Chemistry

Academician B. A. ARBUZOV and V. A. FRINOVSKAYA

OXIDES OF SOME DERIVATIVES OF α-PINENE AND THEIR ISOMERIZATION

In a series of previous works it was established that the oxide of α-pinene and of other bicyclic terpenes undergoes complex transformations under the influence of various reagents. Thus, under the influence of zinc bromide and certain other catalysts, α-pinene oxide is converted into the isomeric campholenic aldehyde. Such isomerization is accompanied by a profound rearrangement of the original skeleton of α-pinene oxide ((^{1-2})). It had been found still earlier ((^3)) that cyclohexene oxide is readily isomerized into cyclopentane aldehyde.

In the work of B. A. Arbuzov, Z. G. Isaeva, and E. G. Kataev ((^4)) it was shown that the introduction of certain substituents into the nucleus of cyclohexene oxide increases the stability of the oxide to such an extent that it was not possible to isomerize the indicated derivatives. From this point of view, it seemed of interest to obtain oxides of various derivatives of α-pinene and to study their capacity for isomerization.

We synthesized—by oxidation with acetyl hydroperoxide of the corresponding derivatives of α-pinene—oxides containing the myrtenyl radical, and carried out their isomerization reactions under the influence of zinc chloride:

[
\begin{aligned}
&\text{(myrtenyl derivative with } \mathrm{CH_2X}\text{)}
\;+\; \mathrm{CH_3COOOH}
\;\longrightarrow\;
\text{(corresponding oxide)}
\;\xrightarrow{\mathrm{ZnBr_2}}\;
\text{(aldehyde with } \mathrm{CHO}\text{)}
\end{aligned}
]

where (X = \mathrm{OCH_3},\ \mathrm{OC_3H_7})-iso, (\mathrm{OC_4H_9},\ \mathrm{OC_4H_9})-iso, (\mathrm{Cl},\ \mathrm{OCOCH_3},\ \mathrm{C_2H_5},\ \mathrm{C_3H_7})-iso, (\mathrm{OH}).

Derivatives of α-pinene were obtained from myrtenyl chloride by the action of the corresponding reagents. The constants of derivatives not described in the literature—

Table 1

Note.

[
\begin{aligned}
\mathrm{I}:&\quad \text{myrtenyl } \mathrm{CH_2OCH(CH_3)_2}\ \text{derivative},\
\mathrm{II}:&\quad \text{myrtenyl } \mathrm{CH_2OCH_2CH(CH_3)_2}\ \text{derivative},\
\mathrm{III}:&\quad \text{myrtenyl } \mathrm{CH_2OC_4H_9}\ \text{derivative}.
\end{aligned}
]

Table 2

Note.

I: α-pinene oxide derivative with —CH₂CH₂CH₃ substituent.
II: α-pinene oxide derivative with —CH₂CH(CH₃)₂ substituent.
III: α-pinene oxide derivative with —CH₂Cl substituent.
IV: α-pinene oxide derivative with —CH₂OH substituent.
V: α-pinene oxide derivative with —CH₂OC(O)CH₃ substituent.
VI: α-pinene oxide derivative with —CH₂OCH₃ substituent.
VII: α-pinene oxide derivative with —CH₂OCH(CH₃)₂ substituent.
VIII: α-pinene oxide derivative with —CH₂OC₄H₉ substituent.
IX: α-pinene oxide derivative with —CH₂OCH₂CH(CH₃)₂ substituent.

Table 3

Note.

I: campholenic aldehyde derivative with —CH₂CH(CH₃)₂ and —CHO substituents.
II: campholenic aldehyde derivative with —CH₂OCH₃ and —CHO substituents.
III: campholenic aldehyde derivative with —CH₂OC(O)CH₃ and —CHO substituents.
IV: campholenic aldehyde derivative with —CH₂Cl and —CHO substituents.

…are given in Table 1. The properties of the oxides obtained by us that have not been described in the literature are given in Table 2. Some of the oxides obtained were subjected to the isomerization reaction. The isomerization of the oxides obtained was carried out in the presence of zinc chloride as catalyst. As a result, the corresponding derivatives of campholenic aldehyde were isolated. The properties of the obtained derivatives of campholenic aldehyde are presented in Table 3.

The structure of the obtained derivatives of campholenic aldehyde was proved by their physical properties ($MR_D$), by determination of the presence of a double bond, and by oxidation with silver oxide to the corresponding substituted campholenic acid. The substituted campholenic acids were analyzed in the form of their silver salts.

As can be seen from the data presented, the isomerization of the studied derivatives of $\alpha$-pinene oxide proceeds analogously to the isomerization of $\alpha$-pinene oxide and leads to the formation of substituted campholenic aldehyde. The isomerization proceeds less smoothly, and the yield of the corresponding substituted derivatives of campholenic aldehyde is 25–30%.

Scientific Research Chemical Institute
named after A. M. Butlerov
at Kazan State University
named after V. I. Ulyanov-Lenin

Received
13 X 1956

REFERENCES

1. B. A. Arbuzov, Studies in the Field of Isomeric Transformations of Bicyclic Terpenes, dissertation, Kazan, 1936, p. 149.
2. B. A. Arbuzov, Z. G. Isaeva, ZhOKh, 19, 884 (1949).
3. P. Bedos, C. R., 189, 255 (1929).
4. B. A. Arbuzov, Z. G. Isaeva, E. G. Kataev, Scientific Notes of Kazan State University, vol. I (1950).