The Role of Nonaromatic Isomers in the Photochemistry of 3,5-Dimethoxybenzyl Acetate

Journal of Organic Chemistry

Volumn 63, Issue 3, 1998, Pages 434-435

  Cozens, Frances L ^a   Pincock, Alexandra L ^a   Pincock, James A ^a   Smith, Richard ^a  

^a DALHOUSIE UNIVERSITY   (Canada)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 0001503025     PISSN: 00223263     EISSN: None     Source Type: Journal    
DOI: 10.1021/jo9722616     Document Type: Article

References (27)

1. Jaeger, D. A J. Am. Chem. Soc. 1974, 96, 6216-6217.
2. We thank Professor Jaeger for sending us his original laboratory notebooks, including spectra. This material was of invaluable help. Although we are reinterpreting his observations, the quality of his experiments and the clarity of the notebooks would serve as models for anyone. Without the visual incentive of his spectra, we would have had even more difficulty completing these experiments.
3. Pincock, J. A.; Wedge, P. J. J. Org. Chem. 1994, 59, 5587-5595.
4. Pincock, J. A. Acc. Chem. Res 1997, 30, 43-49.
5. Zimmerman, H. E. J. Am. Chem. Soc., 1995, 777, 8988-8991.
6. Zimmerman, H. E.; Sandel, V. R. J. Am. Chem. Soc. 1963, 85, 915-922.
7. Pirrung, M. C.; Bradley, J.-C. J. Org. Chem. 1995, 60, 1116-1117.
8. Cameron, J. F.; Wilson, C. G.; Frechet, J. M. J. J. Am. Chem. Soc. 1996, 118, 12925-12937.
9. Vycor-filtered, 450 W, medium-pressure Hanovia mercury lamp.
10. Greater than 90% conversion of 400 mg of 1 in 280 mL of hexanes after 30 min as determined by HPLC on silica gel with 5% ethyl acetate in hexanes as eluant.
11. Silica gel dry-flash chromatography using 5% ethyl acetate in hexanes as eluant gave fractions with purity as high as 90% but always contaminated with DMBA.
12. Kopecky, K. R.; Lau, M.-P. J. Org. Chem. 1978, 43, 525-526.
13. Hasselmann, D.; Loosen, K. Angew. Chem., Int. Ed. Engl. 1978, 77, 606-608.
14. Silverstein, R. M.; Bassler, G. C.; Morrill, T. C. Spectrometric Identification of Organic Compounds, 5th ed.; John Wiley & Sons: New York, 1991; p 213.
15. 1H correlated spectra.
16. Although we have no evidence to support the assignment, the acetate functional group is assumed to be in the more stable exo position.
17. 8). Second, in our attempts to isolate the photoisomer, we monitored chromatography fractions by HPLC with UV detection at 320 nm. Those fractions that contained 5, when first obtained, were transparent but, after standing overnight at room temperature, were strongly absorbant. Both of these observations result from increasing amounts of 2 contaminating 5 with time.
18. 13
19. 13C correlated spectra.
20. 1 reported the same process in benzene at 50°C, and this observation was used as support for the assignment of the structure 2 to the photoisomer isolated. In fact, the process observed was thermal conversion of 5 to 2 to 6.
21. Continuum NY-61 Nd:YAG laser at 266 nm, ≤15 mJ/pulse, ≤8 ns/ pulse.
22. † = -14 eu and in other solvents (ethanol, 2-propanol) at 25°C gave a linear mY correlation with Y = 0.57.
23. (a) Jiminez, M. C.; Miranda, M. A.; Scaiano,. C.; Tormos, R. Chem. Commun. 1997, 1487-1488.
24. (b) Mirand, M. A. In Handbook of Organic Photochemistry and Photobiology; Horspool, W. M., Song, P. S., Eds.; CRC Press: Boca Raton, 1995; pp 570-578.
25. We have not been able to isolate this compound because it is contained in chromatograpy fractions that are mixtures of hydrocarbons dominated by the aromatic isomer, 3,5-dimethoxyethylbenzene.
26. Hilborn, J. W.; Pincock, J. A. J. Am. Chem. Soc. 1991, 113, 2683-2686.
27. a = 5.03), and therefore, acetate is the better leaving group.