Camphene-1-carboxylic acid

Starting with camphene-1-carboxylic acid (29), isolongifolene has been synthesized (34) along the lines depicted in Chart 5. The crucial step... 

X-Ray diffraction studies of ( )-carbocamphenilone," of (-)-camphene-8-carboxylic acid," and of a number of Money s brominated camphor derivatives (Vol. 6, p. 39 Vol. 7, p. 40) have been published they include 8-bromo-camphor," l,7-dibromo-3,3,4-trimethylnorbornan-2-one, l,7-dibromo-4-... 

Related to the previous example is the report that the AA of carboxylic acids [24] - as well as of carboxylic amides [25] or pinenes and camphenes [26] - proceeds well in the absence of any ligand. It can be assumed that the reaction is autocatalytic, however, no definite experimental evidence has been provided to prove this speculation. 

The esterification of camphene (2) with acetic acid at a reaction temperature of 80 °C showed a conversion of 88% with a selectivity of 87% with the catalyst SAC 13 and a selectivity of 88% with the Amberlyst A 15. The carboxylic acid was in four-fold molar excess with 10 wt% catalyst. Both, the SAC 13 and the A 15 show high activity (each 88% conversion) and high selectivity in this reaction. This olefinic compound seems to be so reactive as to render high conversion independently of the acid strength of the catalyst. This could be due to the terminal double bond and to the very stable carbocation formed by protonation. 

Camphene has been hydroformylated under varying conditions (Scheme 6.12). In the first studies, it was treated at a syngas pressure of 3000 psi (about 207 bar) in the presence of an unmodified Co catalyst [82]. The protocol was conducted in a 60 g scale and gave 65% of the diastereomeric aldehydes that showed a note of borneol and camphor. The position of the carbonyl group was clarified chemically by conversion into the corresponding carboxylic acid, ester, hydroxy, or bromo derivatives. 

CiiH,s02, (-)-Camphene-8-carboxylic acid, 43B, 687 44B, 494 C13H21NOS, (lR,3S,4R)-N,N-Dimethyl-3-camphorcarbothioamide, 46B, 177 C,3H24BrN, 3-N-Dimethylaminomethylpinene-2(10) hydrobromide, 37B,... 

This reaction was first reported by Riemschneider in 1949. It is an acidic transformation of alkyl or aryl thiocyanates into thiocarbamates and is known as the Riemschneider reaction. In this reaction, when thiocyanates are treated with concentrated sulfuric acid, the corresponding thiocarbamates are obtained. In parallel, when thiocyanates are treated with concentrated sulfuric acid in the presence of alcohol or olefin, the corresponding A -substituted carbamates are yielded. The alcohols or olefins that are stable in the presence of sulfuric acid, including isopropyl alcohol, cc-butyl alcohol, r-butyl alcohol, cyclohex-anol, isobutylene, and camphene aU are suitable for this reaction, whereas low-order alcohols such as methanol and ethanol do not react with thiocyanate to give the corresponding A -substituted thiocarbamates. hi addition, the benzyl thiocyante and some ortho-substituted phenyl thiocyanates cannot be transformed into the corresponding thiocarbamates under these conditions because they are sensitive to sulfuric acid. Some unsuitable thiocyanates are o-carboxyl, o-methoxy, o-nitrophenyl thiocyanates, and o-methyM-amino phenyl thiocyanate. ... 

---