Applications dihydropyrimidines

For example, it was reported in several independent articles that multicomponent treatment of 5-amino-3-methylpyrazles with 1,3-cyclohexandiones and aldehydes under refluxing in EtOH [82, 83], in DMF with methanol [84], or with application of continuous-flow microwave-assisted procedure in DMSO [85] yielded exclusively pyrazoloquinolinones 50 (Scheme 23). On the other hand, the treatment of 3-unsub-stituted 5-aminopyrazoles with cyclic p-diketones or ketosulfones gave mixtures of Hantzsch dihydropyridines 51 and Biginelly dihydropyrimidines 52 in different ratios [86]. 

Deporte-Fety R, Picot M, Amiand M et al. High-performance liquid chromatographic assay with ultraviolet detection for quantiflcation of dihydrofluorouracil in human lymphocytes application to measurement of dihydropyrimidine dehydrogenase activity. J Chromatogr B Biomed Sci Appl 2001 762 203-209. 

As mentioned already, a reaction of enamines with a, 3-unsaturated ketones may be one of the stages of Hantzch synthesis. But in the literature there are a lot of examples of independent applications of a broad set of enamines in dihydropyrimidine syntheses. For example, in [3, 4], a reaction of 3-aminocy-clohex-2-enones 1 with an unsaturated ketone 2 was described which results in a dehydrogenation leading to the formation of a quinoline 3 (Scheme 3.2). 

Z. Lu, R. Zhang, R.B. Diasio, Dihydropyrimidine Dehydrogenase Activity in Human Peripheral Blood Mononuclear Cells and Liver Populations Characteristics, Newly Identified Deficient Patients and Clinical Application in 5-Fluorouracil Chemotherapy , Cancer Res., 53, 5433-5438 (1993). 

Hosseini-Sarvaria (2011b) reported the synthesis of quinoline derivatives (60) by the condensation of 2-aminoaryl ketones (58) with methylene carbonyl compounds (59) catalyzed by nanoflake ZnO as a reusable heterogeneous catalyst under solvent-free conditions involving Friedlander heteroannulation (Scheme 9.14). The employed catalyst was synthesized from zinc acetate dihydrate and urea. It constitutes a simple, environmentally benign, and cost-effective method for the synthesis of quinolines. Tamaddon and Moradi (2013) reported the application of nano-ZnO as a reusable heterogeneous catalyst for the synthesis of Biginelli dihydropyrimidines... 

O. M. Singh, N. S. Devi, / Org. Chem. 2009, 74, 3141-3144. Application of 3-oxodithioesters in domino and multicomponent reactions facile route to dihydropyrimidines and coumarins. 

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