Reactions of ω-phenylalkenes with sulfur trioxide; sulfonation and Friedel-Crafts type of cyclization

✍ Scribed by Ruud M. Schonk; Bert H. Bakker; Hans Cerfontain

• Publisher: Elsevier Science
• Year: 2010
• Tongue: English
• Weight: 1018 KB
• Volume: 111
• Category: Article
• ISSN: 0165-0513
• DOI: 10.1002/recl.19921110903

✦ Synopsis

Abstract

Reactions of ω‐phenylalkenes 1a‐31a with sulfur trioxide were studied in the temperature range −60 to 25°C using dichloromethane as solvent and 1.5 mol equiv. of dioxane as reactivity moderator. ω‐Phenylalkenes 1a‐7a react just like simple alkenes: at low temperature, they yield the (thermally unstable) β‐sultones 1b‐7b and 4c‐7c, which at 25°C are converted into the corresponding carbyl sulfates. Reactions of ω‐phenylalkenes 8a‐10a, which have a ‐(CH~2~)~3~‐ linkage between the Ph and the C = C moieties, with 1.1 equiv. of SO~3~ at −60°C yield very rapidly and quantitatively the 1‐(1‐sulfoalkyl)‐1,2,3,4‐tetrahydronaphthalenes 8f and 9f (= 10f). Reaction of ω‐phenylalkenes 11a and 12a, having a ‐(CH~2~)~2~‐ linkage between Ph and C = C, with 1.1 mol equiv. of SO~3~ at − 60°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 β‐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 SO~3~ at − 60°C quantitatively yields β‐sultones 26c and 27c, which upon raising the temperature to − 20°C, are slowly converted into trans‐1‐phenylindane‐2‐sulfonic acid (34).

Attempted intermolecular Friedel‐Crafts type of sulfoalkylation of arenes using β‐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.