Synthesis of new 4,5,6,7‐tetrahydro‐3H‐imidazo[4,5‐c]pyridine derivatives

The synthesis of new ligands for the H₃ histamine receptor is described. These new compounds are spinacine derivatives obtained by alkylation or Michael reaction at C6 position.     

Synthesis of 1,2,5,6‐/1,2,3,6‐tetrahydropyridinyl‐tetrahydro‐cyclopentaisoxazole derivatives

Fused tetrahydrocyclopenta‐isoxazoles were synthesized by 1,3‐dipolar cycloaddition reactions with pyridinealdoxime or tetrahydropyridinealdoxime and cycloalkenes.     

1H and 13C NMR assignments of four series bioactive pyrido[4,3‐d]pyrimidine derivatives

The complete ¹H and ¹³C NMR assignments of four series pyrido[4,3‐d]pyrimidine derivatives were achieved by combination of one and two‐dimensional NMR experiments, and the NMR signals of these compounds were analyzed and compared. Copyright © 2012 John Wiley & Sons, Ltd.     

NMR spectroscopic characterization of new 2,3‐dihydro‐1,3,4‐thiadiazole derivatives

The ¹H and ¹³C NMR resonances of twenty‐seven 2,2‐dimethyl‐5‐(2‐nitrophenyl‐5‐substituted)‐2,3‐dihydro‐1,3,4‐thiadiazoles, and twenty‐seven 3‐acyl‐5‐(2‐amino‐5‐substituted)‐2,2‐dimethyl‐2,3‐dihydro‐1,3,4‐thiadiazoles were assigned completely using the concerted application of one‐dimensional and two‐dimensional experiments (DEPT, HMQC and HMBC). NOESY experiments, X‐ray crystallography and conformational analysis confirm the preferred conformation of these compounds. Copyright © 2012 John Wiley & Sons, Ltd.     

A simple one‐pot synthesis of 1,2,3,4‐tetrahydro‐2‐thioxopyrimidine derivatives

5‐Benzoyl‐4‐(substituted phenyl)‐6‐phenyl‐1,2,3,4‐tetrahydro‐2‐thioxopyrimidines ( 4a‐d ) were synthesized using the Biginelli three component cyclocondensation reaction of an appropriate β‐diketone, arylaldehyde, and thiourea in acetic acid under reflux condition in approximately 52‐65% yields. The acetylation of compounds 4a‐d gave 3‐acetyl thioxopyrimidine derivatives 5a‐d . Also, pyrimidothiazine compounds 6a‐d were prepared by a simple one‐pot condensation reaction of starting pyrimidine derivatives 4a‐d and 3‐bromopropionic acid. The structures of compounds were characterized on the basis of elemental analyses, IR, ¹H and ¹³C‐NMR spectra.     

1H and 13C NMR signal assignments of some new N,N′‐diacyl proflavine derivatives

The complete ¹H and ¹³C NMR signal assignments of 23 new N,N′‐diacyl proflavine derivatives were achieved using one‐ and two‐dimensional experiments (DEPT, HMQC and HMBC). Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis of 2‐amino‐7,8‐dihydro‐6(5H)‐quinazolinone, 2,4‐diamino‐7,8‐dihydro‐6(5H)‐quinazolinone, 5,6,7,8‐tetrahydro‐2,6‐quinazoline‐diamine and 5,6,7,8‐tetrahydro‐2,4,6‐quinazolinetriamine derivatives

N‐(2‐Amino‐5,6,7,8‐tetrahydro‐6‐quinazolinyl)acetamide ( 9 ) and N‐(2,4‐diamino‐5,6,7,8‐tetrahydro‐6‐quinazolinyl)acetamide ( 6 ) were synthesized from N‐(4‐oxocyclohexyl)acetamide ( 5 ) as novel peptidomimetic building blocks. With similar purpose, N‐(6‐oxo‐5,6,7,8‐tetrahydro‐2‐quinazolinyl)acetamide ( 18 ) and N‐[2‐(acetylamino)‐6‐oxo‐5,6,7,8‐tetrahydro‐4‐quinazolinyl]acetamide ( 14 ) were prepared from cyclohexane‐1,4‐dione monoethylene ketal ( 11 ).     

NMR and conformational studies of new 5‐phenylpyrrole‐carboxamide derivatives

The ¹H and ¹³C NMR resonances of 22 5‐(5‐substituted‐2‐nitrophenyl)‐1H‐pyrrole‐2‐carboxamides, 22 5‐(5‐substituted‐2‐aminophenyl)‐1H‐pyrrole‐2‐carboxamides, and 9 5‐phenyl‐1H‐pyrrole‐2‐carboxamides were assigned completely using the concerted application of one‐ and two‐dimensional experiments (DEPT, gs‐HMQC and gs‐HMBC). NOE studies and conformational analysis confirm the preferred conformations of such compounds. Copyright © 2009 John Wiley & Sons, Ltd.     

1H and 13C NMR assignments of bioactive indeno[1,2‐b]indole‐10‐one derivatives

The complete ¹H and ¹³C assignments of eight bioactive indeno[1,2‐b]indole‐10‐one derivatives were accomplished by the combined use of one‐dimensional and two‐dimensional NMR experiments. Copyright © 2013 John Wiley & Sons, Ltd.     

Synthesis and biological activities of novel chiral fluorinated β‐carboline derivatives

A series of unreported chiral β‐carbolines 4 with trifluoromethyl group at position‐1 and chiral carboxamide chains or amino acid ester chains at position‐3 has been designed and synthesized. The results of bioassay in vitro show that compounds 4e, 4i and 4k show 78.8%, 84.0% and 78.9% inhibition on monoamine oxidase, in 1 mmol/L, respectively, and compound 4e also exhibit 60.9% inhibitory activity on tumor lung cell A‐549 in 10^?5 mmol/L. In view of different configuration, the inhibitory activity on monoamine oxidase of S‐enantiomer of the target compound is better than that of R‐enantiomer.     

Semi‐synthesis and NMR spectral assignments of flavonoid and chalcone derivatives

Previous investigations of the aerial parts of the Australian plant Eremophila microtheca and Syzygium tierneyanum resulted in the isolation of the antimicrobial flavonoid jaceosidin ( 4 ) and 2′,6′‐dihydroxy‐4′‐methoxy‐3′,5′‐dimethyl chalcone ( 7 ), respectively. In this current study, compounds 4 and 7 were derivatized by acetylation, pivaloylation, and methylation reactions. The final products, 5,7,4′‐triacetoxy jaceosidin ( 10 ), 5,7,4′‐tripivaloyloxy jaceosidin ( 11 ), 5,7,4′‐trimethoxy jaceosidin ( 12 ), 2′,6′‐diacetoxy‐4′‐methoxy‐3′,5′‐dimethyl chalcone ( 13 ), 2′‐hydroxy‐4′‐methoxy‐6′‐pivaloyloxy‐3′,5′‐dimethyl chalcone ( 14 ), and 2′‐hydroxy‐4′,6′‐dimethoxy‐3′,5′‐dimethyl chalcone ( 15 ) were all fully characterized by NMR and MS. Derivatives 10 and 13 have been previously reported but were only partially characterized. This is the first reported synthesis of 11 and 14 . The natural products and their derivatives were evaluated for their antibacterial and antifungal properties, and the natural product, jaceosidin ( 4 ) and the acetylated derivative, 5,7,4′‐triacetoxy jaceosidin ( 10 ), showed modest antibacterial activity (32–128 µg/ml) against Staphylococcus aureus strains. Copyright © 2016 John Wiley & Sons, Ltd.     

A facile synthesis of 1‐alkyl‐5‐arylalkoxy‐6‐methoxy‐3,4‐dihydroisoquinolines

1‐Alkyl‐5‐arylalkoxy‐6‐methoxy‐3,4‐dihydroisoquinolines were synthesized by the alkylation of 1‐alkyl‐5‐hydroxy‐6‐methoxy‐3,4‐dihydroisoquinolines with arylalkyl halide in the presence of potassium carbonate. 1‐Alkyl‐5‐hydroxy‐6‐methoxy‐3,4‐dihydroisoquinolines as key precursor prepared from o‐vaniline via 6 steps.     

New P‐ligands: 3‐(ethyl‐phenylphosphinato‐) 1,2,3,6‐tetrahydro‐ and 1,2,3,4,5,6‐hexahydrophosphinine derivatives

The trimethylaluminum‐mediated Michael addition of ethyl phenyl‐H‐phosphinate to 1,2‐dihydrophosphinine oxides ( 1A ) yielded 3‐(EtOPhP(O))‐1,2,3,6‐tetrahydrophosphinine oxides ( 4 ) in a selective manner, as a mixture of only two diastereomers. In the above type of reactions (e.g., in that of 1Aa and Ph₂P(O)H), Me₃Al could not be substituted by microwave irradiation due to low efficiency. Catalytic hydrogenation of the Michael adducts ( 4 ) led to 3‐(EtOPhP(O)‐1,2,3,4,5,6‐hexahydrophosphinine oxides 5 , in the case of P‐phenyl substituent ( 5a ), as a mixture of only two diastereomers, while in the instance of the P‐ethoxy derivative ( 5b ), as a mixture of four isomers. Stereostructure of the products ( 5 ) was substantiated on the basis of analogies and stereospecific NMR couplings. The predominant conformations of compounds 4a , 4b , 5a , and 5b‐1 were determined by HF/6‐31G* calculations. Reduction of P(1)–Ph heterocycles 4a and 5a by phenylsilane resulted in monodeoxygenation to afford P‐ligands 6 and 8 , respectively, that were protected as the corresponding phosphine boranes ( 7 and 9 , respectively). © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:747–753, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20365     

Complete assignment of 1H and 13C NMR spectra of α‐phenylsulfinyl‐N‐methoxy‐ N‐methylpropionamide and some p‐substituted derivatives

The complete assignment of the ¹H and ¹³C NMR spectra of the diastereomeric pairs of some α‐arylsulfinyl‐substituted N‐methoxy‐N‐methylpropionamides with the substituents methoxy, methyl, chloro, nitro is reported. Copyright © 2008 John Wiley & Sons, Ltd.     

2‐Chloro‐4,6‐di­methoxy‐1,3,5‐triazine

The mol­ecules of 2‐chloro‐4,6‐di­methoxy‐1,3,5‐triazine, C₅H₆ClN₃O₂, lie on a crystallographic mirror plane. There is a close contact of 3.180 (3) Å between one of the methyl C atoms and the N atom of a neighboring mol­ecule. Differential scanning calorimetry measurements show that methyl rearrangement does not take place in the solid state, despite the close proximity of the methyl group to the N atom.