A surprising rearrangement of a carbeneethylene sulfide ylide (original) (raw)
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Tetrahedron, 1997
Levoglucosenone (1,6-anhydro-3,4-dideoxy-P-D-glycero-hex-3-enopyranos-2-ulose) undergoes [4 + 21 addition with cyclopentadiene from the (Y face to give 65% of endo-alkene (2) and 16% of exo-alkene (3) adducts. Reduction of 2 with sodium borohydride gave 53% of the endo alcohol 4, and 39% of the exo alcohol 5. Oxidation of 5 with m-chloroperoxybenzoic acid gave the expected oxirane, whereas 4 gave an alcohol (6) resulting from oxirane ring-opening by HO-2. Reduction of adduct 3 with sodium borohydride gave 74% of the exo alcohol and 22% of the endo alcohol. The structure of 6 was confirmed by X-ray crystallography.
A Versatile Cyclodehydration Reaction for the Synthesis of Isoquinoline and β-Carboline Derivatives
Organic Letters, 2008
The direct conversion of various amides to isoquinoline and β-carboline derivatives via mild electrophilic amide activation, with trifluoromethanesulfonic anhydride in the presence of 2chloropyridine, is described. Low temperature amide activation followed by cyclodehydration upon warming provides the desired products with short overall reaction times. The successful use of nonactivated and halogenated phenethylene derived amides, N-vinyl amides, and optically active substrates are noteworthy. The venerable Bischler-Napieralski reaction offers an important strategy for the synthesis of various azaheterocycles. 1,2 Isoquinolines and β-carbolines, including their reduced derivatives, can be found as substructures in many important natural products, pharmaceuticals, and other fine chemicals. 3 We have reported the syntheses of pyridine 4a and pyrimidine 4b derivatives via the intermolecular condensation of readily available N-vinyl and N-aryl amides 5 with various nucleophiles. Herein we report mild reaction conditions for the Bischler-Napieralski based synthesis of isoquinoline and β-carboline derivatives from readily available amides. During our studies concerning the syntheses of pyridines and quinolines via an intermolecular condensation reaction 4b we observed a competitive intramolecular cyclization reaction in a single case where a Morgan-Walls 6 cyclization pathway was possible. N-Phenethylbenzamide (1 , Table 1) was used to further investigate this intramolecular condensation reaction. Consistent with our observations on amide activation for the intermolecular addition of σor π-nucleophiles, 4 the use of trifluoromethanesulfonic anhydride (Tf 2 O
Synthesis of new pentacyclic diquinothiazines
Journal of Heterocyclic Chemistry, 2007
Reactions of 2,2'-dichloro-3,3'-diquinolinyl sulfide 1 with ammonia derivatives and various primary alkylamines and arylamines proceeded as a thiazine ring closure to form linear annulated pentacyclic 6Hdiquinothiazine 2H and 6-substituted derivatives 2 with alkyl, alkylaryl, aryl and heteroaryl substituents in moderate to good yields. Reaction with 2-chloroethylamine did not stop at the formation of half-mustard derivative 2k but ran to ethylenediquinothiazinium salt 11. 6H-Diquinothiazine 2H was N-alkylated and Narylated to give 6-substituted derivatives 2. The crucial substrate 1 was obtained from other heteropentacenes 3 and 4 via 1,4-dithiin ring opening and further transformations. X-ray analysis of p-nitrophenyldiquinothiazine 2i revealed unexpected planar thiazine ring.
Journal of Molecular Modeling, 2019
Quinolinones and sulfonamides are moieties with biological potential that can be linked to form new hybrid compounds with improved potential. However, there are few hybrids of these molecules reported. In this sense, this work presents a structural description of a new sulfonamide-dihydroquinolinone (E)-2-(2-methoxyphenyl)-3-(3-nitrobenzylidene)-1-(phenylsulfonyl)-2,3 dihydroquinolin-4(1H)-one (DHQ). The molecular structure of DHQ was elucidated by X-ray diffraction, nuclear magnetic resonance and infrared spectroscopy, and both molecular packing and intermolecular interactions were analyzed by Hirshfeld surfaces and fingerprint maps. In addition, theoretical calculations on frontier orbitals, molecular electrostatic potential maps, and assignments were performed. The crystal packing of DHQ was found to be stabilized by a dimer through a weak C-H⋯O interaction along the c axis. Moreover, the structure is stabilized mainly by C-H⋯O and C-H⋯π interactions, since the interaction C25-H25⋯π contributes to a chain formation. The Hirshfeld normalized surface shows that the closest interactions are around the atoms linked to the dimer formation. The calculations indicate that DHQ possesses electrophilic sites near O atoms and depleted electrons around the H atoms. There is a band GAP of 3.29 eV between its frontier orbitals, which indicates that DHQ is more reactive than other analogues published.
Tetrahedron, 2013
2-Amino-3,5-dibromoacetophenone undergoes Vilsmeier reaction with a phosphoryl chlorideedimethylformamide mixture to afford 6,8-dibromo-4-chloroquinoline-3-carbaldehyde. The latter was reacted with arylhydrazine hydrochlorides in ethanol in the presence of triethylamine to afford the corresponding arylhydrazone derivatives. These hydrazones were, in turn, cyclized with ethanolic KOH (5% in ethanol) to afford the corresponding 1-aryl-6,8-dibromo-1H-pyrazolo[4,3-c]quinolines. Suzu-kieMiyaura cross-coupling of these 1-aryl-6,8-dibromo-1H-pyrazolo[4,3-c]quinolines with arylboronic acids afforded novel 1,6,8-triaryl-1H-pyrolo[4,3-c]quinolines.