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U. Gross et al.
LETTER
Vanderheiden, S.; Bräse, S. Adv. Synth. Catal. 2005, 347,
555. (c) Volz, N.; Bröhmer, M. C.; Bräse, S. Synlett 2009,
550. (d) Bröhmer, M. C.; Volz, N.; Bräse, S. Synlett 2009,
1383. (e) For an account, see: Volz, N.; Bröhmer, M. C.;
Toräng, J.; Nieger, M.; Bräse, S. Indian J. Chem., Sect. B:
Org. Chem. Incl. Med. Chem. 2009, 48, 1699.
References and Notes
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(j) Jiang, H.; Gschwend, B.; Albrecht, Ł.; Jørgensen, K. A.
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(11) Typical Procedure
To a round-bottom flask with reflux condenser under argon
atmosphere were added salicylaldehyde (20 mL, 23 mg, 0.19
mmol), crotonaldehyde (23 mL, 19 mg, 0.28 mmol, 1.5
equiv), 1,3-diisopropyl-imidazolium chloride (7.0 mg, 37
mmol, 20 mol%), Cs2CO3 (60 mg, 0.19 mmol, 1.0 equiv) and
o-xylene (1.0 mL). The reaction mixture was heated to 120
°C for 12 h. Then H2O (10 mL) was added, and the resulting
mixture was extracted with EtOAc (3 × 10 mL). The
combined organic extracts were washed with brine (10 ml),
dried over MgSO4, and evaporated under reduced pressure.
Purification by chromatography on silica gel, eluting with
PE–EtOAc (20:1), yielded the desired product 4ac (26 mg,
81%) as a pale yellow solid.
Synlett 2011, No. 5, 635–638 © Thieme Stuttgart · New York