Synthesis and reactivity of 4-silylated oxazoles

Synlett

Volumn , Issue 5, 2000, Pages 692-294

  Ducept, Pascal C ^a   Marsden, Stephen P ^a  

^a IMPERIAL COLLEGE LONDON   (United Kingdom)

Author keywords

Desilylation; Ipso substitution; Oxazoles; Silyl diazoacetate

Indexed keywords

OXAZOLE DERIVATIVE;

ARTICLE; CHEMICAL REACTION; CHEMICAL STRUCTURE; SYNTHESIS;

EID: 0034072954     PISSN: 09365214     EISSN: None     Source Type: Journal    
DOI: None     Document Type: Article

References (24)

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2. For a review of oxazole synthesis from diazocarbonyls and nitriles, see: Moody, C. J.; Doyle, K. J. Prog. Heterocyclic Chem. 1997, 9, 1.
3. Connell, R.; Scavo, F.; Helquist, P.; Åkermark, B. Tetrahedron Lett. 1986, 27, 5559.
4. Competing dimerisation of simple diazocarbonyls is problematic in reactions promoted by metal catalysts (Shankar, B. K. R.; Schechter, H. Tetrahedron Lett. 1982, 23, 2277) although successful examples of oxazole synthesis using aryldiazoketones have been reported: Moody, C. J.; Doyle, K. J. Synthesis 1994, 1021; Ibata, T.; Fukushima, K. Chem. Lett. 1992, 2197.
5. Competing dimerisation of simple diazocarbonyls is problematic in reactions promoted by metal catalysts (Shankar, B. K. R.; Schechter, H. Tetrahedron Lett. 1982, 23, 2277) although successful examples of oxazole synthesis using aryldiazoketones have been reported: Moody, C. J.; Doyle, K. J. Synthesis 1994, 1021; Ibata, T.; Fukushima, K. Chem. Lett. 1992, 2197.
6. Competing dimerisation of simple diazocarbonyls is problematic in reactions promoted by metal catalysts (Shankar, B. K. R.; Schechter, H. Tetrahedron Lett. 1982, 23, 2277) although successful examples of oxazole synthesis using aryldiazoketones have been reported: Moody, C. J.; Doyle, K. J. Synthesis 1994, 1021; Ibata, T.; Fukushima, K. Chem. Lett. 1992, 2197.
7. The use of formyl(carbomethoxyl)diazocarbonyls leads to 5-carbomethoxy-4-unsubstituted oxazoles: Connell, R.D.; Tebbe, M.; Helquist, P.; Åkermark, B. Tetrahedron Lett. 1991, 32, 17.
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11. (b) Marsden, S. P.; Pang, W.-K. Tetrahedron Lett. 1998, 39, 6077.
12. (c) Marsden, S. P.; Pang, W.-K. Chem. Commun. 1999, 1199.
13. Both vinyl and aryl silanes undergo ipso-electrophilic substitution; we believed that the reactivity of the 4-silylated oxazoles would parallel this chemistry. Colvin, E. Silicon in Organic Synthesis; Butterworths: London, 1981, pp 15-20.
14. Turchi, I. J.; Dewar, M. J. S. Chem. Rev. 1975, 75, 389.
15. Alt, M.; Maas, G. Tetrahedron 1994, 50, 7435.
16. 2Si, requires 304.1760.
17. The O-H insertion product was obtained as a 3:2 mixture of diastereoisomers in 51% yield. For a review of O-H insertion reactions of diazocarbonyl compounds, see: Miller, D. J.; Moody, C. J. Tetrahedron 1995, 51, 10811.
18. For example, only 8% of oxazole 3b is obtained when acetonitrile is used as both reagent and solvent. Nitriles are good ligands for the vacant coordination site in rhodium (II) carboxylates: (a) Drago, R. S.; Long, J. R.; Cosmano, R. Inorg. Chem. 1982, 21, 2196;
19. (b) Drago, R. S.; Tanner, S. P.; Richman, R. M.; Long, J. R. J. Am. Chem. Soc. 1979, 101, 2897.
20. Liotta, D.; Saindane, M.; Ott, W. Tetrahedron Lett. 1983, 24, 2473.
21. 2, requires 190.0868.
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23. 2 requires 315.9834.
24. For a previous example of a Sonogashira coupling to 4-bromooxazole, see: Sakamoto, T.; Nagata, H.; Kondo, Y.; Shiraiwa, M.; Yamanaka, H. Chem. Pharm. Bull. 1987, 35, 823.