C3-Thia and C3-carba isosteres of a carbocyclic influenza neuraminidase inhibitor, (3R,4R,5S)-4-acetamido-5-amino-3-propoxyl-1-cyclohexene-1-carboxylic acid

The importance of the oxygen atom in the C3 ether side chain of a carbocyclic influenza neuraminidase inhibitor 3 was investigated by replacement of the C3 ether oxygen atom of 3 with either a sulfur atom (compound 4) or a carbon atom (compound 5). The regio- and stereospecific syntheses of both isoteres are described starting from (−)-quinic acid.