Chemistry

V. V. Perekalin and A. S. Polyanskaya

Interaction of Nitroolefins and Compounds with Active Methyl Groups

(Presented by Academician I. N. Nazarov, 24 XI 1956)

Earlier, one of us showed that nitroolefins (nitrostyrene), in the presence of basic catalysts, readily condense with substances containing labile hydrogen atoms in methylene groups (malonic and acetoacetic esters, acetyl- and benzoylacetone) (¹–³).

It seemed of interest to extend this reaction to compounds with labile hydrogen atoms in methyl groups. The interaction of these substances with cationoid reagents—aldehydes, nitroso and diazo compounds—has long been well studied, whereas reactions with nitroolefins have been described only very sparsely (⁴,⁵).

We have for the first time carried out the interaction of nitroolefins of the aliphatic, aromatic, and heterocyclic series (nitroisohexylene, nitrostyrene, and furyl-nitroethylene) with active methyl components: trinitrotoluene, mesomethylacridine, and the iodomethylates of quinaldine and methylbenzthiazole.

The synthesis proceeded on heating equimolecular quantities of the substances in organic solvents in the presence of basic catalysts; the best yields were usually obtained in the presence of triethylamine. In some cases the reaction occurred instantaneously upon addition of traces of catalyst to the melt of the components (condensation of nitrostyrene with trinitrotoluene, yield 70%). The reaction conditions and the analytical results for the synthesized substances are given in Tables 1–2.

On reduction and heating with hydrochloric acid, the condensation products were converted into the corresponding amines and carboxylic acids.

It may be assumed that the reaction mechanism consists in the formation of a reaction complex, which is converted into the final product as a result of addition of the methyl component at positions 1–4 of the nitroolefin. The methyl group of the methyl component is active owing to conjugation with electrophilic groups ($\pi$-, $\sigma$-conjugation), while the reactivity of the nitroolefin is increased by fixation of its electron deficiency by the catalyst.

[
\begin{aligned}
& (C_2H_5)_3N \cdots
\begin{matrix}
& R_1\[-2pt]
& |\[-2pt]
& CH_2
\end{matrix}
\overset{+\delta}{\cdots}
CHR
\begin{matrix}
H\[-2pt]
\cdots\[-2pt]
O^{-\delta}
\end{matrix}
\begin{matrix}
\[-2pt]
|\[-2pt]
CH\[-2pt]
\backslash N\[-2pt]
|\[-2pt]
O
\end{matrix}
\;\longrightarrow\;
R{-}CH
\begin{matrix}
R_1\[-2pt]
|\[-2pt]
CH_2
\end{matrix}
\begin{matrix}
\[-2pt]
|\[-2pt]
CH\;\;OH\[-2pt]
\backslash N\[-2pt]
|\[-2pt]
O
\end{matrix}
\;\longrightarrow\;
R_1{-}CH_2{-}CH{-}CH_2{-}NO_2\
&\hspace{37em} |\[-2pt]
&\hspace{37em} R
\end{aligned}
]

where $R$ is alkyl, aryl, or heterocycle; $R_1$ is an electrophilic residue conjugated with the methyl group.

Table 1

Table 1 (continued)

* tea — triethylamine.

Note. (R_1 — CH_2 — CH — (CH_3)_2;\quad R_2 — C_6H_5;\quad R_3 —) furyl.

Table 2

The reaction described is general in character and opens a route for introducing a nitroethyl group, linked to various alkyl, aryl, and heterocyclic residues, into compounds with active methyl groups. In the simplest case (in the interaction of active methyl components with a nitroethylene), this reaction may be characterized as a nitroethylation reaction.

Received
22 III 1956

REFERENCES CITED

1. V. V. Perekalin, A. S. Sopova, ZhOKh, 24, 513 (1954).
2. V. V. Perekalin, A. S. Sopova, DAN, 95, 993 (1954).
3. V. V. Perekalin, A. S. Sopova, Uspekhi khimii, 24, 613 (1955).
4. H. B. Hass, E. F. Riley, Chem. Rev., 32, 414 (1946).
5. A. Lambert, H. Piggott, J. Chem. Soc., 1947, 1948.