Non-conventional epimerisation and functionalisation of quinic acid and shikimic acid methyl esters

In a convenient one-pot acetalation procedure using chloral/DCC, methyl (-)-quinate and methyl (-)-shikimate were converted into their 4-epi-derivatives containing a carbamoyl function in 3-position and the trichloroethylidene acetal group in 4,5-position. Additionally, an spiro-byproduct, 1R, 3R, 4R, 5R)-3′-N-cyclohexyl-3-O-(cyclohexylcarbomyl)-4,5-O-(2,2,2-trichloroethylidene)spiro[[cyclohexane-3,4,5-triol-1,5′-[1,3]oxazolidine]]-2′,4′-dione, was formed from methyl (-)-quinate in 10% yield. Decarbamoylation of the compounds is possible by heating in methanolic sodium methoxide.