Benzofurans prepared by C-H bond functionalization with acylsilanes

Angewandte Chemie - International Edition

Volumn 48, Issue 4, 2009, Pages 784-786

  Shen, Zengming ^a   Dong, Vy M ^a  

^a UNIVERSITY OF TORONTO   (Canada)

Author keywords

Acylsilanes; Brook rearrangement; C H insertion; Carbenes

Indexed keywords

ACYLSILANES; BENZOFURAN; BENZOFURANS; BROOK REARRANGEMENT; C-H INSERTION; CARBENES; CHEMICAL EQUATIONS; H BONDS; SILOXYCARBENE; TANDEM REACTIONS;

CHEMICAL REACTIONS;

EID: 58249121811     PISSN: 14337851     EISSN: None     Source Type: Journal    
DOI: 10.1002/anie.200804854     Document Type: Article

References (23)

1. For reviews on C-H functionalization: a) K. R. Campos, Chem. Soc. Rev. 2007, 36, 1069-1084;
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3. c) M. Lersch, M. Tilset, Chem. Rev. 2005, 105, 2471-2526.
4. For a review of diazo compounds as carbene precursors: H. M. L. Davies, R. E. J. Beckwith, Chem. Rev. 2003, 103, 2861-2903.
5. At 350°C, pivaloyltrimethylsilane undergoes rearrangement and C-H bond insertion to form cyclopropanes; see a) A. R. Bassindale, A. G. Brook, J. Harris, J. Organomet. Chem. 1975, 90, C6-C8;
6. b) A. G. Brook, Acc. Chem. Res. 1974, 7, 77-84.
7. Recent reports of acylsilanes as acyl-anion equivalents: a) R. Unger, T. Cohen, I. Marek, Org. Lett. 2005, 7, 5313-5316;
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16. c) S. P. Pappas, J. B. Blackwell, Jr., Tetrahedron Lett. 1966, 7, 1171-1175.
17. See: a) Microwaves in Organic and Medicinal Chemistry (Eds.: C. O. Kappe, A. Stadler), Wiley-VCH, Weinheim 2005;
18. b) M. Nüchter, B. Ondruschka, W. Bonrath, A. Gum, Green Chem. 2004, 6, 128-141.
19. Removal of the silicon group from 2a results in cis-2,3-dihydro-2-phenylbenzofuran-3-ol (5a), a derivative whose structure was determined by single-crystal X-ray analysis. See the Supporting Information for details.
20. 1H NMR spectroscopy) and 75:25 cis/trans selectivity.
21. Reactions in freshly distilled o-dichlorobenzene afford higher yields presumably because trace water can promote the decomposition of the acylsilane to the aldehyde; see a) A. G. Brook, T. J. D. Vandersar, W. Limburg, Can. J. Chem. 1978, 56, 2758;
22. b) A. G. Brook, N. V. Schwartz, J. Org. Chem. 1962, 27, 2311-2315.
23. See the Supporting Information for structures and spectroscopic data of 1j and 1k.