Intramolecular competition in Friedel-Crafts sulfocyclization of ω-(1-naphthyl)-n-alkenes and 1,7-diphenyl-3-heptene on reaction with sulfur trioxide
✍ Scribed by Ruud M. Schonk; Imelda Lembeck; Bert H. Bakker; Hans Cerfontain
- Publisher
- Elsevier Science
- Year
- 2010
- Tongue
- English
- Weight
- 592 KB
- Volume
- 112
- Category
- Article
- ISSN
- 0165-0513
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
Reactions of the ω‐(1‐naphthyl)‐n‐alkenes 1a–9a and 1,7‐diphenyl‐3‐heptene (10) (substrates which allow intramolecular competition in any occurring sulfocyclization) with sulfur trioxide were studied in the temperature range −60 to 25°C using dichloromethane as solvent and 1.5 mol equiv. of dioxane relative to the amount of SO~3~ as reactivity moderator. 4‐(1‐Naphthyl)‐1‐butene reacts with SO~3~, similar to a simple alkene, yielding at low temperature the β‐sultone 1b, which at 25°C in the presence of additional SO~3~, is converted into the corresponding carbyl sulfate 1d. Reaction of the ω‐(1‐naphthyl)‐n‐alkenes 2a–5a, which have a ‐(CH~2~)~2~‐ linkage between the 1‐naphthyl (1‐Np) and C=C moieties, with 1.1 equiv. of SO~3~, at −60°C yields very rapidly, quantitatively and stereospecifically the 1,2,3,4‐tetrahydro‐1‐alkyl‐phenanthrene‐2‐sulfonic acids 2f–5f. Reaction of the 3‐(1‐naphthyl)‐1‐phenyl‐1‐propenes 8a and 9a, having a ‐CH~2~‐ linkage between the 1‐Np and C=C moieties, with 1.1 mol equiv. of sulfur trioxide at −60°C quantitatively yields the β‐sultones 8c and 9c, which upon increasing the temperature, are converted into trans‐3‐phenylbenz[g]indane‐2‐sulfonic acid (11). Reaction of 1,7‐diphenyl‐3‐heptene (10) with 1.1 equiv. of SO~3~, leads to exclusive formation of 1,2,3,4‐tetrahydro‐1‐(3‐phenylpropyl)naphthalene‐2‐sulfonic acid (13). Using ClSO~3~SiMe~3~, instead of SO~3~, the reaction proceeds less selectively and yields, in addition to 3. 18% of 1,2,3,4‐tetrahydro‐1‐(3‐phenyl‐1‐sulfopropyl)naphthalene (14). Mechanisms for the formation of the various products are suggested and the observed selectivity in the sulfocyclizations are discussed.