HOMOCHIRAL FLUOROORGANIC COMPOUNDS .17. 2-(PARA-TOLYLSULPHINYLMETHYL)-3-FLUOROTETRAHYDROPYRANS AND 2-(PARA-TOLYLSULPHINYLMETHYL)-3-FLUOROTETRAHYDROFURANS THROUGH INTRAMOLECULAR OXYMERCURIATION

The four unsaturated alpha-fluoro alcohols, 3-fluoro-1-[(p-tolyl)sulphinyl]hept-5-en-2-ols and 3-fluoro-6-methyl-1-[(p-tolyl)sulphinyl]hept-5-en-2-ols 3 having the (2S,3S,R(s)) or (2S,3R,R(s)) absolute configuration, gave the corresponding 6-methyl- or 6,6-dimethyl-substituted 5-chloromercurio-3-fluoro-2-[(p-tolyl)sulphinyl]tetrahydropyrans 5 and 6 and the 5-[1'-(chloromercurio)ethyl]-3-fluoro-2-[(p-tolyl)sulphinyl]tetrahydrofurans 4 by 'endo' or 'exo' cyclooxymercuriation promoted by mercury(II) trifluoroacetate. All the synthesized compounds have been isolated in optically pure form and their structure, absolute configuration, and preferred conformation have been established by H-1, C-13 and F-19 NMR studies. Elaboration of the chloromercurio and sulphinylmethyl substituents on a couple of diastereoisomeric tetrahydropyrans 6 allowed us to obtain the corresponding 3-fluoro-2-hydroxymethyltetrahydropyrans 11.