The 2-acylcycloalkanones 1a-g and 3a-c, possessing a polyfluoroalkyl group. react with hydroxylamine regio- and stereoselectively to yield 4,5-dihydroisoxazol-5-ols 2a-g and 4a-c, respectively i.e., products of N-addition to the oxo group at the cycloalkane ring (Schemes 1 and 2). The products 2 and 4 can be dehydrated under drastic conditions only (Schemes 3 and 4). The structure of one of the 4,5-dihydroisoxazol-5-ols was confirmed by X-ray crystal-structure analysis.
inhibitors the reaction of 5-amino-1-tert-butyl-1H-pyrrolo-3-carbonitrile with fluorinated 1,3-biselectrophiles was studied. An efficient and convenient synthetical approach to obtain fluorinated pyrrolo[2,3-b]pyridines was developed. tert-Butyl protecting group was successfully cleaved by treating of synthesized pyrrolopyridines with concentrated sulfuric acid.
Syntheses of Novel 4-Polfluoroalkyl-Substituted 5,6-Oligomethylene Pyrimidines
作者:Dmitrii V. Sevenard、Oleg G. Khomutov、Olga V. Koryakova、Valeriya V. Sattarova、Mikhail I. Kodess、Johannes Stelten、Ildiko Loop、Enno Lork、Kazimir I. Pashkevich、Gerd-Volker Röschenthaler
DOI:10.1055/s-2000-8200
日期:——
2-Acylcycloalkanones having polyfluoroalkyl groups react with guanidine, urea, thiourea, methylisothiourea, benzamidine, guanylthiourea, dicyanodiamide, and trifluoroacetylurea by Lewis-acid catalysis to form the corresponding 5,6-oligomethylene pyrimidines. A decrease in the yields along with increase of polyfluoroalkyl substituent length in the molecule of the starting 1,3-diketone was observed in the case of reagents with lower nucleophilicity (urea, thiourea, dicyanodiamide). The pyrimidines obtained from aromatic aldehydes showed E-configuration with respect to the arylidene double bond. Tautomeric structures as a function of the substituent in 2 position in the pyrimidine ring both in liquid and solid state were investigated by X-ray diffraction, IR and NMR spectroscopy.
The 2-acylcycloalkanones 1a-g and 3a-c, possessing a polyfluoroalkyl group. react with hydroxylamine regio- and stereoselectively to yield 4,5-dihydroisoxazol-5-ols 2a-g and 4a-c, respectively i.e., products of N-addition to the oxo group at the cycloalkane ring (Schemes 1 and 2). The products 2 and 4 can be dehydrated under drastic conditions only (Schemes 3 and 4). The structure of one of the 4,5-dihydroisoxazol-5-ols was confirmed by X-ray crystal-structure analysis.