693
This work was partially supported by the Naito Foundation.
(ADMP, 1) (309 mg, 1.2 mmol) in MeCN (5 mL), and silyl
enol ether 5a (192 mg, 1.0 mmol) in MeCN (5 mL) were
added at room temperature and the reaction mixture was
stirred for 5 h at reflux temperature. The reaction was
quenched with NaHCO3 (aq) (5 mL) and the organic
materials were extracted with CH2Cl2 (3 © 10 mL). The
combined extracts were washed with brine (2 mL), and then
dried over anhydrous Na2SO4. The solvent was removed in
vacuo to afford crude compounds, which were purified by
flash column chromatography (SiO2: CHCl3/MeOH = 14/
1) to give the pure migratory-amidated compound 6a in 73%
This paper is dedicated to Professor Teruaki
Mukaiyama in celebration of the 40th anniversary of the
Mukaiyama aldol reaction.
References and Notes
1
2
M. B. Smith, J. March, March’s Advanced Organic
Chemistry, John Wiley & Sons, New Jersey, 2007, Chpt. 10,
p. 587.
M. B. Smith, J. March, March’s Advanced Organic
Chemistry, John Wiley & Sons, New Jersey, 2007, Chpt. 13,
p. 906.
For a review, see: C. C. C. Johansson, T. J. Colacot, Angew.
Our recent study on the reaction of 2-azido-1,3-dimethyl-
imidazolinium salt, see: a) M. Kitamura, T. Koga, M. Yano,
Kitamura, M. Yano, N. Tashiro, S. Miyagawa, M. Sando, T.
Kitamura, N. Tashiro, Y. Takamoto, T. Okauchi, Chem. Lett.
1
yield. Spectral data for 6a: H NMR (300 MHz, CDCl3): ¤
7.38 (d, 2H, J = 7.2 Hz), 7.32-7.24 (m, 2H), 7.22-7.16 (m,
1H), 3.64 (s, 2H), 3.50 (s, 4H), 2.77 (s, 6H); 13C NMR
(126 MHz, CDCl3): 176.6, 163.7, 138.2, 129.2, 128.0, 125.9,
47.2, 47.0, 33.2; IR (KBr): 2939, 2886, 2202, 1587, 1398,
1294, 1035 cm¹1. Anal. Calcd for C13H17N3O (231.14): C,
67.51; H, 7.41; N, 18.17%. Found: C, 67.48; H, 7.38; N,
18.09%.
3
4
5
10 Typical procedure for the transformation of 6 to 8 by the
treatment of LiAlH4. Synthesis of 8a (Table 2, Run 1, step
2): To a suspension of LiAlH4 (15 mg, 0.40 mmol) in THF
(2 mL), amide 6a (92 mg, 0.40 mmol) in THF (2 mL) was
added at 0 °C and the reaction mixture was stirred for 10 min.
The reaction was quenched by adding water (3 mL) slowly,
and the mixture was filtered through a Celite pad. The
organic materials were extracted with EtOAc (3 © 10 mL).
The combined extracts were washed with water (2 © 20 mL)
and brine (20 mL), and then dried over anhydrous Na2SO4.
The solvent was removed in vacuo to afford crude
compounds, which were purified by flash column chroma-
tography (SiO2: CHCl3/MeOH = 19/1) to give the pure
phenylacetamide 8a in 90% yield. Spectral data for 8a:11
1H NMR (300 MHz, CDCl3): ¤ 7.41-7.26 (m, 5H), 5.60-
5.15 (br, 2H), 3.60 (s, 2H); 13C NMR (126 MHz, CDCl3):
173.2, 134.8, 129.4, 129.1, 127.5, 43.3.
6
7
ADMP 1 is a crystalline reagent having high thermal
stability and low explosibility5b,5c and is now commercially
available from TCI (cat. No. A2457).
For example, in the reaction of acetophenone and ADMP 1
in THF in the presence of Et3N, DBU, or LDA at various
reaction temperatures, migratory-amidated compound was
not obtained and acetophenone was recovered in 70-95%.
The pioneer reaction using silyl enol ether: Mukaiyama aldol
reaction, see: a) T. Mukaiyama, K. Narasaka, K. Banno,
Typical procedure for the synthesis of amide 6 by the
reaction of silyl enol ethers of alkyl aryl ketones 5 and
ADMP 1. Synthesis of 6a (Table 1, Run 2): To a solution
of 2-azido-1,3-dimethylimidazolinium hexafluorophosphate
8
9
11 a) W. Wenner, Org. Synth. Coll. Vol. 1963, 4, 760. b) K.
Chem. Lett. 2013, 42, 691-693
© 2013 The Chemical Society of Japan