ALIPHATIC SULFONATION .12. INTRAMOLECULAR COMPETITION IN FRIEDEL-CRAFTS SULFOCYCLIZATION OF OMEGA-(1-NAPHTHYL)-N-ALKENES AND 1,7-DIPHENYL-3-HEPTENE ON REACTION WITH SULFUR-TRIOXIDE

Reactions of the omega-(1-naphthyl)-n-alkenes 1a-9a and 1,7-diphenyl-3 -heptene (10) (substrates which allow intramolecular competition in an y occurring sulfocyclization) with sulfur trioxide were studied in the temperature range -60 to 25-degrees-C using dichloromethane as solven t and 1.5 mol equiv. of dioxane relative to the amount of SO3 as react ivity moderator. 4-(1-Naphthyl)-1-butene reacts with SO3, similar to a simple alkene, yielding at low temperature the beta-sultone 1b, which at 25-degrees-C in the presence of additional SO3 is converted into t he corresponding carbyl sulfate 1d. Reaction of the omega-(1-naphthyl) -n-alkenes 2a-5a, which have a -(CH2)2- linkage between the 1-naphthyl (1-Np) and C=C moieties, with 1.1 equiv. of SO3 at -60-degrees-C yiel ds very rapidly, quantitatively and stereospecifically the 1,2,3,4-tet rahydro-1-alkyl-phenanthrene-2-sulfonic acids 2f-5f. Reaction of the 3 -(1-naphthyl)-l-phenyl-1-propenes 8a and 9a, having a -CH2- linkage be tween the 1-Np and C=C moieties, with 1.1 mol equiv. of sulfur trioxid e at -60-degrees-C quantitatively yields the beta-sultones 8c and 9c, which upon increasing the temperature, are converted into trans-3-phen ylbenz[g]indane-2-sulfonic acid (11). Reaction of 1,7-diphenyl-3-hepte ne (10) with 1.1 equiv. of SO3 leads to exclusive formation of etrahyd ro-1-(3-phenylpropyl)naphthalene-2-sulfonic acid (13). Using ClSO3SiMe 3 instead of SO3, the reaction proceeds less selectively and yields, i n addition to 13, 18% of 4-tetrahydro-1-(3-phenyl-1-sulfopropyl)naphth alene (14). Mechanisms for the formation of the various products are s uggested and the observed selectivity in the sulfocyclizations are dis cussed.