Chiral Quaternary Ammonium Aryloxide/N,O-Bis(trimethylsilyl)acetamide Combination
Acknowledgements
This work was supported by CNRS, University and INSA of
Rouen, the Rꢀgion Haute-Normandie and the Labex SynOrg
(ANR-11-LABX-0029). A. C. thanks the CRUNCH network
for a grant.
References
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2026–2029. For asymmetric organocatalytic Mannich
addition of (5H)-furan-2-one derivatives, see: f) Y.-L.
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Luo, F. Tian, X.-Y. Xu, L.-X. Wang, J. Org. Chem.
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Figure 4. Mechanism proposal.
Experimental Section
General Procedure for the Organocatalytic Direct
Vinylogous Aldol Reaction
To a solution of QN+8, BrÀ (0.05 mmol, 30.4 mg) in THF
(3 mL) at room temperature was added sodium 4-methoxy-
phenoxide freshly prepared as a solution in THF (1M,
0.04 mmol, 40 mL). The whole was stirred for 1 hour at this
temperature, after which the (5H)-furan-2-one derivatives
2a–c (0.5 mmol) was added. The resulting mixture was
cooled to the required temperature and aldehyde
(0.75 mmol) and BSA (0.75 mmol, 184 mL) were added and
the solution was stirred at the same temperature for the
specified time for each individual compound. An aqueous
solution of HCl (10%, 0.5 mL) was added and the reaction
flask was placed at 08C. The resulting mixture was stirred
for 30 min at this temperature. Water was added (2 mL) and
the mixture was extracted with AcOEt (2ꢄ4 mL). The aque-
ous phase was neutralized with saturated aqueous NaHCO3
solution and extracted with AcOEt (5 mL). The combined
organic phases were washed with brine (10 mL), dried over
Na2SO4 and concentrated under reduced pressure. The
crude reaction mixture was purified by column chromatog-
raphy on silica gel by using petroleum ether/AcOEt and
subjected to HPLC analysis using chiral column.
[6] For a review on asymmetric PTC, see : T. Hashimoto,
K. Maruoka, Chem. Rev. 2007, 107, 5656–5682.
Adv. Synth. Catal. 0000, 000, 0 – 0
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