Chemical Equilibrium between Five- and Six-Membered Nitrogen Heterocycles.
نویسندگان
چکیده
منابع مشابه
Ultrasonic-assisted Synthetic Improvement of Fluorinated Five- and Six-membered Triazolotriazine and Triazinophthalazine Heterocycles
In this investigation a simple synthetic method for the synthesis of trifluoromethyl-1H-benzo[e][1,2,4]triazolo[1,2-a][1,2,4]triazine-1,3(2H)-diones and (trifluoromethyl)benzo [5,6][1,2,4]triazino[1,2-b]phthalazine-8,13-diones has been developed using urazole or phthalazine and aceteimidoyl chloride derivatives at room temperature under ultrasound irradiations. In the comparison to the conventi...
متن کاملRecent developments in the synthesis of five- and six-membered heterocycles using molecular iodine.
Heterocyclic scaffolds represent the key structural subunits of many biologically active compounds. Over the last few years iodine-mediated reactions have been extensively studied due to their low cost and eco-friendliness. This Review covers advances in the field of iodine-mediated synthesis of heterocyclic compounds since 2006, especially with an emphasis on mechanisms of ring formation. In t...
متن کاملRegioselectivity and tautomerism of novel five-membered ring nitrogen heterocycles formed via cyclocondensation of acylthiosemicarbazides.
A series of 1-acyl-4-phenyl/(acridin-9-yl)thiosemicarbazides 3, including four new compounds, were prepared in order to study substituent effects on cyclization reactions with oxalyl chloride (producing imidazolidine-4,5-diones 4), dimethyl acetylenedicarboxylate (to give thiazolidin-4-ones 7 and 8) and autocondensation under alkaline conditions (to yield 1,2,4-triazoles 9). A positional isomer...
متن کامل2-Hetaryl-1,3-tropolones based on five-membered nitrogen heterocycles: synthesis, structure and properties
A series of derivatives of 2-hetaryl-1,3-tropolone (β-tropolone) was prepared by the acid-catalyzed reaction of 2-methylbenzoxazoles, 2-methylbenzothiazoles and 2,3,3-trimethylindoline with 3,4,5,6-tetrachloro-1,2-benzoquinone. The molecular structures of the three representative compounds were determined by X-ray crystallography. In crystal and (as shown by the DFT PBE0/6-311+G** calculations)...
متن کاملTautomerism in Five-membered Nitrogen Heterocycles. A Test of the Reliability of Semiempirical (AMI, PM3, MNDO) Quantum Chemical Methods
The reliability of three popular semiempirical quantum chemical methods (AMI, PM3, MNDO) for the treatment of tautomeric equilibria is tested in a series of five-membered nitrogen heterocycles. The known flaw of M N D O to overestimate the stability of compounds with two or more adjacent pyridine-like lone pairs is also present in AMI and to a somewhat lesser extent in PM3. Tautomeric species d...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Acta Chemica Scandinavica
سال: 1972
ISSN: 0904-213X
DOI: 10.3891/acta.chem.scand.26-4049