| Popis: |
2,3:4,5-Di-O-cyclohexylidene-L-arabinose diethyl dithioacetal was treated with sodium methylsulfinylmethylide to prepare a novel compound, 4,5-cyclohexylidene-2-deoxy-L-erythro-pent-1-enose diethyl dithioacetal. The product undergoes a series of transformations in anhydrous ethanol in the presence of p-toluenesulfonic acid: alcoholysis of the cyclohexylidene protection, elimination of water, migration of the double bond, formation of an acyclic allyl cation, elimination of the ethylthio group, formation of a cyclic allyl cation, migration of the mercapto group from C1 to C3,addition of alcohol, and formation of an acetalized lactone. The latter was acetalized to obtain a diastereomeric mixture of 5-O-acetyl-2-deoxy-3-S-ethyl-L-threo- and -erythro-pentono-1,4-lactones. |
Full text from SpringerLink