4,6-Diarylpyrimidin-2(1H)-ones were effectively synthesised by utilising chlorotrimethylsilane (TMSCl) as an efficient promoter in the cyclisation condensation of arylketones, substituted benzaldehydes and urea by a one-pot, threecomponent reaction under air in DMF/CH 3 CN. The clean, mild reaction conditions, operational simplicity and high yields were attractive features of the reaction which enables a facile preparative procedure for building the pyrimidine ring.
Some substituted quinolines were effectively synthesized utilizing chlorotrimethylsilane (TMSCl) as efficient promoter in the cyclization addition of enolizable aldehydes to arylimines under an air atmosphere in DMSO. The clean, mild and ecofriendly process with high yields and a simple workup of the desired compounds are attractive features of the reaction which enables a facile preparation of the quinoline ring.
For many years, the modification of natural steroids has drawn considerable attention from medicinal and synthetic organic chemists. Among them, various derivatives involving chemical modification of the steroidal D ring have shown biologically important properties. 1-4 For example, 3α,5α-17-phenylandrost-16-en-3-ol is a neurosteroid antagonist, 5 which can antagonise selectively the GABA-modulatory and GABA-mimetic effects of 3α,5α-tetrahydroprogesterone and related 5α-pregnane steroids. 5-6 Another important modified D-ring steroid is 3β-acetoxy-17-(pyridin-3-yl)androsta-5,16-diene (abiraterone acetate) which is a potent inhibitor of human cytochrome P450 17 α (steroidal 17α-hydroxylase-C 17,20 -lyase) that has been approved for use together with prednisone or prednisolone, for the treatment of metastatic castration-resistant prostate cancer. 7-8 Due to the pharmacological importance of abiraterone acetate and analogues, a number of methods for the preparation of abiraterone acetate and analogues have been developed. 9-10 The classical preparation of the abiraterone acetate utilised palladium-catalysed cross-coupling reaction between diethyl(3-pyridyl)borane and the 17-enol triflate generated from 3-acetate of dehydroepiandrosterone. The synthesis involved the conversion of the carbonyl at the 17 position of dehydroepiandrosterone acetate to the corresponding enol triflate by treatment with trifluoromethanesulphonic anhydride and 2,6-di-tert-butyl-4-methyl pyridine. 11-12 A similar synthesis comprised sulphonation of the enol of dehydroepiandrosterone acetate with p-toluenesulfonic acid to obtain (3β)acetoxyandrost-5,16-dien-17-yl-p-toluenesulfonate. Coupling with diethyl(3-pyridyl)borane in the presence of bis(tri-Ph phosphine)palladium dichloride as catalyst was then used to generate the product. 13 Another improved method involved replacement of the 17enol triflate by the vinyl iodide of dehydroepiandrosterone in the palladium-catalysed Suzuki cross-coupling step. The vinyl iodide of dehydroepiandrosterone was prepared from the corresponding 17-hydrazone in the presence of iodine and guanidine base. 14-15 On the basis of the above method, Hong and coauthors described an improved preparation of abiraterone acetate using a pyridyl Grignard reagent which was coupled with the vinyl iodide of dehydroepiandrosterone in the palladium catalyst system using either [Pd(dppf)Cl 2 , Pd(PPh 3 ) 4 , PdCl 2 (dppe), Pd/C and Pd(CH 3 CN)Cl 2 ] or nickel catalyst system [Ni(dppp)Cl 2 or NiCl 2 (dppe)]. 16 Wang and coauthors also reported a similar method in which 17-iodoandrosta-5,16-dien-3β-ol was subjected to a Negishi crosscoupling with 3-pyridylzinc bromide obtained by successive reaction of 3-bromopyridine with n-BuLi and ZnBr 2 . This was Green Suzuki coupling reaction for synthesis of abiraterone acetate and its analogues An eco-friendly efficient method was developed for the synthesis of abiraterone acetate and analogues in water-PEG-400 (6:1; v/v) at 75 °C from various arylboronic acids and 17-(trifluoromethanesulfon...
The Michael addition of nitromethane to chalcones promoted by microwave irradiation without solvent afforded 1,3-diaryl-4-nitro-1-butanones in good yield. The products were characterised by IR, 1 H NMR and elemental analysis.
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