Stereoselective Synthesis of (E)-Cinnamonitriles with the SmI2/THF/MeOH System

Article abstract of DOI:10.1039/a900130a

α-Phenylsulfonylcinnamonitriles are readily reduced by SmI2/THF/MeOH to give the corresponding (E)-cinnamonitriles in good yields under mild conditions.

Full text of DOI:10.1039/a900130a

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3
42 J. CHEM. RESEARCH (S), 1999
J. Chem. Research (S),
Stereoselective Synthesis of (E)-Cinnamonitriles
1
999, 342^343y
with the SmI /THF/MeOH Systemy
2
Hongyun Guo and Yongmin Zhang*
Department of Chemistry, Zhejiang University at Xixi Campus, Hangzhou, 310028, P. R. China
a-Phenylsulfonylcinnamonitriles are readily reduced by SmI2/THF/MeOH to give the corresponding (E)-cinnamonitriles
in good yields under mild conditions.
Cinnamonitriles are important intermediates of organic
synthesis. Cinnamoacids and a,b-unsaturated acylamides
were obtained by hydrolysis of cinnamonitriles. The saturated
nitriles can be prepared by the selective reduction of cin-
namonitriles. Many methods can be used for the synthesis
of cinnamonitriles, such as the reaction of cinnamaldehyde
under mild conditions (Scheme 1). Some results are
summarized in Table 1.
Ar
H
CN
SmI2/THF/MeOH
r.t., 6–8 h
C
C
ArCH
C
H
CN
SO Ph
2
1
and dimethylsulfur diimide, by the reaction of the thallium
2
reagent ArTlꢀO2CCCl3† ; by Wittig^Horner reaction of
Scheme 1
2
3
ꢀ
EtO† POCH2CN and aldehyde, the treatment of acid chlor-
2
4
ide with sulfonamide and the condensation of aldehyde and
Table 1 shows that a-phenylsulfonylcinnamonitriles undergo
reductive desulfonation in the presence of samarium diiodide
in THF-MeOH solution to give the corresponding (E)-
cinnamonitriles in moderate to good yields at room
temperature. The chloro and bromo group of the aromatic
ring have no e¡ect on the desulfonylation. IR spectra show
5
nitroethane.
Samarium diiodide (SmI2) is a powerful one-electron
6
transfer reductant but which cannot reduce the cyano
7
8
group. Recently, Huang et al. reported that (Z)-
cinnamonitriles were prepared in 78^98% yield by the
desulfonylaton of a-phenylsulfonylcinnamonitriles in the
presence of NaHTe. This prompted us to use SmI2 for the
desulfonylation of a-phenylsulfonylcinnamonitriles. We found
that (E)-cinnamonitriles were obtained in 68^85% yield
1
that the sulfonyl group (SO ) is lost. H NMR spectra show
2
that (Z)-cinnamonitriles (J ˆ 6^12 Hz) have not been formed
in the crude products of the reaction. All products gave sat-
1
isfactory mp, IR and H NMR spectra.
Table 1 Synthesis of (E)-cinnamonitriles with SmI2/THF/MeOH
Mp/8C
IR (neat or KBr)
1H NMR (CCl4 or CDCl3),
d (J/Hz)
�
1
Entry
Ar
Yield*(%)
(lit.)
(cm
)
a
C6H5
68
18^20
2212, 1630,
1330, 965
5.60 (d, 1 H, J ˆ 16:5)
7.26 (d, 1 H, J ˆ 16:5)
9
(
22.5)
7
.30 (s, 5 H)
b
c
p-MeC6H4
m-MeC6H4
85
79
68^70
70^71)
2215, 1633,
1380, 1300, 965
2.26 (s, 3H)
1
0
(
5.43 (d, 1 H, J ˆ 16:7)
7
6
.15 (d, 1 H, J ˆ 16:7)
.10^7.30 (m, 4 H)
Oil10
2210, 1617,
2.23 (s, 3 H)
1
380, 1317, 967
5.63 (d, 1 H, J ˆ 16:6)
7
7
.13 (d, 1 H, J ˆ 16:6)
.06 (s, 4 H)
d
e
f
p-ClC6H4
o-ClC6H4
p-MeOC3H4
74
71
73
81^83
2217, 1635,
1315, 965, 800
5.43 (d, 1 H, J ˆ 16:7†
1
1
0
2
(
84^85)
7.27 (d, 1 H, J ˆ 16:7)
7
.30 (s, 4 H)
38^40
41^42)
2215, 1627,
1314, 967, 772
5.56 (d, 1 H, J ˆ 16:5)
(
7.12 (d, 1 H, J ˆ 16:5)
7
.24 (s, 4 H)
62^64
2210, 1618,
1380, 1310, 965
3.76 (s, 3 H)
10
(
64)
5.50 (d, 1 H, J ˆ 16:5)
7
6
.20 (d, 1 H, J ˆ 16:5)
.56^7.33 (m, 4 H)
g
h
p-BrC6H4
70
76
102^104
105^106)
2215, 1637,
1312, 968, 778
5.56 (d, 1 H, J ˆ 16:4)
1
0
1
(
7.26 (d, 1 H, J ˆ 16:4)
7
.30 (s, 4 H)
p-Me2NC6H4
165^168
168^169)
2210, 1615,
1380, 1318, 970
2.97 (s, 6 H)
1
(
5.43 (d, 1 H, J ˆ 16:6)
6
6
.70 (d, 1 H, J ˆ 16:6)
.40^7.15 (m, 4 H)
*
Isolated yields.
In conclusion, with its chemoselectivity, stereoselectivity,
*
To receive any correspondence.
mild and neutral condition, as well as simple operation,
we think that the present procedure may be useful for the
synthesis of (E)-cinnamonitriles.
y This is a Short Paper as de¢ned in the Instructions for Authors,
Section 5.0 [see J. Chem. Research (S), 1999, Issue 1]; there is
therefore no corresponding material in J. Chem. Research (M).

View Article Online
J. CHEM. RESEARCH (S), 1999 343
Experimental
Received, 5th January 1999; Accepted, 10th February 1999
Paper E/9/00130A
Tetrahydrofuran (THF) was freshly distilled from sodium^
benzophenone prior to its use. MeOH was puri¢ed by distillation.
1
IR spectra were recorded on a PE-683 spectrometer, H NMR spectra
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We thank the National Natural Science Foundation of
China (Project No. 29872010), laboratory of Organometallic
Chemistry, Shanghai Institute of Organic Chemistry, Chinese
Academy of Science and NSF of Zhejiang Province, China
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