Abstract
This study describes the simple synthesis of new (quinazolin-4-ylamino) methylphosphonates via microwave irradiation. Substituted-2-aminobenzonitrile reacted with 1,1-dimethoxy-N,N-dimethylmethanamine at a reflux condition to obtain N′-(substituted-2-cyanophenyl)-N,N-dimethylformamidine (1). The subsequent reaction of this intermediate product with α-aminophosphonate (2) in a solution containing glacial acetic acid in 2-propanol through microwave irradiation resulted in the formation of (quinazolin-4-ylamino)methyl-phosphonate derivatives 3a to 3x, which were unequivocally characterized by the spectral data and elemental analysis. The influence of the reaction conditions on the yield of 3a was investigated to optimize the synthetic conditions. The relative optimal conditions for the synthesis of 3a include a 1:1 molar ratio of N′-(2-cyanophenyl)-N,N-dimethylformamidine to diethyl amino(phenyl)methylphosphonate and a 4:1 volume ratio of isopropanol to HOAc in the solvent mixture, at a reaction temperature of 150 °C, with a microwave power of 100 W and a corresponding pressure of 150 psi for 20 min in the microwave synthesizer. The yield of 3a was approximately 79%, whereas those of 3b to 3x were approximately 77% to 86%. Some of the synthesized compounds displayed weak to good anti-Tobacco mosaic virus (TMV) activity.
Highlights
This study describes the simple synthesis of new methylphosphonates via microwave irradiation
Substituted derivatives of α-aminophosphonates exhibit a wide range of bioactivities [11,12,13,14,15], incorporating this pharmacaphore into the parent quinazoline unit may elicit synergistic effects in the design of lead structures with potent antiviral activity for plants
Microwave technology was applied to the synthetic reaction to shorten the reaction time and increase the yields ofmethylphosphonate derivatives (3)
Summary
This study describes the simple synthesis of new (quinazolin-4-ylamino) methylphosphonates via microwave irradiation. Substituted derivatives of α-aminophosphonates exhibit a wide range of bioactivities [11,12,13,14,15], incorporating this pharmacaphore into the parent quinazoline unit may elicit synergistic effects in the design of lead structures with potent antiviral activity for plants. Based on this concept, we planned to simultaneously synthesize novel compounds containing α-aminophosphonates and chloroquinazolines (3). It requires long reaction times, poor yield, and the sensitive nature of 4-chloroquinazoline, accompanied by a complicated route to access the desired product through the classic mode, has motivated us to investigate alternative methodologies [16]
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