|Subject||1 thia alpha tocopherol; 2,2,5,7,8 pentamethylthiochroman 6 ol; 2,5,7,8 tetramethylthiochroman 6 ol; 5,7,8 trimethylthiochroman 6 ol; drug analysis; drug identification; drug synthesis; gas chromatography; mass spectrometry; nuclear magnetic resonance; theoretical study; thin layer chromatography|
The syntheses of 5,7,8-trimethyl-, 2,5,7,8-tetramethyl-, and 2,2,5,7,8-pentamethyl-6-hydroxythiochromans have been achieved by a Michael-type condensation of methyl acrylate and related methyl esters with 2,3,5-trimethyl-4-hydroxythiochromans followed by cyclization of the free acid and reduction. These three previously unknown compounds can serve as simple models for the still unknown 1-thia-α-tocopherol (1), which could not be prepared by this route. Indeed, two purported syntheses of 18,9 have been shown to yield an essentially identical mixture of five isomers of the desired compound. For three components in this mixture, including the two major products, it is highly probable that the initial condensation at sulfur has not been followed by ring closure.