Enantiospecific synthesis of a chrysanthemic acid precursor by the Katsuki-Sharpless epoxidation and the stork cyclisation

Article abstract of DOI:10.1016/S0040-4039(00)78805-8

The 1,4 addition of the anion of allylphenylthioether to 3,3-dimethylacrylonitrile occurred in 76% at the α position to the sulfur. The allylic alcohol 5 obtained from thioether 3 was asymetrically epoxidised with the Katsuki-Sharpless procedure to [4S,5R] epoxyalcohol 6 (ee> 94%). The silyl ether 8 was cyclised to the cis and trans nitrile 9. Cleavage of the glycol 10 gave the cis 11 and trans-aldehyde 12. Later 12 was converted to [1R,3R] trans chrysanthemic nitrile 13 (ee 92%).