Rapid microwave-assisted cleavage of methyl phenyl ethers: new method for synthesizing desmethyl precursors and for removing protecting groups
نویسندگان
چکیده
A new microwave-enhanced method for rapid demethylation of methyl phenyl ethers using neat methanesulfonic acid (CH3SO3H) is presented. Using a monomodal microwave cavity, cleavage of anisole (1), used as model compound, to phenol (2) was achieved with high conversions (ca 80%) in very short reaction times (10–20 s). The feasibility of cleaving one or both of two methoxy groups was illustrated with 4-(3-bromoanilino)-6,7-dimethoxyquinazoline (PD153035, 3). High conversions (582%) of 3 were attained with four different conditions (i.e. combination of input effect (35–125W) and time (15 s–2min)). 4-(3-Bromoanilino)-7-hydroxy-6-methoxyquinazoline (4), 4-(3-bromoanilino)-6-hydroxy-7-methoxyquinazoline (5) and 4-(3-bromoanilino)-6,7-dihydroxyquinazoline (6), the possible monoor di-demethylated compounds, were obtained. Methods for rapid demethylations are of interest in radiochemistry for post-labeling deprotections of hydroxyl containing aromatic rings and also provide a more direct route for synthesizing precursor compounds for labeling by alkylation. Copyright # 2002 John Wiley & Sons, Ltd.
منابع مشابه
A Tandem Scalable Microwave-Assisted Williamson Alkyl Aryl Ether Synthesis under Mild Conditions
An efficient tandem synthesis of alkyl aryl ethers, including valuable building blocks of dialdehyde and dinitro groups under microwave irradiation and solvent free conditions on potassium carbonate as a mild solid base has been developed. A series of alkyl aryl ethers were obtained from alcohols in excellent yields by following the Williamson ether synthesis protocol under practical mild condi...
متن کاملA Crystallization-Induced Asymmetric Transformation using Racemic Phenyl Alanine Methyl Ester Derivatives as Versatile Precursors to Prepare Amino Acids
L-Tyrosine and L-Dopa are the precursors in the biological synthesis of amine neurotransmitters. On the other hand, phenylalanine as an aromatic amino acid (AAA) is a precursor in the synthesis of L-Tyrosine and L-Dopa. For some substrates such as amino acids, resolution by the formation of diastereomers offers an attractive alternative. Among different methods in this case, crystallization-ind...
متن کاملOne Step Rapid Synthesis of Nano-Crystalline ZnO by Microwave-Assisted Solution Combustion Method
In this study nano-crystalline ZnO particles were synthesized by microwave-assisted solution combustion method. Zinc nitrate and urea were used as oxidizer and fuel, respectively. The effect of fuel to oxidizer (F/O) ratio on ZnO powder properties was investigated by using different urea/nitrate ratios. X-ray diffractometer, scanning electron microscopy and fourier transform infra-red were used...
متن کاملCLEAVAGE OF ESTERS AND ETHERS WITH SILICA CHLORIDE
Silica chloride converted benzyl or tert-butyl esters to the corresponding acid chlorides and alkyl chlorides. It also converted benzyl or tert-butyl phenyl ethers to the corresponding allcyl chlorides and phenol
متن کاملMicrowave-assisted Synthesis of MgFe2O4-ZnO Nanocomposite and Its Photo-catalyst Investigation in Methyl Orange Degradation
In this work firstly MgFe2O4 nanoparticles were synthesized via a microwave-assisted method. The product was calcinated at 900 ºC for 2h. At the second step zinc oxide shell was synthesized on the ferrite under ultrasonic waves. Properties of the product were examined by X-ray diffraction pattern (XRD), scanning electron microscope (SEM) and Fourier transform infrared (FT-IR) spectroscopy. Vibr...
متن کامل