Nojigiku alcohol

Tricyclene (8) has been oxidized in acetic acid/Et3N to the Nojigiku alcohol (9) in 11% yield (Eq. 8) [36]. The reaction was also conducted in a 2.25-kg scale to afford pure (9) in 65% yield from crude (8) containing alkenes. The olefins remained unconverted due to their higher oxidation potential. 

A tricyclene has been converted in acetic acid/Et3N to Nojigiku alcohol with a 77% yield by regioselective cleavage at the external cyclopropane C—C bond (Fig. 14) [88]. 

Electrooxidative ring opening of polycyclic terpenoids 25 has been investigated in an AcOH—EtjN—(C) system in an undivided cell. The electrolysis of tricyclene 25a at 15 °C yields exo-2,2-dimethyl-3-methylenebicyclo[2.2.1]heptan-5-ol 26a, Nojigiku alcohol, in 76% yield (Scheme 3-9)S6). The results reported on the electrooxidative cleavage of terpenoids are summarized in Table 3.2. 

A new synthesis of nojigiku alcohol (773) (Vol. 4, p. 554) starts from tricyclene (774) and we should perhaps recall the preparation of the latter from camphor (40) tosylhydrazone and sodium methoxide in decalin. [Tricyclene is also produced in other reactions leading to camphene (775), such as the reaction of 3-bromocamphor with methylaniline. ] TTie new synthesis consists in anodic oxidation with triethylamine in acetic acid, and yields 76% of 773, with 8% of the endo-isomer and 11% of diols. Oxidation of tricyclene (774) with lead tetraacetate also gives nojigiku alcohol (773), but as a minor (16%) product, the main product being camphor (40). Tricyclene having a plane of symmetry, these methods all lead to racemic 773. 

Bicyclo[2,2,l]heptanes.—Last year s Report incorrectly identifies vulgarole [Vol. 8, p. 49, line 21, formula (202 R = Ac) should be (208 R = Ac)]. A review of interest to this section concerns oxidation of bicyclic hydrocarbons using oxygen, hydroperoxides, peracids, and hydrogen peroxide. The full paper on nojigiku alcohol has appearedthe isolation of a new compound (132) has been referred to already. 

Tricyclene (37) has been oxidized—after careful optimization of the reaction conditions—in acetic acid/EtsN to the Nojigiku alcohol 38 in 77% yield, again with cleavage of a cyclopropane C—C bond (equation 24). The reaction was also conducted in a 2.25 kg scale to afford 38 from impure 37 mixed with alkenes. Due to the higher oxidation potentials of the alkenes, 38 was formed in 65% yield without conversion of the alkenes . 

The amount of the coupling product was found to be dependent upon the concentration of the dihalide in the metal-ammonia reductions, perhaps because of local high concentration effects. The oxidation of camphene by t-butyl perbenzoate in the presence of Cu salts affords, after saponification of the reaction mixture, nojigiku alcohol (458), among other products. ... 

Oxidation of camphene. When camphene (1) is allowed to react in acetonitrile at 80° with /-butyl perbenzoate and catalytic amounts of cuprous chloride and cupric benzoate, mainly alcohols are obtained after saponification (237o yield) rather than ethers (87o yield). The two principal alcohols are (2) and (3) the former is identical to nojigiku, isolated originally from a Japanese chrysanthemum. 

---