Oxidative Cleavage of the Double Bonds of Styrenes with a Combination of Mesoporous Silica FSM-16 and I₂ under Photoirradiation

Abstract

A mesoporous silica FSM-16 was found to be a recyclable promoter for the oxidative cleavage of double bonds, which are conjugated with an aromatic nucleus, to afford the corresponding carboxylic acid in the presence of catalytic iodine under photoirradiation conditions.

Key words

oxidative cleavage - mesoporous silica - FSM-16 - iodine - photochemistry

References

• 1 Comprehensive Organic Transformations: A Guide to Functional Group Preparations   Larock RC. Wiley-VCH; New York: 1989. 
• 2 Hudlicky M. Oxidations in Organic Chemistry, ACS Monograph 186   American Chemical Society; Washington, DC: 1990.  p.77-84  
• 3a Inagaki S. Koiwai A. Suzuki N. Fukushima Y. Kuroda K. Bull. Chem. Soc. Jpn.  1996,  69:  1449 
• 3b Inagaki S. Fukushima Y. Kuroda KJ. Chem. Soc., Chem. Commun.  1993,  680 
• 4a Itoh A. Kodama T. Inagaki S. Masaki Y. Org. Lett.  2000,  2:  331 
• 4b Itoh A. Kodama T. Inagaki S. Masaki Y. Chem. Lett.  2000,  542 
• 4c Itoh A. Kodama T. Inagaki S. Masaki Y. Org. Lett.  2000,  2:  2455 
• 4d Itoh A. Kodama T. Masaki Y. Chem. Lett.  2001,  686 
• 4e Itoh A. Kodama T. Inagaki S. Masaki Y. Org. Lett.  2001,  3:  2653 
• 6 The reaction will be completed in a much shorter reaction time than that indicated in the table with a new 400-W high-pressure mercury lamp, since the lamp, we used, is thought to be deteriorated: it had been used for a long time (14000 hrs) before this study. Product 2, for example, was afforded in 80% yield for 18 h reaction with a new lamp when 1 was used as starting material.
• 8 Kresge CT. Leonowicz ME. Roth WJ. Vartuli JC. Beck JS. Nature  1992,  359:  710 
• 9 Tanev PT. Pinnavaia TJ. Science  1995,  267:  865 
• 10a Zhang W. Froba M. Wang J. Tanev PT. Wong J. Pinnavaia TJ. J. Am. Chem. Soc.  1996,  118:  9164 
• 10b Tanev PT. Chibwe M. Pinnavaia TJ. Nature  1994,  368:  321 
• 11 The pore walls of FSM-16 with higher stability than MCM-41 will suppress the conversion of strained siloxane bridges, which are proposed to be the active sites for photo reaction, into inactive unstrained bridges, see: Inaki Y. Yoshida H. Kimura K. Inagaki S. Fukushima Y. Hattori T. Phys. Chem. Chem. Phys.  2000,  2:  5293 

5

A typical procedure follows: In a pyrex tube, a suspension of 4-tert-butylstyrene (1, 50 mg), iodine and silica (100 mg) in dry i-Pr₂O (5 mL) was stirred, and irradiated externally at room temperature with a 400-W high-pressure mercury lamp under aerobic atmosphere for 36 h. FSM-16 was then filtered off and washed with ethyl acetate, and the filtrate was washed with aq. sodium thiosulfate solution and brine. The organic layer was dried over magnesium sulfate and concentrated under reduced pressure. Pure 4-tert-butylbenzoic acid (2) (46 mg, 82%) was obtained after purification by preparative TLC.

7

The unit cell dimension of FSM-16 was 45.3 nm. The pore diameter was 2.8 nm, and the specific surface area was 948 m²/g.