Alkali salt of L-proline as an efficient and practical catalyst for the cyanosilylation of a wide variety of carbonyl compounds under solvent-free conditions

Article abstract of DOI:10.1080/00397910802431149

The alkali salt of L-proline was demonstrated to be an efficient and practical catalyst for the cyanosilylation of a wide variety of simple and functionalized carbonyl compounds under solvent-free conditions. The reactions proceeded smoothly at room temperature to afford the corresponding cyanohydrins in good to excellent yields. Copyright Taylor & Francis Group, LLC.

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Alkali Salt of L-Proline as an
Efficient and Practical Catalyst
for the Cyanosilylation of
a Wide Variety of Carbonyl
Compounds Under Solvent-Free
Conditions
Zhi-Liang Shen a & Shun-Jun Ji a
a Key Laboratory of Organic Synthesis of Jiangsu
Province, College of Chemistry and Chemical
Engineering, Suzhou (Soochow) University, Suzhou,
China
Published online: 29 Jan 2009.
To cite this article: Zhi-Liang Shen & Shun-Jun Ji (2009): Alkali Salt of L-Proline
as an Efficient and Practical Catalyst for the Cyanosilylation of a Wide Variety of
Carbonyl Compounds Under Solvent-Free Conditions, Synthetic Communications: An
International Journal for Rapid Communication of Synthetic Organic Chemistry, 39:5,
775-791
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Synthetic Communications1, 39: 775–791, 2009
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397910802431149
Alkali Salt of L-Proline as an Efficient and
Practical Catalyst for the Cyanosilylation of a
Wide Variety of Carbonyl Compounds Under
Solvent-Free Conditions
Zhi-Liang Shen and Shun-Jun Ji
Key Laboratory of Organic Synthesis of Jiangsu Province, College of
Chemistry and Chemical Engineering, Suzhou (Soochow) University,
Suzhou, China
Abstract: The alkali salt of L-proline was demonstrated to be an efficient
and practical catalyst for the cyanosilylation of a wide variety of simple and func-
tionalized carbonyl compounds under solvent-free conditions. The reactions pro-
ceeded smoothly at room temperature to afford the corresponding cyanohydrins
in good to excellent yields.
Keywords: Cyanohydrin, cyanosilylation, L-proline salt, solvent-free condition,
TMSCN
Cyanohydrins are highly versatile synthetic intermediates that can be
conveniently transformed into various important building blocks, such
as a-hydroxy carbonyl compounds, b-hydroxy amines, and a-amino acid
derivatives.[1] In view of their importance, much attention has been
focused on the development of practical methods for the synthesis of cya-
nohydrins. Among them, the cyanosilylation of carbonyl compounds
using trimethylsilyl cyanide (TMSCN) is widely utilized for the synthesis
of cyanohydrins. Various types of Lewis acids such as I2,[2c] Cu(OTf)2,[2d]
InBr3,[2e] Yb(O3SCF3)3,[2p] and titanium complexes[2j,2k] were used to
Received May 6, 2008.
Address correspondence to Shun-Jun Ji, Key Laboratory of Organic Synthesis
of Jiangsu Province, College of Chemistry and Chemical Engineering, Suzhou
(Soochow) University, Suzhou 215123, China. E-mail: chemjsj@suda.edu.cn
775

776
Z.-L. Shen and S.-J. Ji
promote this transformation. Some types of Lewis bases[2m,2z] or bifunc-
tional catalysts[2a,2k,2w] were also demonstrated to be efficient catalysts
for the mediation of the reaction.[2]
Recently, our group has described efficient and green methods for
the synthesis of cyanohydrins using InF3 in water[3] or simply employing
[4]
immidazolium-based ionic liquid [omim]PF6 as both reaction solvent
and promoter. Although excellent yields were obtained for various alde-
hydes under the reaction conditions, ketones were proven to proceed
sluggishly under the same reaction conditions. In addition, most of the
reported methods for the cyanosilylation of carbonyl compounds are lar-
gely limited to aldehydes as well as more reactive aliphatic ketones.[2]
Poor yields were obtained when the reactions were applied to aryl or
sterically hindered ketones. Therefore, it is still desirable to develop a
more general and practical method for the cyanosilylation of a wide
variety of simple and functionalized carbonyl compounds.
In recent decades, because of the increasing concern about the harmful
effects of organic solvents on the environment and humans, organic reac-
tions that are operated without the participation of conventional organic
solvents have aroused attention of organic chemists because the synthetic
approach is efficient, economical, and environmentally friendly. Many
organic reactions were reported to proceed efficiently under solvent-free
conditions with mild reaction conditions, short reaction times, high yields,
and sometimes enhanced selectivity.[5] Therefore, the application of a
solvent-free synthetic approach to organic synthesis is an important and
continued task worthy of chemists’ attention. Herein, we report an efficient
approach for the synthesis of cyanohydrins via the cyanosilylation of car-
bonyl compounds catalyzed by an alkali salt of L-proline under solvent-
free conditions. This environmentally friendly method, without the use
of volatile and toxic organic solvent, is applicable for various carbonyl
compounds including aryl and sterically hindered carbonyl compounds.
Although there are many reports about the use of L-proline as cata-
lyst in organic reactions, few reports in previous papers concern organic
transformations promoted by an alkali salt of L-proline.[6] In our inves-
tigations, we found that a catalytic amount of potassium salt of L-proline
(10 mol%) could catalyze the cyanosilylation of carbonyl compounds
efficiently under solvent-free conditions (Scheme 1).
Scheme 1. Cyanosilylation of carbonyl compounds under solvent-free conditions.

Alkali Salt of L-Proline
777
Initial study was focused on the reaction of 4-phenyl-3-buten-2-one
with TMSCN in the presence of 10 mol% potassium salt of L-proline
and different solvents. The results are summarized in Table 1.
As shown in Table 1, the cyanosilylation reaction proceeded more effi-
ciently under solvent-free conditions than in organic solvents. The reaction
proceeded smoothly at room temperature to afford the corresponding cya-
nohydrin in 83% yield under solvent-free conditions (Table 1, entry 1).
However, poor yields (<10%) were obtained when water, methanol, and
ionic liquid [hmim]PF6 were used as reaction media (Table 1, entries 8–10).
With the success of the reaction, various aldehydes and ketones were
tested under solvent-free conditions at room temperature. All the results
are summarized in Table 2.
As shown in Table 2, the solvent-free approach works well for
substituted and unsubstituted benzaldehyde (Table 2, entries 1–4) or
acetophenone (Table 2, entries 8–13); good to excellent yields of the cor-
responding products were obtained. In addition, both the cyclic and open
chain aliphatic carbonyl compounds (Table 2, entries 6, 7, and 20–22)
were converted into the corresponding cyanohydrins in good yields. It
should be noted that aromatic and aliphatic a,b-unsaturated carbonyl
Table 1. Potassium salt of L-proline-catalyzed cyanosilylation of 4-phenyl-3-
buten-2-one in different solvents
Entry
Solvent
Yield (%)a
b
1
2
3
—
83
39
80
49
Et2O
CH3CN
THF
4
5
6
CH2Cl2
DMF
56
75
7
8
9
10
DMSO
H2O
MeOH
[hmim]PF6
54
<10
<10
<10
aIsolated yield.
bSolvent-free condition.

778
Z.-L. Shen and S.-J. Ji
Table 2. Potassium salt of L-proline–catalyzed cyanosilylation of various
carbonyl compounds under solvent-free conditions
Entry
1
Carbonyl compound
Product
Yield (%)a
83
2
91
3
4
84
87
5
6
82
90
7
8
73
90
9
89
83
10
11
64
(Continued )

Alkali Salt of L-Proline
779
Table 2. Continued
Entry
12
Carbonyl compound
Product
Yield (%)a
92
13
14
15
90
87
95
16
17
18
78
83
82
19
20
21
85
91
73
22
23
92
99
aIsolated yield.

780
Z.-L. Shen and S.-J. Ji
compounds (Table 2, entries 5 and 17–19) underwent cyanation reaction
efficiently to afford the desired products in good yields; no 1,4-adduct
was observed under the reaction conditions. In the case of 1-indanone
and 1-tetralone (Table 2, entries 15 and 16), they were also proven to
be good substrates for cyanation reaction. Moreover, highly steric hin-
dered substrate benzophenone could also react smoothly with TMSCN
in the presence of the potassium salt of L-proline to afford the corres-
ponding 1,2-adduct in excellent yield (99% yield, Table 2, entry 23).
In the following work, the catalytic activity of a series of alkali salts
of L-proline and its derivatives have been investigated using 4-phenyl-3-
buten-2-one as substrate. The results are outlined in Table 3. Under
Table 3. Different alkali salts of L-proline or its derivatives catalyzed cyanosilyla-
tion of 4-phenyl-3-buten-2-one under solvent-free conditions
Entry
1
Catalyst
Yield (%)a
91
2
3
4
5
6
75
83
82
82
90
7
58
aIsolated yield.

Alkali Salt of L-Proline
781
solvent-free conditions, the best yield (91%) was achieved utilizing lithium
salt of L-proline as catalyst (Table 3, entry 1). However, the use of potas-
sium salt of t-Boc protected L-proline (Table 3, entry 7) gave the product
in only 58% yield. Therefore, it is suggested that both the secondary amine
moiety and the metal carboxylate moiety of alkali salt of L-proline play
important roles for good catalytic activity in the cyanation reaction.
The reaction might proceed via the formation of a hypervalent silicate
between nitrogen and TMSCN to facilitate the progress of the reaction.
In summary, we have developed an efficient and environmentally
friendly protocol for cyanosilylation of variuos carbonyl compounds
employing a catalytic amount of alkali salt of L-proline (10 mol%) under
solvent-free conditions at ambient conditions. This method is quite gen-
eral, and it works well with a wide variety of carbonyl compounds includ-
ing aryl and sterically hindered ketones. The mild reaction conditions, high
yields, good chemoselectivity, cheap catalyst, and environmentally benign
reaction conditions make this method attractive for scale-up purposes.
EXPERIMENTAL
1H NMR and 13C NMR spectra were recorded on a Bruker Avance DPX
300 and Bruker AMX 400 spectrophotometer using tetramethyl silane
(TMS) as an internal standard. High resolution mass spectrometry
(HRMS) spectra were obtained using Finnigan MAT95XP GC=HRMS
(Thermo Electron Corporation). Infrared (IR) spectra were recorded
on a Bio-Rad FTS 165 Fourier transfrom infrared (FTIR) spectrometer.
The alkali salts of L-proline or its derivatives are prepared as follows:
the same equivalents of alkali hydroxide and the corresponding amino acids
were stirred in ethanol for several hours at room temperature; then the sol-
vent was evaporated under reduced pressure, and the remaining solid was
dried at 100 ꢀC in an oven to give the corresponding alkali salt of L-proline.
General Procedure for the Cyanosilylation of Aldehyde
Aldehyde (1 mmol), followed by TMSCN (1 mmol), was added to a
10-mL round-bottomed flask charged with potassium salt of L-proline
(0.1 mmol) at room temperature. After stirring for 12 h, another 1 mmol
TMSCN was added subsequently and stirred for another 12 h. Then 2 mL
THF and 2 mL 1 M aq. HCl were added to the flask, and it was stirred for
a while. Following extraction with diethyl ether (10 mL ꢁ 3), drying over
anhydrous MgSO4, removing of the solvent, and passage through a
column of silica gel gave the desired product, cyanohydrin.

782
Z.-L. Shen and S.-J. Ji
General Procedure for the Cyanosilylation of Ketone
The reaction procedure was the same as cyanosilylation of aldehyde; only
the workup procedure was different. After reaction, excess TMSCN was
removed under reduced pressure, and then the residue was passed
through a column of silica gel directly to give the silylated cyanohydrins.
Spectral and Analytical Data
2-Hydroxy-2-(2-nitrophenyl)acetonitrile (Table 2, Entry 1)[8c]
Rf ¼ 0.18 (ethyl acetate=hexane ¼ 1=4). FTIR (NaCl, neat): n 3397,
1
2249 cmꢂ1. H NMR (300 MHz, CDCl3): d ¼ 4.18 (s, 1H), 6.21 (s, 1H),
7.64 (m, 1H), 7.80 (m, 1H), 7.99 (d, J ¼ 7.65 Hz, 1H), 8.19 (d, J ¼ 8.43 Hz,
Hz, 1H) ppm. 13C NMR (75.4 MHz, CDCl3): d ¼ 146.9, 134.8, 130.9,
130.8, 129.3, 125.8, 117.5, 60.4 ppm. HRMS (ESI, m=z): [M ꢂ H]þ.
Calcd. for C8H5N2O3: 177.0300; found: 177.0306.
2-Hydroxy-2-(4-chlorophenyl)acetonitrile (Table 2, Entry 2)[8a]
Rf ¼ 0.09 (ethyl acetate=hexane ¼ 1=4). FTIR (NaCl, neat): n 3422,
1
2251 cmꢂ1. H NMR (300 MHz, CDCl3): d ¼ 4.72 (s, 1H), 5.47 (s, 1H),
7.37 (d, J ¼ 1.62 Hz, 4H) ppm. 13C NMR (75.4 MHz, CDCl3):
d ¼ 135.6, 133.5, 129.2, 127.9, 118.7, 62.5 ppm. HRMS (EI, m=z): [M]þ.
Calcd. for C8H6ClNO: 167.0138; found: 167.0134.
2-Hydroxy-2-phenylacetonitrile (Table 2, Entry 3)[8a]
Rf ¼ 0.6 (ethyl acetate=hexane ¼ 1=2). FTIR (NaCl, neat): n 3417,
1
2248 cmꢂ1. H NMR (300 MHz, CDCl3): d ¼ 3.74 (br, s, 1H), 5.50 (s,
1H), 7.41–7.52 (m, 5H) ppm. 13C NMR (75.4 MHz, CDCl3): d ¼ 63.4,
118.8, 126.6, 129.1, 129.7, 135.2 ppm. HRMS (EI, m=z): [M]þ. Calcd.
for C8 H7 NO: 133.0528; found: 133.0554.
2-Hydroxy-2-(4-methoxyphenyl)acetonitrile (Table 2, Entry 4)[8a]
Rf ¼ 0.16 (ethyl acetate=hexane ¼ 1=4). FTIR (NaCl, neat): n 3418,
1
2240 cmꢂ1. H NMR (300 MHz, CDCl3): d ¼ 3.80 (s, 3H), 4.04 (s, 1H),
5.42 (s, 1H), 6.91 (d, J ¼ 8.82 Hz, 2H), 7.40 (d, J ¼ 8.43 Hz, 2H) ppm.
13C NMR (75.4 MHz, CDCl3): d ¼ 160.5, 128.2, 127.5, 119.1, 114.4,

Alkali Salt of L-Proline
783
63.0, 55.4 ppm. HRMS (EI, m=z): [M]þ. Calcd. for C9H9NO2: 163.0633;
found: 163.0633.
2-Hydroxy-4-phenyl-3-butenenitrile (Table 2, Entry 5)[8a]
Rf ¼ 0.19 (ethyl acetate=hexane ¼ 1=4). FTIR (NaCl, neat): n 3414,
1
2243 cmꢂ1. H NMR (300 MHz, CDCl3): d ¼ 5.15 (d, J ¼ 5.61 Hz, 1H),
6.25 (d, J ¼ 6 Hz, 1H), 6.90 (d, J ¼ 16.05 Hz, 1H), 7.31–7.42 (m, 5H)
ppm. 13C NMR (75.4 MHz, CDCl3): d ¼ 135.3, 134.8, 129.1, 128.8,
127.1, 122.3, 118.3, 61.9 ppm. HRMS (EI, m=z): [M]þ. Calcd. for
C10H9NO: 159.0684; found: 159.0688.
2-Hydroxy-4-phenylbutanenitrile (Table 2, Entry 6)[8a]
Rf ¼ 0.31 (ethyl acetate=hexane ¼ 1=4). FTIR (NaCl, neat): n 3436,
2247 cmꢂ1
.
1H NMR (300 MHz, CDCl3): d ¼ 2.17 (m, 2H), 2.85 (m,
2H), 4.16 (s, 1H), 4.42 (t, J ¼ 6.81 Hz, 1H), 7.22–7.37 (m, 5H) ppm. 13C
NMR (75.4 MHz, CDCl3): d ¼ 139.6, 128.6, 128.3, 126.4, 120.0, 60.1,
36.4, 30.5 ppm. HRMS (EI, m=z): [M]þ. Calcd. for C10H11NO:
161.0841; found: 161.0843.
2-Hydroxy-n-decanenitrile (Table 2, Entry 7)[8d]
Rf ¼ 0.55 (ethyl acetate=hexane ¼ 1=4). FTIR (NaCl, neat): n 3366,
1
2247 cmꢂ1. H NMR (300 MHz, CDCl3): d ¼ 0.85 (t, J ¼ 6.81 Hz, 3H),
1.24–1.47 (m, 12H), 1.79 (q, J ¼ 6.84 Hz, 2H), 4.17 (s, 1H), 4.42 (t,
J ¼ 6.81 Hz, 1H) ppm. 13C NMR (75.4 MHz, CDCl3): d ¼ 120.2, 61.0,
34.9, 31.7, 29.2, 29.0, 28.8, 24.5, 22.5, 13.9 ppm. HRMS (EI, m=z): [M-
HCN]þ. Calcd. for C9H18O: 142.1358; found: 142.1354.
2-Trimethylsilyloxy-2-(4-nitrophenyl)propanenitrile (Table 2,
Entry 8)[2j,2r]
Rf ¼ 0.48 (ethyl acetate=hexane ¼ 1=6). FTIR (NaCl, neat): n 2237 cmꢂ1
.
1H NMR (300 MHz, CDCl3): d ¼ 0.26 (s, 9H), 1.90 (s, 3H), 7.76 (d,
J ¼ 9.06 Hz, 2H), 8.27 (d, J ¼ 8.7 Hz, 2H) ppm. 13C NMR (75.4 MHz,
CDCl3): d ¼ 0.9, 33.3, 70.9, 120.6, 123.9, 125.7, 148.0, 148.9 ppm.
HRMS (EI, m=z): [M]þ. Calcd. for C12 H16 N2 O3 Si: 264.0930; found:
264.0926.

784
Z.-L. Shen and S.-J. Ji
2-Trimethylsilyloxy-2-(4-chlorophenyl)propanenitrile (Table 2,
Entry 9)[2j,2r]
Rf ¼ 0.70 (ethyl acetate=hexane ¼ 1=6). FTIR (NaCl, neat): n 2236 cmꢂ1
.
1H NMR (300 MHz, CDCl3): d ¼ 0.20 (s, 9H), 1.84 (s, 3H), 7.38 (m, 2H),
7.48 (m, 2H), 8.13 (d, J ¼ 1.59 Hz, 1H) ppm. 13C NMR (75.4 MHz,
CDCl3): d ¼ 1.1, 33.5, 71.1, 121.2, 126.1, 128.8, 134.6, 140.7 ppm. HRMS
(EI, m=z): [M]þ. Calcd. for C12 H16 ClNOSi: 253.0690; found: 253.0689.
2-Trimethylsilyloxy-2-phenylpropanenitrile (Table 2, Entry 10)[2j,2r]
Rf ¼ 0.71 (ethyl acetate=hexane ¼ 1=6). FTIR (NaCl, neat): n 2234 cmꢂ1
.
1H NMR (300 MHz, CDCl3): d ¼ 0.19 (s, 9H), 1.87 (s, 3H), 7.35–7.57
(m, 5H) ppm. 13C NMR (75.4 MHz, CDCl3): d ¼ 1.0, 33.6, 71.6, 121.6,
124.6, 128.6, 142.0 ppm. HRMS (EI, m=z): [M-CH3]þ. Calcd. for
C11H14NOSi: 204.0844; found: 204.0848.
2-Trimethylsilyloxy-2-(4-methylphenyl)propanenitrile (Table 2,
Entry 11)[2j]
Rf ¼ 0.68 (ethyl acetate=hexane ¼ 1=6). FTIR (NaCl, neat): n 2236 cmꢂ1
.
1H NMR (300 MHz, CDCl3): d ¼ 0.20 (s, 9H), 1.86 (s, 3H), 2.38 (s, 3H),
7.22 (d, J ¼ 8.01 Hz, 2H), 7.46 (d, J ¼ 8.43 Hz, 2H) ppm. 13C NMR
(75.4 MHz, CDCl3): d ¼ 1.0, 21.0, 33.4, 71.5, 121.7, 124.5, 129.2, 138.4,
139.1 ppm. HRMS (EI, m=z): [M]þ. Calcd. for C13H19NOSi: 233.1236;
found: 233.1235.
2-Trimethylsilyloxy-2-phenylbutenenitrile (Table 2, Entry 12)[2i]
Rf ¼ 0.67 (ethyl acetate=hexane ¼ 1=6). FTIR (NaCl, neat): n 2235 cmꢂ1
.
1H NMR (300 MHz, CDCl3): d ¼ 0.16 (s, 9H), 0.99 (t, J ¼ 7.43 Hz, 3H),
2.01 (m, 2H), 7.34–7.42 (m, 3H), 7.52 (m, 2H) ppm. 13C NMR
(75.4 MHz, CDCl3): d ¼ 0.9, 8.6, 39.1, 76.2, 120.7, 125.1, 128.4, 128.5,
140.8 ppm. HRMS (EI, m=z): [M]þ, Calcd. for C13H19NOSi: 233.1236;
found: 233.1236.
Benzyl-phenyl-trimethylsiloxy Acetonitrile (Table 2, Entry 13)[8e]
Rf ¼ 0.67 (ethyl acetate=hexane ¼ 1=6). FTIR (NaCl, neat): n 2234 cmꢂ1
7.19–7.56 (m, 10H) ppm. 13C NMR (75.4 MHz, CDCl3): d ¼ ꢂ0.4, 51.0,
.
1H NMR (300 MHz, CDCl3): d ¼ 0.15 (s, 9H), 3.27 (q, J ¼ 15.2 Hz, 2H),

Alkali Salt of L-Proline
785
74.8, 119.2, 124.1, 126.2, 126.7, 127.3, 127.5, 129.8, 133.0, 139.6 ppm.
HRMS (EI, m=z): [M]þ. Calcd. for C18H21NOSi: 295.1392; found:
295.1386.
2-Trimethylsilyloxy-2-(2-naphthyl)propanenitrile (Table 2, Entry 14)[2j]
Rf ¼ 0.58 (ethyl acetate=hexane ¼ 1=6). FTIR (NaCl, neat): n 2234 cmꢂ1
.
1H NMR (300 MHz, CDCl3): d ¼ 0.29 (s, 9H), 2.00 (s, 3H), 7.55–7.60 (m,
2H), 7.69 (dd, J ¼ 8.7, 2.01 Hz, 1H), 7.88–7.96 (m, 3H), 8.13 (d,
J ¼ 1.59 Hz, 1H) ppm. 13C NMR (75.4 MHz, CDCl3): d ¼ 1.0, 33.4,
71.7, 121.5, 122.3, 123.6, 126.6, 126.6, 127.6, 128.3, 128.7, 132.7, 133.1,
139.1 ppm. HRMS (EI, m=z): [M]þ. Calcd. for C16H19NOSi: 269.1236;
found: 269.1236.
2-Trimethylsilyloxy-1,2,3,4-tetrahydronaphthalene-1-carbonitrile
(Table 2, Entry 15)[2j,2r]
Rf ¼ 0.56 (ethyl acetate=hexane ¼ 1=6). FTIR (NaCl, neat): n 2228 cmꢂ1
.
1H NMR (300 MHz, CDCl3): d ¼ 0.27 (s, 9H), 1.94–2.41 (m, 4H), 2.85
(m, 2H), 7.14 (m, 1H), 7.29 (m, 2H), 7.71 (m, 1H) ppm. 13C NMR
(75.4 MHz, CDCl3): d ¼ 1.2, 18.6, 28.2, 37.6, 69.8, 122.0, 126.5, 127.9,
128.9, 129.2, 135.6, 136.0 ppm. HRMS (EI, m=z): [M]þ. Calcd. for
C14H19NOSi: 245.1236; found: 245.1230.
1-Trimethylsilyloxy-1-indancarbonitrile (Table 2, Entry 16)[2j,2r]
Rf ¼ 0.56 (ethyl acetate=hexane ¼ 1=6). FTIR (NaCl, neat): n 2227 cmꢂ1
.
1H NMR (300 MHz, CDCl3): d ¼ 0.21 (s, 9H), 2.45 (m, 1H), 2.72 (m, 1H),
2.94–3.17 (m, 2H), 7.26–7.38 (m, 2H), 7.55 (dd,J ¼ 6.23, 1.59 Hz, 1H)
ppm. 13C NMR (75.4 MHz, CDCl3): d ¼ 1.1, 29.3, 42.8, 76.4, 121.0,
124.0, 125.1, 127.3, 129.9, 142.1, 142.6 ppm. HRMS (EI, m=z): [M]þ.
Calcd. for C13 H17 NOSi: 231.1079; found: 231.1078.
2-Trimethylsilyloxy-2-methyl-4-phenyl-3-butenenitrile (Table 2,
Entry 17)[2j,r]
Rf ¼ 0.63 (ethyl acetate=hexane ¼ 1=6). FTIR (NaCl, neat): n 2236 cmꢂ1
.
1H NMR (300 MHz, CDCl3): d ¼ 0.27 (s, 9H), 1.77 (s, 3H), 6.16 (d,
J ¼ 16.02 Hz, 1H), 6.91 (d, J ¼ 16.02 Hz, 1H), 7.29–7.45 (m, 5H) ppm.
13C NMR (75.4 MHz, CDCl3): d ¼ 1.4, 30.9, 70.0, 120.7, 126.9, 128.6,

786
Z.-L. Shen and S.-J. Ji
128.8, 129.6, 131.0, 135.2 ppm. HRMS (EI, m=z): [M]þ. Calcd. for
C14H19NOSi: 245.1236; found: 245.1236.
2-Trimethylsilyloxy-2-cyclohexenecarbonitrile (Table 2, Entry 18)[2r]
Rf ¼ 0.71 (ethyl acetate=hexane ¼ 1=6). FTIR (NaCl, neat): n 2230 cmꢂ1
.
1H NMR (300 MHz, CDCl3): d ¼ 0.23 (s, 9H), 1.70–2.16 (m, 6H), 5.73 (d,
J ¼ 10.02 Hz, 1H), 5.95 (m, 1H) ppm. 13C NMR (75.4 MHz, CDCl3):
d ¼ 1.5, 18.3, 24.3, 36.9, 66.8, 121.8, 127.6, 132.5 ppm. HRMS (EI,
m=z): [M]þ. Calcd. for C10 H17 NOSi: 195.1079; found: 195.1080.
2,4-Diphenyl-2-trimethylsiloxy-3-but-enenitrile (Table 2, Entry 19)[8b]
Rf ¼ 0.50 (ethyl acetate=hexane ¼ 1=6). FTIR (NaCl, neat): n 2235 cmꢂ1
.
1H NMR (300 MHz, CDCl3): d ¼ 0.38 (s, 9H), 6.32 (d, J ¼ 15.66 Hz, 1H),
7.15 (d, J ¼ 15.66 Hz, 1H), 7.36–7.53 (m, 8H), 7.70–7.73 (m, 2H) ppm.
13C NMR (75.4 MHz, CDCl3): d ¼ 1.2, 75.0, 125.4, 126.9, 128.6, 128.6,
128.8, 129.6, 130.8, 135.0, 140.3 ppm. HRMS (EI, m=z): [M]þ. Calcd.
for C19H21NOSi: 307.1392; found: 307.1390.
2-Trimethylsilyloxy-2-methyl-4-phenyl-3-butanenitrile (Table 2,
Entry 20)[2j]
Rf ¼ 0.65 (ethyl acetate=hexane ¼ 1=6). FTIR (NaCl, neat): n 2232 cmꢂ1
.
1H NMR (300 MHz, CDCl3): d ¼ 0.35 (s, 9H), 1.68 (s, 3H), 2.09 (m,
2H), 2.90 (m, 2H), 7.24–7.38 (m, 5H) ppm. 13C NMR (75.4 MHz, CDCl3):
d ¼ 1.2, 28.9, 30.6, 45.1, 69.3, 121.7, 126.1, 128.2, 128.4, 140.6 ppm. HRMS
(EI, m=z): [M]þ. Calcd. for C14H21NOSi: 247.1392; found: 247.1391.
1-Trimethylsilyloxy-1-cyclohexanecarbonitrile (Table 2, Entry 21)[2r]
Rf ¼ 0.75 (ethyl acetate=hexane ¼ 1=6). FTIR (NaCl, neat): n 2233 cmꢂ1
.
1H NMR (300 MHz, CDCl3): d ¼ 0.22 (s, 9H), 1.51–1.76 (m, 8H), 2.03 (t,
J ¼ 7.64 Hz, 2H) ppm. 13C NMR (75.4 MHz, CDCl3): d ¼ 1.4, 22.6, 24.5,
39.3, 70.6, 121.9 ppm. HRMS (EI, m=z): [M]þ. Calcd. for C10H19NOSi:
197.1236; found: 197.1238.
Dibenzyl-trimethylsiloxy-acetonitrile (Table 2, entry 22)[8f]
Rf ¼ 0.60 (ethyl acetate=hexane ¼ 1=6). FTIR (NaCl, neat): n 2232 cmꢂ1
.
1H NMR (300 MHz, CDCl3): d ¼ꢂ0.04 (s, 9H), 3.10 (s, 4H), 7.40

Alkali Salt of L-Proline
787
(m, 10H) ppm. 13C NMR (75.4 MHz, CDCl3): d ¼ 0.3, 47.8, 73.4, 120.2,
127.3, 128.1, 130.9, 134.4 ppm. HRMS (EI, m=z): [M]þ. Calcd. for
C19H23NOSi: 309.1549; found: 309.1550.
Diphenyl-trimethylsiloxy-acetonitrile (Table 2, Entry 23)[8e]
Rf ¼ 0.55 (ethyl acetate=hexane ¼ 1=6). FTIR (NaCl, neat): n 2234 cmꢂ1
.
1H NMR (300 MHz, CDCl3): d ¼ 0.18 (s, 9H), 7.33–7.41 (m, 6H), 7.52–
7.56 (m, 4H) ppm. 13C NMR (75.4 MHz, CDCl3): d ¼ 141.9, 128.6,
128.5, 125.9, 120.7, 76.4, 0.9 ppm. HRMS (EI, m=z): [M]þ. Calcd. for
C17H19NOSi: 281.1236; found: 281.1237.
ACKNOWLEDGMENT
This work was partially supported by the Key Laboratory of Organic
Synthesis of Jiangsu Province at Suzhou University (No. S8109108),
the Natural Science Foundation of Jiangsu Province (No. BK2006048),
the National Science Foundation of China (Nos. 20472062 and
20672079), the Nature Science Key Basic Research of Jiangsu Province
for Higher Education (Nos. 06KJA15007 and 05KJB150116), the Jiangsu
Provincial Key Laboratory of Fine Petrochemical Technology (KF0402),
and a research grant from the Innovation Project for Graduate Students
of Jiangsu Province.
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