ALIPHATIC SULFONATION .9. REACTIONS OF OMEGA-PHENYLALKENES WITH SULFUR-TRIOXIDE - SULFONATION AND FRIEDEL-CRAFTS TYPE OF CYCLIZATION

Reactions of omega-phenylalkenes 1a-31a with sulfur trioxide were studied in the temperature range -60 to 25-degrees-C using dichloromethane as solvent and 1.5 mol equiv. of dioxane as reactivity moderator. Omega-phenylalkenes 1a-7a react just like simple alkenes: at low temperature, they yield the (thermally unstable) beta-sultones 1b-7b and 4c-7c, which at 25-degrees-C are converted into the corresponding carbyl sulfates. Reactions of omega-phenylalkenes 8a-10a, which have a -(CH2)3- linkage between the Ph and the C = C moieties, with 1.1 equiv. of SO3 at -60-degrees-C yield very rapidly and quantitatively the 1-(1-sulfoalkyl)-1,2,3,4-tetrahydronaphthalenes 8f and 9f ( = 10f). Reaction of omega-phenylalkenes 11a and 12a, having a -(CH2)2- linkage between Ph and C = C, with 1.1 mol equiv. of SO3 at -60-degrees-C leads to quantitative and stereospecific formation of 1-methyl-1,2,3,4-tetrahydronaphthalene-2-sulfonic acids 11h and 12h, respectively. The 5-(chlorophenyl)-2-pentenes 13a-16a clearly demonstrate the presence of beta-sultones 13b-16b and 13c-16c as the sole initial products leading to the Friedel-Crafts cyclization products 13h-16h. Reaction of 1,3-diphenyl-1-propenes 26a and 27a with 1.5 equiv. of SO3 at -60-degrees-C quantitatively yields beta-sultones 26c and 27c, which upon raising the temperature to -20-degrees-C, are slowly converted into trans-1-phenylindane-2-sulfonic acid (34). Attempted intermolecular Friedel-Crafts type of sulfoalkylation of arenes using beta-sultones as reagent failed. Reaction of, for example, trans-4,5-octanesultone with anisole instead led only to transfer sulfodeprotonation, to yield (E)-4-octene and 4-methoxybenzenesulfonic acid. Mechanisms for the formation of the various products are suggested.