Camphenic acid synthesis

The conversion of ( )-camphor into the substituted camphene (168) by BF3,Et20-catalysed addition of ethyl diazoacetate should prove useful in sesquiterpenoid synthesis the isomeric camphene (169) is also obtained, but is converted quantitatively into (168) on treatment with zinc-acetic acid.262 The luminescence spectra of... 

An alternative route for the synthesis of primary phosphines involves the disproportionation of phosphinic acids, RP(0)(0H)H, at elevated temperatures. This procedure has been used in the synthesis of endo-8-camphanylphosphine (29) from inexpensive camphene by pyrolysis at 220-240 °C (Equation (8)).38 The phosphine is a colorless, low-melting-point solid that partly crystallizes on standing or, in other preparations, is obtained as an air-sensitive, odorous liquid. 

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. 

Bifimctional catalytic composites consisting in poly(vinyl alcohol) crosslinked with sulfosuccinic acid and Co(acac)2 complex or Co(acac)2trien encaged in NaY zeolite dispersed in the polymeric matrix, are active catalysts for the hydration of camphene and oxidation of isobomeol, making possible the one pot synthesis of camphor from camphene. The way as the Co complex is immobilised in the polymer matrix, directly or entrapped in zeolite Y, leads to opposite effects in the catalytic activity, probably due to the competition between transport and sorption phenomena. 

The acid catalysed isomerization of a-pinene proceeds via two types of reactions, one giving bi- and tricyclic products such as camphene, p-pinene, tricyclene, and bornylene and the other giving rise to monocyclic compounds such as dipentene, terpinolene, a-terpinene, y-terpinene and p-cymene [1]. Over solid catalysts such as clays, mineral oxides and inorganic salts,the main product is camphene [2], of particular interest as an intermediate in the synthesis of camphor. Camphor is of value due to its aroma and pharmaceutical properties. 

Camphor had been prepared from camphoric acid by Haller. Komppa synthesised camphoric acid from dimethylglutaric ester and from it obtained camphor. Perkin and J. F. Thorpe independently synthesised camphoric acid. When Komppa (1909) published the details of his synthesis, Thorpe and G. L. Blanc doubted its validity, but later confirmed that Komppa was correct. The formation of camphene from bornyl chloride involves what is called a Wagner-Meerwein rearrangement. ... 

Acid-catalyzed isomerization of a-pinene gives a mixture of camphene (27) and tricy-clene [508-32-7] (115). The process is carried out by heating with Ti02 catalysts or other activated clays and the products are obtained in a 4 1 equilibrium mixture in about an 80% yield. Tricyclene undergoes reactions identical to those of camphene therefore, the crude material is often used as such for further synthesis. 

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