Categories: C-C Bond Formation > Nitrogen-containing molecules >
Synthesis of Cyanohydrins
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Recent Literature
Chiral oxazaborolidinium salts are excellent catalysts for a highly
enantioselective cyanosilylation of various aldehydes using trimethylsilyl
cyanide and triphenylphosphine oxide as the source of a new reactive cyanide
donor. A mechanistic model allows the prediction of the absolute
configuration of cyanohydrin products.
D. H. Ryu, E. J. Corey, J. Am. Chem. Soc.,
2004,
126, 8106-8107.
A new chiral amino thiourea catalyst promotes the highly enantioselective
cyanosilylation of a wide variety of ketones. The hindered tertiary amine
substituent plays a crucial role with regard to both stereoinduction and
reactivity, suggesting a cooperative mechanism involving electrophile
activation by thiourea and nucleophile activation by the amine.
D. E. Fuerst, E. N. Jacobsen, J. Am. Chem. Soc.,
2005,
127, 8964-8965.
A β-amino alcohol-Ti(Oi-Pr)4 complex efficiently catalyzes
a mild, enantioselective cyanosilylation of aldehydes. Aromatic, conjugated, heteroaromatic, and aliphatic aldehydes were
converted to their corresponding cyanohydrin trimethylsilyl ethers in excellent yields with
high enantioselectivities.
Y. Li, B. He, B. Qin, X. Feng, G. Zhang, J. Org. Chem., 2004,
69, 7910-7913.
A simple, inexpensive, and highly enantioselective cyanohydrin synthesis
with aromatic aldehydes using chiral lithium binaphtholate aqua or alcohol
complexes has been developed that is suitable for process chemistry.
Dramatic improvements in enantiomeric excess have been realized along with
an interesting changeover in absolute stereochemistry of cyanohydrin product
against the thoroughly "dry" catalytic systems.
M. Hatano, T. Ikeno, T. Miyamoto, K. Ishihara, J. Am. Chem. Soc.,
2005,
127, 10776-10777.
1-Methoxy-2-methyl-1-(trimethylsiloxy)propene, a neutral π-nucleophile, is able
to efficiently catalyze cyanosilylations and cyanocarbonations of various
aldehydes and ketones.
X. Wang, S.-K. Tian, Synlett, 2007,
1416-1420.
1-Methoxy-2-methyl-1-(trimethylsiloxy)propene, a neutral π-nucleophile, is able
to efficiently catalyze cyanosilylations and cyanocarbonations of various
aldehydes and ketones.
X. Wang, S.-K. Tian, Synlett, 2007,
1416-1420.
An efficient, simple and mild method enables a cyano transfer from
trimethylsilylcyanide (TMSCN) to aldehydes within 10 minutes at room temperature
in the presence of 0.5 mol% of dispersed NbF5 as the catalyst
under solvent-free conditions giving cyanohydrins in excellent yields.
S. S. Kim, G. Rajagopal, Synthesis, 2007, 215-218.
Tertiary cyanohydrin trimethylsilyl ethers were synthesized in excellent yields
by using a catalytic-amount of a salen-Al complex and an N-oxide without
solvent at ambient temperature. Transition states for double-activation
catalysis were proposed.
F.-X. Chen, X. Liu, B. Qin, H. Zhou, X. Feng, G. Zhang, Synthesis,
2004, 2266-2272.
N-Heterocyclic carbenes were found to be highly effective organocatalysts in
activating TMSCN for facile and mild cyanosilylation of carbonyl compounds.
Various trimethylsilylated cyanohydrins were isolated in very good to
excellent yields.
J. J. Song, F. Gallou, J. T. Reeves, Z. Tan, N. K. Yee, C. H. Senanayake,
J. Org. Chem.,
2006,
71, 1273-1276.
An efficient method for achiral addition of TMSCN to ketones employs N-methylmorpholine
N-oxide as catalyst. A variety of aromatic, aliphatic, cyclic and
heterocyclic ketones are converted into their corresponding trimethylsilyl
ethers in excellent yields (>90%).
Z.-G. Le, Z.-C. Chen, Y. Hu, Q.-G. Zheng, Synthesis, 2004,
208-212.
An N-heterocyclic carbene as a nucleophilic organocatalyst allows the
cyanation of ketones and ketimines with TMSCN in good yields under mild
reaction conditions.
Y. Fukuda, K. Kondo, T. Aoyama,
Synthesis, 2006, 2649-2652.
Combinations of N-oxides and Ti(OiPr)4 act as
bifunctional catalysts in the cyanosilylation of ketones. The reaction is
promoted by the dual action of these new titanium complexes via activation
of the ketone by the titanium and of TMSCN by the N-oxide.
Y. Shen, X. Feng, Y. Li, G. Zhang, Y. Jiang, Tetrahedron, 2003,
59, 5667-6675.
A bimetallic titanium complex [(salen)TiO]2 catalyzes the asymmetric addition of ethyl cyanoformate to aldehydes leading to
cyanohydrin carbonates with high enantiomeric excesses.
Y. N. Belokon, A. J. Blacker, L. A. Clutterbuck, M. North, Org. Lett.,
2003,
5, 4505-4507.
