Categories: C=C Bond Formation >
Synthesis of enamines, enamides and related compounds
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Recent Literature

A facile and practical method for the synthesis of N-acetyl
α-arylenamides from the corresponding ketoximes with ferrous acetate as the
reducing reagent offers mild reaction conditions, simple purification procedures,
and high yields for a variety of N-acetyl enamides.
W. Tang, A. Capacci, M. Sarvestani, X. Wei, N. K. Yee, C. H. Senanayake, J. Org. Chem., 2009,
74, 9528-9530.

A new synthesis of enamides from ketones involves a phosphine-mediated reductive
acylation of oximes. The resulting enamides are isolated in good yields and
excellent purity.
H. Zhao, C. P. Vandenbossche, S. G. Koenig, S. P. Singh, R. P. Bakale, Org. Lett., 2008,
10, 505-507.

Among the reported examples of new reactivity of the hypervalent iodine
reagent DMP (Dess-Martin periodinane) are the one-step oxidation of
secondary amides to imides and N-acyl vinylogous carbamates or ureas
and the direct oxidation of benzylic and related primary amines to the
corresponding nitriles.
K. C. Nicolaou, C. J. N. Mathison, Angew. Chem. Int. Ed., 2005,
44, 5992-5997.

Slow addition of 3 - 5 eq. of α-bromo esters to aliphatic or aromatic
nitriles in the presence of activated zinc in refluxing tetrahydrofuran yielded
the corresponding enamino esters or, after acid hydrolysis, β-keto esters.
Slow addition and use of tetrahydrofuran as solvent substantially improved the
yield of the Blaise reaction and also enabled the conversion of bromoacetates to
give α-unsubtituted products.
S. M. Hannick, Y. Kishi, J. Org. Chem., 1983,
48, 3833-3835.

β-Amino-α,β-unsaturated esters are produced by a sonochemical Blaise reaction of
nitriles, zinc powder, zinc oxide and ethyl bromoacetate in THF in a commercial
ultrasonic cleaning bath.
A. S.-Y. Lee, R.-Y. Cheng, Tetrahedron Lett., 1997,
38, 443-446.

Reaction of aryl nitriles with potassium ethyl malonate in the presence of zinc
chloride and a catalytic amount of Hünig's base provided β-amino acrylates in
moderate to good yield. Compared to the classical Blaise reaction, this reaction
is safer, devoid of lachrymatory reagent, and is possible with less zinc
chloride.
J. H. Lee, B. S. Choi, J. H. Chang, H. B. Lee, J.-Y. Yoon, J. Lee, H. Shin,
J. Org. Chem., 2007,
72, 10261-10263.

The in situ generated Blaise reaction intermediate, a zinc bromide complex of
β-enaminoester, reacts with various alkynes under mild conditions to afford
α-vinylated β-enaminoesters in good to excellent yields.
Y. S. Chun, Y. O. Ko, H. Shin, S.-g. Lee, Org. Lett., 2009,
11, 3414-3417.

α,β-Dehydroamino acid derivatives were synthesized in good yields from
α-bromoketones or α-bromoesters and hydroxamates via a sequential procedure
involving displacement of bromide by hydroxamate anion, followed by a
base-induced elimination-isomerization reaction.
Y. Sun, X. Wang, X. Zheng, K. Zhao, Synlett, 2008,
861-866.
