Diana Almas¸i et al.
COMMUNICATIONS
Ohara, H. Yoda, K. Takabe, F. Tanaka, C. F. Barbas III,
J. Am. Chem. Soc. 2006, 128, 734–735; f) N. Mase, K.
Watanabe, H. Yoda, K. Takabe, F. Tanaka, C. F. Barbas
III, J. Am. Chem. Soc. 2006, 128, 4966–4967; g) Y. Hay-
ashi, S. Aratake, T. Okano, J. Takahashi, T. Sumiya, M.
Shoji, Angew. Chem. Int. Ed. 2006, 45, 5527–5529;
h) Y. Hayashi, T. Sumiya, J. Takahashi, H. Gotoh, T.
Urushima, M. Shoji, Angew. Chem. Int. Ed. 2006, 45,
958–961.
Typical Procedure for the Intermolecular Aldol
Reaction and Recovery of the Catalyst 3d:
Conventional Magnetic Stirring conditions (Table 1,
entry 8)
A mixture of the catalyst 3d (30 mg, 0.122 mmol), 4-nitroben-
zoic acid (20.5 mg, 0.122 mmol) and cyclohexanone (508 mL,
4.88 mmol) was stirred for 20 min at 08C. Then, 4-nitroben-
zaldehyde (368.4 mg, 2.44 mmol) was added and the reaction
mixture was stirred at 08C. After 8 h water (20 mL), EtOAc
(20 mL) and HCl 10% (127.14 mL, 0.366 mmol) were added
to the reaction mixture. After separation, the organic layer
was dried over anhydrous MgSO4, filtered off and the solvent
was evaporated under reduced pressure to give a crude that
was purified by flash chromatography (silica gel, hexane/
EtOAc: 1/6) to afford pure product anti 5aa.
The aqueous layer was treated with NaOH 10% solution
(480 mL, 1.464 mmol) and then extracted with EtOAc (3ꢄ
20 mL). The resulting organic layers were dried over anhy-
drous MgSO4, filtered off and the solvent was evaporated at
low pressure to give a crude residue that was purified by re-
crystallization giving pure organocatalyst 3d; yield: 27 mg
(90%); {[a]2D0: +113 (c 1.0, CH2Cl2}.
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chemistry: Chem. Rev. 2007, 107, 2167–2820; d) B. Ro-
drꢁguez, A. Bruckmann, T. Rantanen, C. Bolm, Adv.
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[5] R. Mahrwald, Modern Aldol Reactions, Wiley-VCH,
Weinhem, 2004, Vols. 1 and 2.
[6] a) G. Guillena, C. Najera, D. J. Ramon, Tetrahedron:
Asymmetry 2007, 18, 2249–2293; b) C. Allemann, R.
Gordillo, F. R. Clemente, P. H.-Y. Cheong, K. N. Houk,
Acc. Chem. Res. 2004, 37, 558–569; c) H. Groger, J.
Wilken, Angew. Chem. Int. Ed. 2001, 40, 529–532; d) S.
Doye, Chemie in Unserer Zeit 2001, 35, 62–63; e) B.
List, Synlett 2001, 1675–1686; f) M. Movassaghi, E. N.
Jacobsen, Science 2002, 298, 1904–1905; g) E. J. Soren-
sen, G. M. Sammis, Science 2004, 305, 1725–1726; h) S.
Saito, H. Yamamoto, Acc. Chem. Res. 2004, 37, 570–
579; i) W. Notz, F. Tanaka, C. F. Barbas III, Acc. Chem.
Res. 2004, 37, 580–591; j) U. Kazmaier, Angew. Chem.
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[7] a) B. Rodriguez, T. Rantanen, C. Bolm, Angew. Chem.
Int. Ed. 2006, 45, 6924–6926; b) B. Rodriguez, A.
Bruckmann, C. Bolm, Chem. Eur. J. 2007, 13, 4710–
4722; c) Y. Hayashi, S. Aratake, T. Itoh, T. Okano, T.
Sumiya, M. Shoji, Chem. Commun. 2007, 957–958;
d) G. Guillena, M. C. Hita, C. Nꢀjera, S. F. Viꢅzquez,
Tetrahedron: Asymmetry 2007, 18, 2300–2304.
Supporting Information
Additional experimental procedures, spectra data for new
compounds and intermediates, as well as HPLC separation
conditions and retention times for compounds 5 and 7 are
available as Supporting Information.
Acknowledgements
Financial support from the MEC (Projects CTQ2004-00808/
BQU, CTQ2007–62771/BQU and Consolider INGENIO
2010 CSD2007–00006), from the Generalitat Valenciana
(GRUPOS05/11, GV05/144, GV/2007/142) and the Universi-
ty of Alicante are acknowledged. D. A. thanks the EU and
the Spanish MEC for a predoctoral fellowship
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