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Organocatalytic stereoselective one-pot synthesis of highly functionalized cyclohexanones
No full textThe objective of our work is to present a new synthetic application of beta-nitroacrylates, substrates that are gaining
increasing importance as precursors of highly functionalized intermediates.1 Different 3-alkyl substituted nitro
ethylacrylates may be easily synthesized through nitro aldol condensation between the proper nitroalkane and ethyl
glyoxylate, followed by reaction with mesyl chloride and treatment with a base to afford the desired product isolated
with a single chromatographic purification.2
We exploited chiral primary amine catalysis to obtain highly functionalized cyclohexanone derivatives starting from
alfa,beta-unsaturated ketones and beta-nitroacrylates; the use of 9-deoxy-epicinchona alkaloids, that have already
proved to be very effective catalysts in lots of different transformations3, in the presence of an acidic co-catalyst
allowed to obtain cyclohexanone rings endowed with three stereogenic centers with complete regionselectivity and
high enantiomeric excess. In particular, the reaction between (E)-4-phenyl-3-buten-2-one and (E)-ethyl-3-nitropent-
2-enoate, catalyzed by 9-amino-9-deoxy-epi-quinine and salicylic acid, gave product 1 in 70% yield, with an
endo/exo ratio of 1:3 and 96.5% and 95% enantiomeric excess for the two diastereoisomers, respectively. The
reaction promoted by the quasi-enantiomer catalyst 9-amino-9-deoxy-epi-quinidine afforded the desired product in
comparable yields and stereoselectivity, showing an opposite sense of enantioselection.The reaction proceeds through a dienamine catalyzed pathway4; this kind of activation has already been used to
perform Diels-Alder reactions between cyclohexenone and nitrostirene.5 The mechanism through which the dienamine
intermediate reacts with beta-nitroacrylates is still uncertain, as there are no conclusive evidence to support a [4+2]
cycloaddition pathway rather than a double-Michael addition cascade sequence.references:1 H. Ishikawa, T. Suzuki, H. Orita, T. Uchimaru, Y. Hayashi, Chem. Eur. J., 2010, 16, 12616-12626.
2 R. Ballini, D. Fiorini, A. Palmieri, Tetrahedron Lett., 2004, 45, 7027-7029.
3 Melchiorre, Angew. Chem. Int. Ed., 2012, 51, 9748-9770.
4 L.-Y Wu, G. Bencivenni, M. Mancinelli, A. Mazzanti, G. Bartoli, P. Melchiorre, Angew. Chem. Int. Ed., 2009, 48, 7196-7199.
5 G. N. Stowe, K. D. Janda, Tetrahedron Lett., 2001, 52, 2085-2087
A. Palmieri, I pellegrinaggi russi in Terrasanta, Extrait du Bessarione
No full textPargoire Jules. A. Palmieri, I pellegrinaggi russi in Terrasanta, Extrait du Bessarione. In: Échos d'Orient, tome 5, n°1, 1901. p. 64
A. Palmieri, Dagli archivi dei Conventuali di Constantinopoli. Extrait du Bessarione
No full textPargoire Jules. A. Palmieri, Dagli archivi dei Conventuali di Constantinopoli. Extrait du Bessarione. In: Échos d'Orient, tome 5, n°1, 1901. p. 64
A. Palmieri, Les Frères des Ecoles chrétiennes en Orient. Extrait du Bessarione
No full textBousquet R. A. Palmieri, Les Frères des Ecoles chrétiennes en Orient. Extrait du Bessarione. In: Échos d'Orient, tome 5, n°1, 1901. pp. 63-64
A. Palmieri : La conversione officiale degl'Iberi al cristianesimo. Extrait de l'Oriens christianus, 1902.
No full textSouarn Romuald. A. Palmieri : La conversione officiale degl'Iberi al cristianesimo. Extrait de l'Oriens christianus, 1902.. In: Échos d'Orient, tome 7, n°46, 1904. pp. 187-188
A. Palmieri, O. S. Α., Il progresso dommatico nel concetto cattolico.
No full textJugie M. A. Palmieri, O. S. Α., Il progresso dommatico nel concetto cattolico. . In: Échos d'Orient, tome 13, n°84, 1910. p. 314
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