Isocaryophyllene synthesis

Therefore, a rational synthesis of caryophyllenes should be designed in such a way that after proceeding through a series of common intermediates at a given step they may offer the opportunity to exert a stereochemical control in the formation of the endocyclic double bond. In this context, the synthesis reported by Corey as early as 1964 [1] is still more efficient than more recent syntheses in which only one isomer (isocaryophyllene, lb) is formed [2] or that require parallel synthetic sequences which start from compounds which are only remotely related to each other [3]. 

Similar observations were made in the dimethylketene adducts of partially resolved cyclonona-1,2-diene and cyclotrideca-1,2-diene (see Table 1). A total synthesis of isocaryophyllene was carried out using the dimethylketene adduct of the partially resolved allene 74 as an intermediate. However, in all of these cases the enantioselectivity of these processes was not determined since the optical purity of the products were not established. 

This cycloalkanone synthesis furnishes a short synthesis of isocaryophyllene (1), the (Z)-isomer of natural caryophyllene. In this example, the double bond isomerizes during the keto cyclization.2... 

An alternative synthesis of ( )-isocaryophylIene (253) has been achieved by the reaction sequence outlined in Scheme 27. ° The conversion of the bicyclic ketone (250) into isocaryophyllene (253) has previously been reported (cf. Vol. 5, p. 67) by another research group. ... 

A new synthesis of d/-isocaryophyllene has been used for the photochemical addition of 2-methylpropene to cis,cis-2,6-cyclononadienone as a method of generating the four-membered ring. ... 

In the area of natural product synthesis, the isomeric sesquiterpenes, caryo-phyllene, and isocaryophyllene have been studied with respect to monohydro-boration with dicyclohexylborane and the hydroboration of a butadiene telomer, 3-acetoxy-octa-l, 7-diene, is the first step in a study regarding the synthesis of d7-a-lipoic acid. The reaction of organoboranes with 2,5-dihy-droxy-l,4-benzoquinone with subsequent application to the synthesis of rapanone has been studied. ... 

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