Synthesis of Pyridones

By using l-[methoxycarbonylmethyl]-pyridinium bromide in the solid-phase Krohnke reaction, pyridones were obtained [33]. Six compounds were synthesized, with HPLC-purities between 68% and 76% (A.=214 nm), and yields of the crude products ranging from 71 % to 78% (Fig. 6.23). 

and coworkers reported a Rh-catalyzed oxidative coupling of acrylamides with allcynes to generate 2-pyridones 100 (Eq. (5.97)) [50a]. Both diaryl-or aryl- and alkyl-substituted alkynes were suitable coupling partners for this reaction. The nature of the substituents plays a vital role in this reaction. When the steric hindrance around the olefin or Af-substituent was increased, the reaction afforded N-acyl-indoles as the annulation products. Similarly, Hyster and Rovis reported an improved method for Rh-catalyzed highly regioselective synthesis of pyridones from the annulation of acrylamides and unsymmetrical alkynes [50b]. 

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A highly efficient multicomponent synthesis of pyridones and pyrimidones by a [2 + 2 + 2] strategy [159]... 

Synthesis of pyridone sulfonates as water-tracing compounds. 

The NHC-nickel catalytic system is also useful in the synthesis of pyridones 48. The [2h-2h-2] cycloaddition of diynes 44 and isocyanates 47 affords a wide range of pyridones 48 in excellent yields in presence of [Ni(COD)2]/SIPr catalytic system (Scheme 5.14) [18]. 

Another interesting example of Ugi-Michael process is represented by the synthesis of pyridones 145 (Fig. 28), which originate from an intramolecular domino addition-elimination reaction of the active methylene group proceeding through intermediate 144 [120]. 

The reduction of azetidin-2-ones 297 with LiAlH4 furnished 7-amino alcohols 298 in quantitative yields (Equation 95), which is a key intermediate for the synthesis of pyridones <2002TL3843, 2003T6445, 2003JOC2471>. 

Warner, P., Green, R. C., Gomes, B. and Strimpler, A. M. (1994) Non-peptidic inhibitors of human leukocyte elastase. 1. The design and synthesis of pyridone-containing inhibitors. J. Med. Chem., 37, 3090-3099. 

GUARESKY - THORPE Pyridone Synthesis Synthesis of pyridones from beta diketones and activated amides... 

In another MW-assisted synthesis of pyridones, a ketone, dimethylformamide di-methylacetal 16, and a methylene active nitrile are combined (Scheme 17.12) [44]. 

Pyridines.—Synthesis. A full report on the synthesis of pyridones from acetylenic alcohols and N-cyanopyrrolidine, noted in Volume 7 of Aromatic and Heteroaromatic Chemistry , has appeared.2-Imino-l,2-dihydropyridines (1)... 

Non-Peptidic Inhibitors of Human Leukocyte Elastase. 1. The Design and Synthesis of Pyridone-Containing Inhibitors. 

New synthesis of pyridones using conjugate addition reactions of active methine compounds to alkynyl imines and ketones 06Y251. 

The activating influence of the ring nitrogen provides an important versatility for the synthesis of pyridones, pyridinols, and pyridine ethers, by nucleophilic substitution at the 2- and 4- and even the 3-position. Further, the potential of accomplishing these substitutions via pyridine W-oxides contributes to the scope of this method. 

As mentioned before for the synthesis of pyridones, 5-unsubstimted pyrimidinones 186 can be accessed by utilizing Meldrum s acid 112 as the CH-acidic component (Scheme 13.44) [77], In refluxing ethanol, the desired product could be obtained under catalyst-free conditions in moderate to good yields (51-83%). In DMF at high temperatures with the use of an amino-functionaUzed highly porous MCM-41 catalyst, the yields could be increased, as reported by Mirza-Aghayan et al. [78],... 

SYNTHESIS OF PYRIDONES AND RELATED HETEROCYCLES 4.4.1 Intermolecular Reactions... 

The approach to camptothecin by Danishefsky et alP revolves arpund an interesting synthesis of pyridones via nucleophilic addition to 1,3-dicarbethoxy allene. The C ring of camptothecin has been established by a Dieckmann closure followed by attachment of the quinoline ring using the Friedlander synthesis. Construction of ring E gives desoxycamptothecin, which readily undergoes oxidation to camptothecin. 

Both BLametani and coworkers 61) and Liao et al. 63) have described synthesis of pyridone (72) which now has the D-ring oxygen functionality differentiated The former research group began with a,P-unsaturated ketone (70) the latter group prepared and utilized diketone (71) (Scheme 8), and described subsequent conversion of product (72) to chloro-pyridine (73). 

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