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-derivativ es containing a carbamoyl function in 3-position and the trichloroethyliden e acetal group in 4,5-position. Additionally, an spiro-byproduct, 1R, 3R, 4 R, 5R)-3'-N-cyclohexyl-3-O-(cyclohexylcarbomyl)-4,5-O-(2,2,2-trichloroethyl idene) 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 co mpounds is possible by heating in methanolic sodium methoxide. (C) 1998 Els evier Science Ltd. All rights reserved.