesized and applied as chiral catalysts in the addition of diethylzinc to benzaldehyde. The reduction of pulegone furnished pulegol, which was transformed into allylic trichloroacetamide via Overman rearrangement of the corresponding trichloroacetimidate. The protected enamine was subjected to dihydroxylation with OsO4/NMO system resulting in a 1:1 mixture of (1R,2R,4R)- and (1S,2S,4R)-aminodiol diastereomers. After the removal of the trichloroacetyl protecting groups, the obtained primary aminodiols were transformed into secondary ones. The regioselectivity of the ring closure of the N-b…
Preparation and Structure of Bicycloalkane-Condensed Aryldiaziridines Accompanied by Pyrimidines
Di-exo- and di-endo-2-aminonorbomane/enemethanamines 1-3, di-exo-oxanorbomene derivative 4 and cis-cyclohexane and trans-4-cyclohexene analogues 5, 6 were reacted with p-chlorobenzaldehyde in the presence of N-bromosuccinimide in dichloromethane. Via the reactions of 1-6, condensed diaziridines 7-12 accompanied by pyrimidine derivatives 13-16 were prepared after isolation with column chromatography. The mechanisms proposed for alternative transformations were supported by DFT calculations. The structures of the new compounds were proved by IR and NMR spectroscopy and, for 7, 9 and 12, also by means of X-ray crystallography.
Preparation and structure of pyrrolo[2,1-b]- and isoindolo[1,2-b][3,1]epoxyquinazolines
Abstract Various γ-oxocarboxylic acids [aroylpropionic acids, cis-2-(4-methylbenzoyl)cyclohexanecarboxylic acid, diendo-3-benzoylbicyclo[2.2.1] heptane-2-carboxylic acid, formylbenzoic acid, methanobenzenecyclooctencarboxylic acid and the cyclopentadiene adduct of 3-trans-(4-methylbenzoyl)acrylic acid] were reacted with diexo-3-aminomethyl-7-oxabicyclo[2.2.1]hept-5-en-2-ylamine 2 to result in condensed pyrroloepoxyquinazolines 3–10. The starting 2 retained the diexo configuration, but cis → trans isomerization took place when cis-2-(4-methylbenzoyl)cyclohexanecarboxylic acid was applied. The structures, including the ring annelations and the position of the aryl group on the new chiral cent…
Isomerization and Application of Aroylnorbornenecarboxylic Acids for Stereoselective Preparation of Heterocycles
When boiled in acidic or basic solution, diendo-3-aroylbicyclo[2.2.1]heptane-2-carboxylic acids (1 and la) isomerize to exo-3-aroylbicyclo[2.2.1]heptane-endo-2-carboxylic acids (2 and 2a). Similar endo→exo and even exo → endo isomerization of the aroyl group occurred when the Diels-Alder product containing a mixture of 3-exo-p-toluoylbicyclo[2.2.1 ]hept-5-ene-2-endo-carboxylic acid (4) and 3-endo-p-toluoylbicyclo[2.2.1]hept-5-ene-2-exo-carboxylic acid (5) was reacted with bifunctional reagents: o-aminothiophenol, 3-amino-1-propanol, 1,4-diaminobutane or diexo-3-hydroxymethylbicyclo[2.2.1]heptane-2-amine. All the reactions yielded mixtures of norbornene diendo- and diexo-fused heterocycles (…
A retro Diels–Alder method for the preparation of pyrrolo[1,2-a]pyrimidinediones from diexo-aminooxanorbornenecarboxamide
Abstract Through the reactions of diexo-3-amino-7-oxanorbornene-2-carboxamide 1 with the oxocarboxylic acids: 4-oxopentanoic acid, p-chlorobenzoylpropionic acid or 2-formylbenzoic acid, the pyrrolo[1,2-a]pyrimidinediones 2 and 3 or pyrimido[1,2-a]isoindoledione 4 were formed on cyclization and thermolysis, when the parent cycles decomposed via the loss of furan to give 2–4 in a retro Diels–Alder reaction. With cis-or trans-2-aroylcyclohexanecarboxylic acids as starting compounds, the 1-aroylhexahydroisoindol-3-ones (5–8) were formed; the phenyl-substituted derivatives gave diastereomeric mixtures. The structures of the new compounds were established by NMR spectroscopy and, for 3 and 6, als…
Preparation and Structures of Isoindolone- or Pyrimidone-Condensed Heterocycles Containing a Hydroxy Group on a Cyclohexane or Norbornane Moiety
With DL-valinol, 3-amino-1-propanol and o-aminothiophenol, aroyl(bi/tri)cyclic lactones 1 and 2 were cy- clized to isoindole- 4-6, 8, 9, pyrimidinone- 10 or thiazepine- 7 condensed heterocycles. The ketal lactone 3 furnished the benzthiazoloisoindole 9 and mixtures of epimeric hydroxyphthalazinoquinazolinones 11 and 12. The structures were es- tablished by means of 1 H and 13 C NMR spectroscopy and in some cases by X-ray crystallography.
CCDC 1470051: Experimental Crystal Structure Determination
Related Article: Tímea Gonda, Zsolt Szakonyi, Antal Csámpai, Matti Haukka, Ferenc Fülöp|2016|Tetrahedron:Asymm.|27|480|doi:10.1016/j.tetasy.2016.04.009
CCDC 1470052: Experimental Crystal Structure Determination
Related Article: Tímea Gonda, Zsolt Szakonyi, Antal Csámpai, Matti Haukka, Ferenc Fülöp|2016|Tetrahedron:Asymm.|27|480|doi:10.1016/j.tetasy.2016.04.009