Methyl piperitol

Mixed arylation of bifunctional substrates, such as those containing two /3-ketoester groups in their structure can be made. This possibility was used to synthesize unsymmetrically substituted compounds containing two different aryl groups (Scheme 2). One-pot treatment of the dibenzyl 3,7-dioxobicyclo [3.3.0]-octane-2,6-dicarboxylate 6 with a mixture of two aryllead triacetates 7 and 8 afforded a mixture of the unsymmetrical diaryl derivative 10 with the two symmetrical diaryl compounds 9 and 11. When the arylation was performed with 1.1 equiv. of each aryllead reagents 7 and 8, a mixture of 9-11 in a ratio 0.46 1 0.72 was obtained. This ratio became 0.43 1 0.49, when 0.86 equiv. of 7 and 1.33 equiv. of 8 were used. This compound 10, isolated in a 33% yield, was eventually elaborated to complete a total synthesis of ( ) methyl piperitol.25... 

Cp2TiCl-mediated 5-exo-trig cyclizations have been intensively exploited by Roy et al. for the total synthesis of ( )-dihydroprotolichesterinic and ( )-roccellaric acids, ( )-sesamin, ( )-dihydrosesamin, ( )-acuminatin, ( )-eudesmin, ( )-lariciresinol, ( )-pinoresinol, ( )-piperitol, ( )-acumi-natin methyl ether, (zh)-sanshodiol methyl ether, ( )-piperitol methyl ether, ( )-pinoresinol monomethyl ether, ( )-lariciresinol monomethyl ether, and ( )-lariciresinol dimethyl ether [ 100-103]. Moreover, this group has very recently reported the enantioselective synthesis of (-)-sesamin (Scheme 19), (-)-dihydrosesamin, (-)-acuminatin, and (-)-methyl piperitol by radical cyclization of chiral epoxides initiated by Cp2TiCl [104]. 

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