Tigaso oil, which is obtained as an
exudate from a tree of the Anacardiaceae family identified as Campnosperma sp.
vel. aff. C. brevipetiolata Volk., has been found to contain an optically
active compound. This is considered to be (+)-5-hydroxy-5-(nonadec- 10'-en-2'-onyl)cyclohex-2-enone
(V), a new type of natural product. It is very closely related to the phenol,
campnospermonol (I ; R=H) which is the major component of Tigaso oil, and is
readily converted into a mixture of campnospermonol and campnospermonyl alkyl
ether by heating in alcoholic hydrochloric acid. On pyrolysis, V yields
resorcinol and methyl oleyl ketone almost quantitatively.
($)-3-Hydroxy-3-(nonadecan-2'-ony1)cyclohexanone
(VI) obtained by catalytic hydrogenation of V is easily dehydrated to
3-(nonadecan-2'-onyl)cyclohex-2-enone (VII) which has acidic properties and
gives a yellow solution in alkali. Heating VII in alkali gives stearic acid and
3-methylcyclohex-2-enone as the principal products. When the hydroxydiketone
(VI) is heated the major reaction is dehydration to give VII, but pyrolysis
also takes place, giving methyl stearyl ketone and dihydroresorcinol.
3-(Nonadecan-2'-ony1)cyclohexanone (VIII) is obtained by catalytic
hydrogenation of VII and also by oxidation of the diol X, itself prepared from
hydrocampnospermonol (II ; R =H) by high pressure hydrogenation.
The structure originally assigned to
campnospermonol by Jones has been established by the synthesis of
hydrocampnospermonyl methyl ether, from 3-methoxyphenylacetyl chloride and
diheptadecyl cadmium.
The odour of Tigaso oil is partly due to a
small amount of a volatile ketone C7H12O which consists
mainly of 3-methylcyclohexanone ; probably a mixture of (+)- and (-)-isomers
with the (-)-isomer preponderant.
The Third Absorption Bands of Co-ordination Compounds. III. The Configuration of [Codg2NH3Cl]. A New Type of Optically Active Complex Radicals