A New Stereoselective Approach to the Substitution of Allyl Hydroxy Group in para -Mentha-1,2-diol in the Search for New Antiparkinsonian Agents.

Two approaches to the synthesis of para -menthene epoxide ((1 S ,5 S ,6 R ) - 4 ) are developed. The first approach includes a reaction between chlorohydrin 7 and NaH in THF. The second involves the formation of epoxide in the reaction of corresponding diacetate 6 with sodium tert -butoxide. One possible mechanism of this reaction is proposed to explain unexpected outcomes in the regio- and stereospecificity of epoxide (1 S ,5 S ,6 R ) - 4 formation. The epoxide ring in (1 S ,5 S ,6 R ) - 4 is then opened by various S - and O -nucleophiles. This series of reactions allows for the stereoselective synthesis of diverse derivatives of the monoterpenoid Prottremine 1 , a compound known for its antiparkinsonian activity, including promising antiparkinsonian properties.