Sonogashira coupling of functionalized trifloyl oxazoles and thiazoles with terminal alkynes: Synthesis of disubstituted heterocycles

Organic Letters

Volumn 4, Issue 15, 2002, Pages 2485-2488

  Langille, Neil F ^a   Dakin, Les A ^a   Panek, James S ^a  

^a BOSTON UNIVERSITY   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

ALKYNE; HETEROCYCLIC COMPOUND; OXAZOLE DERIVATIVE; PALLADIUM; THIAZOLE DERIVATIVE;

ARTICLE; CATALYSIS; CHEMISTRY; METHODOLOGY; SYNTHESIS;

ALKYNES; CATALYSIS; CHEMISTRY, PHARMACEUTICAL; HETEROCYCLIC COMPOUNDS; OXAZOLES; PALLADIUM; THIAZOLES;

EID: 0001544736     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol026099r     Document Type: Article

References (20)

1. For methods of triflate preparation, see: (a) Stang, P. J.; Hanack, M.; Subramanian, L. R. Synthesis 1982, 85-126.
2. (b) McMurry, J. E.; Scott, W. J. Tetrahedron Lett. 1983, 24, 979-982.
3. For a review of triflate chemistry, see: (a) Ritter, K. Synthesis 1993, 735-762.
4. For aryl triflates in Sonogashira reactions, see: (b) Chen, Q.-Y.; Yang, Z.-Y. Tetrahedron Lett. 1986, 27, 1171-1174.
5. All heterocycles utilized in this letter are synthesized through existing protocols. Experimental details for the synthesis of each heterocycle and references for all methods used are provided in Supporting Information.
6. (a) Kelly, T. R.; Lang, F. J. Org. Chem. 1996, 61, 4623-4633.
7. (b) Barrett, A. G. M.; Khort, J. T. Synlett 1995, 415-416.
8. (a) Schaus, J. V.; Panek, J. S. Org. Lett. 2000, 2, 469-471.
9. For an application of this methodology in the total synthesis of phorboxazole A, see: (b) Smith, A. B., III; Verhoest, P. R.; Minbiole, K. P.; Schelhaas, M. J. Am. Chem. Soc. 2001, 123, 4834-4836.
10. (c) Smith, A. B., III; Minbiole, K. P.; Verhoest, P. R.; Schelhaas, M. J. Am. Chem. Soc. 2001, 123, 10942-10953.
11. (a) Campbell, I. B. In Organocopper Reagents. A Practical Approach; Taylor, R. J. K., Ed.; Oxford University Press: Oxford, 1994; Chapter 10, pp 217-236.
12. (b) Sonogashira, K. In Comprehensive Organic Synthesis; Trost, B. M., Fleming, I., Eds.; Pergamon: Oxford, 1991; Volume 3, pp 521-548.
13. For a mechanistic rationale, see: Liu, Q.; Burton, D. J. Tetrahedron Lett. 1997, 38, 4371-4374.
14. (a) Wellmar, U.; Hörnfeldt, A.-B.; Gronowitz, S. J. Heterocycl. Chem. 1995, 32, 1159-1163.
15. (b) Bach, T.; Heuser, S. Tetrahedron Lett. 2000, 41, 1707-1710.
16. Bach, T.; Heuser, S. Angew. Chem., Int. Ed. 2001, 40, 3184-3185.
17. 3N control experiments produced no thiazolone. For this less reactive 2-triflate, method A provided clean coupling without decomposition.
18. 3N, while 2,6-di-tert-butylpyridine resulted in no reaction.
19. 3N and elevated temperature are required to achieve a Sonogashira coupling at the 4-position (see 6d, 6e).
20. Dakin, L. A.; Langille, N. F.; Panek, J. S. Submitted for publication.