Bicyclization Involving Pseudo-Intramolecular Imination with Diamines

α-Nitro-δ-keto nitriles and α-nitro-δ-keto ester were readily converted to diazabicyclo compounds having vicinal functionality upon treatment with diamines. The keto nitrile attracts the diamine nearby to an acidic hydrogen to cause the pseudo-intramolecular imination which proceeds efficiently without any catalyst at room temperature

Reactive 2-Quinolones Dearomatized by Steric Repulsion between 1-Methyl and 8-Substited Groups

Usual 1-methyl-2-quinolone (MeQone) derivatives are not reactive because of aromatic property in the heterocyclic ring. On the other hand, 8-substituted MeQones have been proved to be highly reactive, which is caused by steric repulsion between the 1-methyl and the 8-substituted groups. When 1-methyl-3,6,8-trinitro-2-quinolone was treated with potassium (or trimethylsilyl) cyanide, cyanation proceeded at the 4-position regioselectively as a result of cine-substitution. This reaction is initiated with addition of cyanide species, and the cyanoquinolone is formed by the protonation of the resultant anionic intermediate followed by elimination of nitrous acid. The high reactivity was maintained even when one of the nitro groups on the benzene moiety was replaced by a methyl group, which afforded corresponding cine-substituted products upon treatment with potassium cyanide

One-step synthesis of differently bis-functionalized isoxazoles by cycloaddition of carbamoylnitrile oxide with β-keto esters

A new protocol for synthesizing different functionalized isoxazoles is provided. Carbamoylnitrile oxide generated from nitroisoxazolone underwent inverse electron-demand 1,3-dipolar cycloaddition with 1,3-dicarbonyl compounds in the presence of magnesium acetate that formed magnesium enolatein situ. Although electron-deficient trifluoroacetoacetate did not undergo this cycloaddition under the same conditions, conversion to sodium enolate furnish the corresponding bis-functionalized trifluoromethylisoxazole. The DFT calculations using B3LYP 6-31G+(d,p) also supported the aforementioned reactivity

The Ring Transformation of 3-Methyl-5-nitropyrimidin-4(3H)-one

3-Methyl-5-nitropyrimidin-4(3H)-one readily reacts with carbonyl compounds to produce three kinds of ring transformations. The nitropyrimidinone behaves as the synthetic equivalent of activated diformylamine affording 3,5-difunctionalized 4-pyridones, 4,5-disubstituted pyrimidines and functionalized 4-aminopyridines. It also behaves like α-nitro-formylacetic acid to give 5,6-disubstituted 3-nitro-2-pyridones

Nitroisoxazolones Showing Diverse Chemical Behavior: A Use ful Building Block for Polyfunctionalized Systems

Background: 4-Functionalized isoxazolin-5-ones (isoxazolones) have attracted much attentions as precursors of functionalized building blocks because the multiple functionalities. These structural features facilitate the construction of large compound libraries that is important for development of new functional materials. However, the systematic review article dealing with nitroisoxazolone has not been published although they exhibit different reactivity from other functionalized isoxazolones. This review describes the interesting behavior of the nitroisoxazolone motif and its application to the synthesis of polyfunctionalized compounds. Methods: Peer-reviewed research literatures describing the chemistry of nitroisoxazolones were collected, and each paper was appraised using standard criteria. inclusion/exclusion criteria. The papers were analyzed, and divided according to the reaction patterns. Results: This review consists of two parts. In the former part, the chemistry of pyridinium salt of nitroisoxazolone is described, and in the latter part, chemistry of methylnitroisoxazolone is introduced. Sixty-eight papers were included in this review. Twelve papers deal with pyridinium salt or its ring-opened product, cyano-aci-nitroacetate. Nine papers mention the chemistry of methylnitroisoxazolones and derived nitroenamines and nitrile oxide. With regard to each chemistry, reaction mechanism and reactivity are discussed with citing related literatures. Conclusion: The findings of this review confirm the importance of nitroisoxazolones in synthetic chemistry for polyfunctionalized compounds, which are not readily available by alternative methods. This review will provide useful information and synthetic tools for many chemists studying synthetic chemistry and medicinal chemistry