Potassium hydroxide-promoted selective N -monoalkylation of chiral t -butane- and p -toluenesulfinamides

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Potassium Hydroxide-promoted Selective
N-Monoalkylation of Chiral t-Butane- and
p-Toluenesulfinamides
Xirui Lva, Qinjie Xianga & Qingle Zenga
a Institute of Green Catalysis and Synthesis, College of Materials
and Chemistry & Chemical Engineering, Chengdu University of
Technology, Chengdu 610059, P. R. China
Published online: 26 Mar 2014.
To cite this article: Xirui Lv, Qinjie Xiang & Qingle Zeng (2014) Potassium Hydroxide-promoted
Selective N-Monoalkylation of Chiral t-Butane- and p-Toluenesulfinamides, Organic Preparations
and Procedures International: The New Journal for Organic Synthesis, 46:2, 164-175, DOI:
10.1080/00304948.2014.884373
To link to this article: http://dx.doi.org/10.1080/00304948.2014.884373
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Organic Preparations and Procedures International, 46:164–175, 2014
Copyright © Taylor & Francis Group, LLC
ISSN: 0030-4948 print / 1945-5453 online
DOI: 10.1080/00304948.2014.884373
Potassium Hydroxide-promoted Selective
N-Monoalkylation of Chiral t-Butane-
and p-Toluenesulfinamides
Xirui Lv, Qinjie Xiang, and Qingle Zeng
Institute of Green Catalysis and Synthesis, College of Materials and Chemistry
& Chemical Engineering, Chengdu University of Technology, Chengdu 610059,
P. R. China
Chiral sulfinamides including t-butanesulfinamide and p-toluenesulfinamide are impor-
tant and versatile reagents that have extensive applications in asymmetric synthesis and
catalysis, and in the synthesis of natural products.1–3 Chiral N-alkylsulfinamides including
N-alkyl t-butanesulfinamides and p-toluenesulfinamides are used as highly enantioselective
organocatalysts and ligands in asymmetric syntheses. In 2006, Sun et al.4 reported that chi-
ral N-(2-hydroxylbenzyl) t-butanesulfinamide displayed excellent asymmetric induction
ability in the reduction of N-arylketimines with trichlorosilane to produce enantiomerically
enriched amines. Khiar et al.5 discovered that monosulfinamides and C2-symmetric bis-
sulfinamides are convenient neutral chiral promoters of the allylation of N-acylhydrazones.
Recently Jacobsen et al.6 developed chiral N-fluoroalkyl t-butanesulfinamides as highly
enantioselective organocatalysts for the enantioselective protonation of enol silanes. Chiral
N-alkyl t-butane- and p-toluenesulfinamides have been used mostly as ligands in asym-
metric catalysis. The use of enantiomerically pure N-phosphino-N-alkyl t-butane- or p-
toluenesulfinamide ligands led to good or excellent enantioselectivities (up to 99%ee) in
the cobalt-catalyzed asymmetric intermolecular Pauson-Khand reaction of norbornadiene7,8
and rhodium(I)-catalyzed [2 + 2 + 2] cycloaddition reactions.9
In 2012, Xu et al.10,11 reported the highly enantioselective rhodium-catalyzed 1,2-
addition of arylboronic acids to α-ketoesters and α-diketones and the asymmetric con-
jugate addition of arylboronic acids to cyclic α,β-unsaturated carbonyl compounds us-
ing a simple chiral N-(sulfinyl)cinnamylamine as ligand. At nearly the same time, Khiar
et al.12 described the rhodium-catalyzed 1,4-addition of boronic acids to both cyclic and
acyclic α,β-unsaturated carbonyl compounds. More recently, Xu et al.13 developed chi-
ral N-(sulfinyl)cinnamylamines as ligands for the rhodium-catalyzed asymmetric ary-
lation of cyclic ketimines, leading to tetrasubstituted carbon stereocenters with high
Received August 5, 2013; in final form December 13, 2013.
Address correspondence to Qingle Zeng, College of Materials and Chemistry & Chemical
Engineering, Chengdu University of Technology, Chengdu 610059, P. R. China. E-mail: qinglezeng
@hotmail.com
164

Selective N-Monoalkylation of Chiral t-Butane- and p-Toluenesulfinamides 165
enantioselectivity. Du et al.14,15 developed enantiomerically pure N-(substituted allyl)
t-butanesulfinamide ligands for the rhodium-catalyzed asymmetric 1,2-addition to α-
diketones and the 1,4-addition to α,β-unsaturated ketones and esters.
Chiral N-alkyl t-butane- and p-toluenesulfinamides have been obtained via the clas-
sical route16–18 first developed by Ellman et al.,19 in the presence of catalysts such as
Ti(OiPr)4 and CuSO4 for example. t-Butanesulfinamide were condensed with aldehydes
or ketones to give the corresponding sulfinylimines,16–18 which were then reduced to the
sulfinamides with sodium borohydride;20,21 similarly, chiral N-sulfinylimidates have been
reduced by sodium borohydride to N-alkyl t-butanesulfinamide.22,23 In addition, nucle-
ophilic substitution of chiral t-butyl t-butanethiosulfinate with primary amines gave N-
alkyled products including N-alkyl sulfinamides.24 Xu et al.11 has used moisture-sensitive
and expensive lithium bis(trimethylsilyl)amide as a base to perform the allylation of chiral
t-butanesulfinamide under an inert atmosphere. As part of our on-going study of the reac-
tions of chiral sulfinamides25 and of our interest in the development of convenient synthetic
methods,26–28 we now report a simple, mild, selective and direct N-monoalkylation of chiral
t-butanesulfinamide and p-toluenesulfinamide with allyl, primary and secondary alkyl and
benzyl halides using potassium hydroxide as the base at room temperature (Scheme 1).
O
O
O
S+
KOH
S+ R'
S+ R'
+
+
R'X
R
N
R'
R
N
H
R
NH2
THF, air, rt
1
2
4 (minor)
3 (major)
Scheme 1
2-Iodobenzyl bromide and t-butanesulfinamide were chosen as model substrates to
optimize the reaction conditions. After examination of bases, solvents, temperature and
ratios of substrates, the optimized conditions were determined. The best yield (85%) of
N-(2-iodobenzyl) t-butanesulfinamide (3a) accompanied by 6% N,N-bis(2-iodobenzyl)
t-butanesulfinamide (4a) was achieved under the following conditions: 1.2 mmol of (R)-
t-butanesulfinamide (1a), 1.0 mmol of 2-iodobenzyl bromide (2a), 1.5 mmol of KOH in
3 mL THF for 4 hours. The monoalkylization of chiral t-butane- and p-toluenesulfinamides
was then evaluated (Table 1). (R)-t-butanesulfinamide was used to react with various alkyl
halides (Table 1, Entries 1–8). Monobenzylation of (R)-t-butanesulfinamide with benzyl
bromide gave nearly the same yield as with 2-iodobenzyl bromide (Entries 1 and 2).
However, benzyl chloride gave poorer yields of both mono- and di-alkylated products
(Entry 3). N-Allyl t-butanesulfinamide, a good chiral ligand in enantioselective rhodium-
catalyzed 1,4-addition to cyclic α,β-unsaturated carbonyl compounds,10,11 was obtained
in good yield (Entry 4). Similarly, chiral ligand N-cinnamyl t-butanesulfinamide, which
is an excellent ligand for 1,4- and 1,2-additions,10,11 may be prepared efficiently by this
protocol (Entry 5); this compound has also been obtained via the typical Ellman two-step
method involving condensation of cinnamaldehyde followed by reduction with sodium
borohydride.16–20 N-Propargyl t-butanesulfinamides was also obtained similarly (Entry 6).
Even less sterically demanding iodomethane and bromoethane successfully and selectively

166
Zeng et al.
Table 1
Monoalkylation of t-Butanesulfinamide and p-Toluenesulfinamidea
Entry
R
RꢀX
Yield (%)
1b
2
3
4c
5c
6
7
8
9
10
11
12
13
14
15
16
17
18d
t-Bu
t-Bu
t-Bu
t-Bu
t-Bu
t-Bu
t-Bu
t-Bu
p-Tol
p-Tol
p-Tol
p-Tol
p-Tol
p-Tol
p-Tol
p-Tol
p-Tol
t-Bu
2-IC6H4CH2Br
BnBr
BnCl
CH2 CHCH2Br
PhCH CHCH2Br
HC≡CCH2Br
CH3I
3a (86), 4a (6)
3b (87), 4b (5)
3b (72), 4b (6)
3c (83), 4c (7)
3d (80), 4d (6)
3e (84), 4e (8)
3f (85), 4f (<5)
3g (87), 4g (<5)
3h (86), 4h (6)
3i (89), 4i (5)
3j (89), 4j (7)
3j (82), 4j (6)
3k (85), 4k (6)
3l (83), 4l (7)
3m (85), 4m (5)
3n (80), 4n (9)
3o (75), 4o (9)
3a (88), 4a (6)
CH3CH2Br
2-IC6H4CH2Br
2-BrC6H4CH2Br
BnBr
BnCl
CH2 CHCH2Br
HC≡CCH2Br
PhCH CHCH2Br
2-Br-5-FC6H3CH2Br
CH3CH2Br
2-IC6H4CH2Br
a) Reaction conditions: 1.0 of mmol (R)-t-butane- or p-toluenesulfinamide, 1.2 mmol of alkyl
halide, 1.5 mmol of KOH, 3 mL THF, at room temperature for 4 hours, unless otherwise noted.
b) Based on chiral HPLC analysis, 100%ee 3a was obtained. c) Except for compounds 3c and 3d,
the other compounds are new. d) 20 mmol of (R)-t-butanesulfinamide, 24 mmol of 2-iodobenzyl
bromide, 30 mmol of KOH and 60 mL THF were used.
led to the corresponding N-monoalkylated t-butanesulfinamides (Entries 7 and 8). All alkyl
halides reacted smoothly with p-toluenesulfinamide to afford good to excellent yields of
N-monoalkylation and a minimal amount of the N,N-dialkylation products (Table 1, Entries
9 to 16 vs. 17). Although the representative procedure was performed on a 1.0 mmol scale,
it has been scaled up to 20 mmol with nearly identified results (Table 1, Entry 18).
The N,N-dialkylated products of tert-butanesulfinamide and p-toluenesulfinamide may
be obtained, provided two equivalents of the alkyl halides and two equivalents of KOH are
used (Scheme 2). The results of symmetric dialkylation are listed in Table 2 (Entry 1–15).
O
O
O
S+
KOH
S+ R'
S+ R'
+
+
2 RX'
R
N
H
R
N
R'
THF, air, rt
R
NH2
3 (minor)
1
2
4 (major)
Scheme 2

Selective N-Monoalkylation of Chiral t-Butane- and p-Toluenesulfinamides 167
Table 2
Symmetric Dialkylation of tert-Butanesulfinamide and p-Toluenesulfinamidea
Entry
R
RꢀX
Yield (%)
1b
2
3
4
5
6
7
8
9
10
11
12
13
14
15
tert-Bu
tert-Bu
tert-Bu
tert-Bu
tert-Bu
tert-Bu
p-Tol
p-Tol
p-Tol
p-Tol
p-Tol
2-IC6H4CH2Br
BnBr
BnCl
CH2 CHCH2Br
PhCH CHCH2Br
HC≡CCH2Br
2-IC6H4CH2Br
2-BrC6H4CH2Br
BnBr
3a (4), 4a (84)
3b (12), 4b (84)
3b (12), 4b (74)
3c (11), 4c (79)
3d (12), 4d (78)
3e (14), 4e (80)
3h (0), 4h (92)
3i (0),4i (94)
3j (0), 4j (91)
3j (0), 4j (88)
3k (0), 4k (91)
3l (0), 4l (92)
BnCl
CH2 CHCH2Br
HC≡CCH2Br
PhCH CHCH2Br
2-Br-5-FC6H3CH2Br
CH3CH2Br
p-Tol
p-Tol
p-Tol
p-Tol
3m (0), 4m (88)
3n (6), 4n (89)
3o (20), 4o (65)
(a) Reaction conditions: 2.2 mmol chiral sulfinamide, 1.0 mmol alkyl halide, 2.5 mmol KOH,
3 mL THF, under air at room temperature for 12 hours. (b) 100%ee 4a were obtained.
Unsymmetrical dialkylated sulfinamides (5) are readily prepared via alkylation of N-
monoalkylated sulfinamides (3) as illustrated by the N-alkylation of (R)-N-(2-iodobenzyl)-
tert-butanesulfinamide (3a) shown in Scheme 3.
O
S
I
O
S
I
KOH
Me3C
N
H
Me3C
N
R
+
R-X
THF, air, rt
3a
R = CH3, 5a, 90%
R = C6H5CH2, 5b, 89%
Scheme 3
In conclusion, a simple, mild and inexpensive KOH-promoted selective N-mono-
and dialkylation of chiral t-butane- and p-toluenesulfinamides without racemization under
ambient conditions has been developed.
Experimental Section
All glassware used were dried in an oven at 120◦C. All chemicals were purchased and used
as received. All compounds were characterized by 1H NMR, 13C NMR, IR spectroscopy and
elemental analysis. NMR spectra were recorded on a Bruker Avance 300 MHz or 400 MHz
instrument. All 1H NMR experiments are reported in δ units, and were measured relative

168
Zeng et al.
to the residual hydrogen signals of CDCl3 (δ 7.26), DMSO-d6 (δ 2.50) or CD3COCD3 (δ
2.05), unless otherwise stated. All 13C NMR experiments are reported in δ units, and were
measured relative to the residual carbon signals of CDCl3 (δ 77.23), DMSO-d6 (δ 39.60)
or CD3COCD3 (δ 206.88, 29.92), unless otherwise stated, and all were obtained with 1H
decoupling. All IR spectra were taken on a Bruker Tensor-27 infrared spectrometer with an
OPUS workstation. Electron-spraying ionization mass spectra were recorded on an Agilent
1200 series LC/MS DVL instrument. Melting points were determined on an Electrothermal
melting point apparatus and are uncorrected. Combustion analyses were performed on a
Euro EA-3000 elemental analyzer (Leeman Labs Inc.). Optical rotation data were measured
on a Rudolph Research Autopol IV Polarimeter (Na D line, cell long 10 cm, λ = 589 nm).
Chiral HPLC analyses were performed on a liquid chromatography (n-hexane / isopropanol
90/10 or 99/1 (v/v), 0.8 mL/min, 25◦C) with a Chiralcel OD-H chiral column (4.6 mm ×
250 mm × 5 μm, Daicel Chemical Industries, Ltd.).
Typical Procedure of N-Monoalkylation of Chiral Sulfinamides
To an oven-dry 25 mL screwed cap tube fitted with a stir bar were added (R)-t-butanesul-
finamide (0.145 g, 1.2 mmol), the alkyl halide (1.0 mmol), potassium hydroxide
(0.084 g, 1.5 mmol) and anhydrous tetrahydrofuran (3 mL). The screwed tube was
sealed with a rubber stopper and the reaction mixture was stirred at room temperature.
After four hours, it was quenched with water (5 mL) and extracted with ethyl acetate
(3 × 20 mL). The combined organic layer was washed with saturated aqueous sodium
chloride, dried over anhydrous sodium sulfate and then filtered. The filtrate was evapo-
rated in vacuo and the resulting crude solid product was purified by silica gel column
chromatography (5:1 petroleum ether and ethyl acetate as eluent) to give (R)-N-alkyl-
t-butanesulfinamide (3a–3o) and a small amount of (R)-N,N-dialkyl-t-butanesulfinamide
(4a–4o).
General Procedure for the Dialkylation of Chiral Sulfinamides
To an oven-dry 25 mL screwed cap tube fitted with a stir bar were added (R)-tert-butane- or
(R)-p-toluenesulfinamide (1.0 mmol), the alkyl halide (2.2 mmol), potassium hydroxide
(0.143 g, 2.5 mmol) and anhydrous tetrahydrofuran (3 mL). The tube was sealed with
a rubber stopper and the reaction mixture was stirred at room temperature. After twelve
hours, it was quenched with water (5 mL) and extracted with ethyl acetate (3 × 20 mL).
The combined organic layers were washed with saturated aqueous sodium chloride, dried
over anhydrous sodium sulfate and then filtered. The filtrate was evaporated in vacuo
and the resulting crude product was purified using silica gel column chromatography
(petroleum ether and ethyl acetate (volume ratio 5:1) as eluent) to give (R)-N,N-bisalkyl
t-butanesulfinamide or p-toluenesulfinamide (4a–4o).
General Procedure for Synthesis of Chiral Unsymmetrical Dialkylated Sulfinamides
To an oven-dry 25 mL screwed cap tube fitted with a stir bar were added (R)-N-(2-
iodobenzyl)-t-butanesulfinamide (3a) (1.0 mmol), alkyl halide (1.2 mmol), potassium

Selective N-Monoalkylation of Chiral t-Butane- and p-Toluenesulfinamides 169
hydroxide (0.073 g, 1.3 mmol) and anhydrous tetrahydrofuran (3 mL). The tube was
sealed with a rubber stopper and the reaction mixture was stirred at room temperature.
After twelve hours, it was quenched with water (5 mL) and extracted with ethyl acetate (3
× 20 mL). The combined organic layers were washed with saturated aqueous sodium chlo-
ride, dried over anhydrous sodium sulfate and then filtered and the filtrate was evaporated
in vacuo. The resulting crude product was purified using silica gel column chromatography
(petroleum ether and ethyl acetate (volume ratio 5:1) as eluent) to give (R)-N-alkyl-N-(2-
iodobenzyl)-t-butanesulfinamide (5a–5b).
(R)-N-(2-Iodobenzyl)-t-butanesulfinamide (Table 1, Entry 1, 3a), white solid
(0.289 g, 86%) with 100%ee (HPLC, Diacel Chiralcel OD-H column, 90:10 hexanes/2-
propanol, 0.8 mL/min, 254 nm; (R)-form, rt = 5.9 min; (S)-form, rt = 9.7 min), mp
112–116◦C, [α]D = −13.269 (c = 0.52, CHCl3). 1H NMR (300 MHz, CDCl3): δ 7.84 (d,
29
J = 7.9 Hz, 1H), 7.42–7.29 (m, 2H), 6.99 (td, J = 7.6, 1.8 Hz, 1H), 4.34 (ddd, J = 21.9,
14.2, 6.5 Hz, 2H), 3.68–3.58 (m, 1H), 1.24 (s, 9H). 13C NMR (75 MHz, CDCl3) δ 140.7,
139.6, 129.7, 129.4, 128.4, 99.3, 56.1, 53.9, 22.6. IR (KBr): 3554, 3415, 3234, 2284, 1642,
1053 cm−1
Anal. Calcd for C11H16INOS: C, 39.18; H, 4.78; N, 4.15. Found: C, 39.33; H, 4.95; N,
4.02.
.
(R)-N,N-bis(2-Iodobenzyl)-t-butanesulfinamide (Table 1, Entry 1, 4a), white solid
(0.033 g, 6%) with 100%ee (HPLC, Diacel Chiralcel OD-H column, 99:1 hexanes/2-
propanol, 0.8 mL/min, 254 nm; (R)-form, rt = 14.4 min; (S)-form, rt = 18.1 min), mp
102–103◦C, [α]D = +26.8 (c = 0.45, CHCl3). 1H NMR (300 MHz, D2O) δ 7.74 (d, J =
29
7.9 Hz, 2H), 7.50 (d, J = 7.7 Hz, 2H), 7.29 (t, J = 7.5 Hz, 2H), 6.95–6.81 (m, 2H), 4.42 (d,
J = 16.2 Hz, 2H), 4.19 (d, J = 16.2 Hz, 2H), 1.17 (s, 9H). 13C NMR (75 MHz, DMSO-d6)
δ 139.5, 138.6, 129.4, 128.9, 128.3, 128.1, 99.7, 58.8, 56.6, 23.1. IR (KBr): 3664, 3475,
3414, 2284, 1612, 1431, 1012 cm−1
Anal. Calcd for C18H21I2NOS: C, 39.08; H, 3.83; N, 2.53. Found: C, 39.29; H, 3.98;
N, 2.41.
.
(R)-N-Benzyl-t-butanesulfinamide (Table 1, Entry 2, 3b), white solid (0.184 g, 87%),
mp 64–66◦C. [α]D = +28.4 (c = 0.51, CHCl3). 1H NMR (300 MHz, CDCl3) δ 7.42–7.25
29
(m, 5H), 4.42–4.31 (m, 1H), 4.26 (dd, J = 13.7, 7.9 Hz, 1H), 3.47 (s, 1H), 1.25 (s, 9H).
13C NMR (75 MHz, CDCl3) δ 129.9, 128.6, 128.6, 128.1, 128.0, 127.7, 127.6, 55.9, 49.4,
49.4, 22.6. IR (KBr): 3708, 3415, 3188, 2305, 1734, 1063 cm−1
.
Anal. Calcd for C11H17NOS: C, 62.52; H, 8.11; N, 6.63. Found: C, 62.35; H, 8.31; N,
6.76.
(R)-N,N-Dibenzyl-t-butanesulfinamide (Table 1, Entry 2, 4b), white solid (0.015 g,
5%), mp 52–55◦C, [α]D = +35.61 (c = 0.44, CHCl3). 1H NMR (300 MHz, CDCl3) δ
12
7.44–7.10 (m, 10H), 4.29 (d, J = 15.4 Hz, 2H), 4.05 (d, J = 15.4 Hz, 2H), 1.22 (s, 9H).13C
NMR (75 MHz, CDCl3) δ 136.6, 128.5, 128.3, 127.2, 58.4, 51.3, 23.1. IR (KBr): 3704,
3475, 3411, 2294, 1612, 1401, 1013 cm−1
.
Anal. Calcd for C18H23NOS: C, 71.72; H, 7.69; N, 4.65. Found: C, 71.52; H, 7.88; N,
4.46.
(R)-N-Allyl-t-butanesulfinamide (Table 1, Entry 4, 3c),10,11 pale yellow liquid
12
1
(0.134 g, 83%), [α]D
= −79.2 (c = 1.33, CHCl3). H NMR (300 MHz, CDCl3) δ
5.82 (ddt, J = 16.1, 10.2, 5.9 Hz, 1H), 5.12 (ddd, J = 13.7, 11.5, 1.4 Hz, 2H), 3.66 (dddd,

170
Zeng et al.
J = 20.6, 14.5, 7.7, 6.7 Hz, 2H), 3.36 (d, J = 5.2 Hz, 1H), 1.14 (s, 9H). 13C NMR (75 MHz,
DMSO-d6) δ 136.6, 115.8, 55.0, 46.9, 22.6. IR (KBr): 3211, 2978, 1644, 1456, 1364,
1048 cm−1
.
Anal. Calcd for C7H15NOS: C, 52.13; H, 9.38; N, 8.69. Found: C, 52.02; H, 9.54;
N, 8.43.
(R)-N,N-Diallyl-t-butanesulfinamide (Table 1, Entry 4, 4c), pale yellow liquid
12
1
(0.014 g, 7%), [α]D
= +35.7 (c = 0.81, CHCl3). H NMR (400 MHz, acetone-d6)
δ 5.76–5.62 (m, 2H), 5.16–4.98 (m, 4H), 3.62 (dd, J = 15.9, 5.1 Hz, 2H), 3.31 (dd, J =
15.9, 6.6 Hz, 2H), 1.00 (s, 9H). 13C NMR (101 MHz, acetone-d6) δ 134.6, 134.5, 117.4,
117.3, 57.2, 49.4, 22.1. IR (KBr): 2977, 1642, 1454, 1361, 1074 cm−1
.
Anal. Calcd for C10H19NOS: C, 59.66; H, 9.51; N, 6.96. Found: C, 59.43; H, 9.72; N,
6.84.
(R)-N-Cinnamyl-t-butanesulfinamide (Table 1, Entry 5, 3d),10,11 white solid
(0.189 g, 80%), mp 55–60◦C, [α]D = −16.7 (c = 0.32, CHCl3). 1H NMR (400 MHz,
12
CDCl3) δ 7.41–7.20 (m, 5H), 6.58 (d, J = 15.8 Hz, 1H), 6.26 (dt, J = 15.8, 6.4 Hz, 1H),
4.01–3.91 (m, 1H), 3.91–3.81 (m, 1H), 3.37 (s, 1H), 1.25 (d, J = 4.8 Hz, 9H). 13C NMR
(101 MHz, CDCl3) δ 136.4, 132.5, 128.5, 127.8, 126.4, 55.7, 47.8, 22.6. IR (KBr): 3699,
3555, 3414, 2923, 2285, 1617, 1052 cm−1
Anal. Calcd for C13H19NOS: C, 65.78; H, 8.07; N, 5.90. Found: C, 65.93; H, 8.27; N,
5.65.
(R)-N,N-Dicinnamyl-t-butanesulfinamide (Table 1, Entry 5, 4d), white solid
.
(0.021 g, 6%), mp 50–54◦C, [α]D = +26.4 (c = 0.60, CHCl3). H NMR (400 MHz,
DMSO-d6) δ 7.40 (d, J = 7.5 Hz, 4H), 7.30 (t, J = 7.5 Hz, 4H), 7.22 (t, J = 7.2 Hz, 2H),
6.54 (d, J = 15.9 Hz, 2H), 6.25 (dt, J = 15.8, 6.4 Hz, 2H), 3.84 (dd, J = 15.8, 5.9 Hz,
2H), 3.65–3.56 (m, 2H), 1.11 (s, 9H). 13C NMR (101 MHz, DMSO-d6) δ 136.7, 133.0,
129.0, 128.0, 126.7, 126.3, 57.8, 49.5, 23.0. IR (KBr): 3699, 3555, 3414, 2923, 2285, 1617,
12
1
1052 cm−1
Anal. Calcd for C22H27NOS: C, 74.74; H, 7.70; N, 3.96. Found: C, 74.54; H, 7.92; N,
3.89.
(R)-N-(Prop-2-ynyl)-t-butanesulfinamide (Table 1, Entry 6, 3e), colorless liquid
.
12
1
(0.133 g, 84%), [α]D = −19.4 (c = 0.46, CHCl3). H NMR (400 MHz, acetone-d6) δ
4.69 (s, 1H), 3.72 (ddd, J = 5.6, 3.9, 2.6 Hz, 2H), 2.65 (t, J = 2.5 Hz, 1H), 1.06 (s, 10H).
13C NMR (101 MHz, acetone-d6) δ 81.0, 72.5, 72.4, 55.1, 33.3, 33.1, 21.9. IR (KBr): 2918,
1642, 1488, 1415, 1334, 1066 cm−1
Anal. Calcd for C7H13NOS: C, 52.79; H, 8.23; N, 8.80. Found: C, 52.56; H, 8.43; N,
8.67.
.
(R)-N,N-Di(prop-2-ynyl)-t-butanesulfinamide (Table 1, Entry 6, 4e), pale yellow
liquid (0.016 g, 8%), [α]D = +123.7 (c = 1.80, CHCl3). 1H NMR (400 MHz, acetone-
12
d6) δ 3.87 (dd, J = 18.2, 1.7 Hz, 2H), 3.63 (d, J = 18.2 Hz, 2H), 2.74 (dd, J = 3.1, 1.6 Hz,
2H), 1.04 (d, J = 1.5 Hz, 10H). 13C NMR (101 MHz, acetone-d6) δ 78.2, 73.7, 73.7, 58.0,
35.7, 21.6. IR (KBr): 2947, 1652, 1404, 1261, 1045 cm−1
.
Anal. Calcd for C10H15NOS: C, 60.88; H, 7.66; N, 7.10. Found: C, 60.67; H, 7.76; N,
7.30.
(R)-N-Methyl-t-butanesulfinamide (Table 1, Entry 7, 3f), colorless liquid (0.115 g,
12
1
85%), [α]D = −49.2 (c = 0.73, CHCl3). H NMR (300 MHz, CDCl3) δ 3.17 (s, 1H),

Selective N-Monoalkylation of Chiral t-Butane- and p-Toluenesulfinamides 171
2.80 (d, J = 5.4 Hz, 3H), 1.17 (s, 9H). 13C NMR (75 MHz, DMSO-d6) δ 54.9, 30.5, 22.6.
IR (KBr): 2998, 2017, 1642, 1617, 1341, 1051 cm−1
.
Anal. Calcd for C5H13NOS: C, 44.41; H, 9.69; N, 10.36. Found: C, 44.31; H, 9.90; N,
10.54.
(R)-N-Ethyl-t-butanesulfinamide (Table 1, Entry 8, 3g), pale yellow liquid (0.130 g,
7%), [α]D = −69.2 (c = 0.65, CHCl3). 1H NMR (400 MHz, CDCl3) δ 3.48 (s, 1H),
12
3.32–3.20 (m, 1H), 3.18–3.08 (m, 1H), 1.26–1.17 (m, 12H). 13C NMR (101 MHz, CDCl3)
δ 55.1, 40.2, 22.4, 16.3. IR (KBr): 3012, 2187, 1642, 1617, 1346, 1087 cm−1
.
Anal. Calcd for C6H15NOS: C, 48.28; H, 10.13; N, 9.38. Found: C, 48.38; H, 10.23;
N, 9.15.
(R)-N-(2-Iodobenzyl)-p-toluenesulfinamide (Table 1, Entry 9, 3h), white solid
(0.319 g, 86%), mp 105–109◦C, [α]D = −46.7(c = 0.71, CHCl3). 1H NMR (300 MHz,
12
CDCl3) δ 7.79 (dd, J = 7.9, 0.8 Hz, 1H), 7.63 (d, J = 8.2 Hz, 2H), 7.33–7.22 (m, 4H), 6.94
(td, J = 7.8, 2.1 Hz, 1H), 4.51 (t, J = 6.3 Hz, 1H), 4.29 (dd, J = 14.0, 5.9 Hz, 1H), 4.03
(dd, J = 14.0, 6.9 Hz, 1H), 2.40 (s, 3H). IR (KBr): 3710, 3555, 3421, 2920, 2283, 1617,
1046 cm−1
.
Anal. Calcd for C14H14INOS: C, 45.29; H, 3.80; N, 3.77. Found: C, 45.49; H, 3.96; N,
3.58.
(R)-N,N-bis(2-Iodobenzyl)-p-toluenesulfinamide (Table 1, Entry 9, 4h), white solid
(0.035 g, 6%), mp 85–88◦C, [α]D = +26.3 (c = 0.23, CHCl3). H NMR (300 MHz,
CDCl3) δ 7.69 (dd, J = 10.8, 4.2 Hz, 4H), 7.33–7.19 (m, 6H), 6.84 (td, J = 7.7, 1.7 Hz,
2H), 4.25 (q, J = 15.0 Hz, 4H), 2.34 (s, 3H); 13C NMR (151 MHz, DMSO-d6) δ 141.8,
140.6, 139.5, 138.5, 130.5, 130.2, 130.0, 129.8, 128.7, 128.6, 126.0, 100.5, 56.5, 21.3. IR
12
1
(KBr): 3704, 3555, 3414, 2918, 2285,1617,1431,1010 cm−1
Anal. Calcd for C21H19I2NOS: C, 42.95; H, 3.26; N, 2.39. Found: C, 42.79; H, 3.49;
N, 2.24.
(R)-N-(2-Bromobenzyl)-p-toluenesulfinamide (Table 1, Entry 10, 3i), white solid
.
(0.287 g, 89%), mp 93–95◦C, [α]D = −32.7 (c = 0.60, CHCl3). H NMR (300 MHz,
CDCl3) δ 7.62 (d, J = 8.2 Hz, 2H), 7.51 (d, J = 7.8 Hz, 1H), 7.35–7.18 (m, 4H), 7.11 (ddd,
J = 8.7, 7.8, 4.2 Hz, 1H), 4.57 (t, J = 6.3 Hz, 1H), 4.33 (dd, J = 14.1, 5.8 Hz, 1H), 4.05
(dd, J = 14.1, 7.1 Hz, 1H), 2.40 (s, 3H). 13C NMR (151 MHz, DMSO-d6) δ 141.6, 141.1,
138.0, 132.7, 130.5, 129.9, 129.5, 128.1, 126.2, 123.1, 43.6, 21.2. IR (KBr): 3193, 3057,
12
1
2920, 1596, 1569, 1441, 1059 cm−1
Anal. Calcd for C14H14BrNOS: C, 51.86; H, 4.35; N, 4.32. Found: C, 51.76; H, 4.54;
N, 4.28.
.
(R)-N,N-bis(2-Bromobenzyl)-p-toluenesulfinamide (Table 1, Entry 10, 4i), white
solid (0.025 g, 5%), mp 81–83◦C, [α]D = +22.7(c = 0.24, CHCl3). 1H NMR (300 MHz,
12
D2O) δ 7.64 (d, J = 8.2 Hz, 2H), 7.41 (dd, J = 7.9, 1.0 Hz, 2H), 7.34–7.08 (m, 7H), 7.01
(td, J = 7.7, 1.7 Hz, 2H), 4.36 (d, J = 15.0 Hz, 2H), 4.23 (d, J = 15.0 Hz, 2H), 2.33 (s,
3H). 13C NMR (151 MHz, DMSO-d6) δ 140.6, 135.7, 132.9, 131.2, 130.1, 130.2, 129.8,
128.6, 127.9, 126.0, 123.9, 51.8, 21.3. IR (KBr): 3669, 3435, 3214, 2918, 2285,1617,1432,
1021 cm−1
Anal. Calcd for C21H19Br2NOS: C, 51.13; H, 3.88; N, 2.84. Found: C, 51.33; H, 3.94;
N, 2.73.
.

172
Zeng et al.
(R)-N-Benzyl-p-toluenesulfinamide (Table 1, Entry 11, 3j), white solid (0.218 g,
89%), mp 73–75◦C, [α]D = −33.3 (c = 0.15, CHCl3). 1H NMR (300 MHz, CDCl3) δ
7.64 (d, J = 8.2 Hz, 2H), 7.40–7.17 (m, 7H), 4.50–4.37 (m, 1H), 4.22 (dd, J = 13.5, 5.1 Hz,
1H), 3.88 (dd, J = 13.5, 7.2 Hz, 1H), 2.41 (s, 3H).13C NMR (75 MHz, CDCl3) δ 141.2,
140.7, 137.7, 129.5, 128.5, 128.2, 127.5, 125.9, 44.4, 21.2. IR (KBr): 3698, 3555, 3414,
12
2920, 2283, 1617, 1057 cm−1
Anal. Calcd for C14H15NOS: C, 68.54; H, 6.16; N, 5.71. Found: C, 68.26; H, 6.48; N,
5.93.
.
(R)-N,N-Dibenzyl-p-toluenesulfinamide (Table 1, Entry 11, 4j), white liquid
12
1
(0.023 g, 7%), [α]D
= +21.4 (c = 0.35, CHCl3). H NMR (400 MHz, CDCl3) δ
7.63 (d, J = 8.2 Hz, 2H), 7.29 (dd, J = 11.2, 4.6 Hz, 6H), 7.22–7.11 (m, 4H), 4.14–4.03
(m, 4H), 2.37 (s, 3H).13C NMR (101 MHz, CDCl3) δ 141.4, 141.0, 136.6, 129.6, 129.0,
128.6, 128.5, 127.6, 126.2, 51.2, 21.4, 21.4. IR (KBr): 3708, 3535, 3414, 2904, 2283, 1617,
1022 cm−1
Anal. Calcd for C21H21NOS: C, 75.19; H, 6.31; N, 4.18. Found: C, 75.29; H, 6.52; N,
4.36.
.
(R)-N-Allyl-p-toluenesulfinamide (Table 1, Entry 13, 3k), colorless liquid (0.166 g,
85%), [α]D = −14.9 (c = 0.23, CHCl3). 1H NMR (600 MHz, DMSO-d6) δ 7.48 (d, J =
12
8.1 Hz, 2H), 7.33 (d, J = 8.0 Hz, 2H), 6.70 (t, J = 5.7 Hz, 1H), 5.71 (ddd, J = 16.0, 10.8,
5.6 Hz, 1H), 5.12 (dd, J = 17.2, 1.6 Hz, 1H), 5.00 (dd, J = 10.3, 1.4 Hz, 1H), 3.44–3.38
(m, 2H), 2.34 (s, 3H). 13C NMR (151 MHz, DMSO-d6) δ 141.9, 140.8, 136.1, 129.8, 126.2,
116.5, 42.2, 21.2. IR (KBr): 3654, 3460, 3336, 2821, 1618, 1034 cm−1
Anal. Calcd for C10H13NOS: C, 61.50; H, 6.71; N, 7.17. Found: C, 61.46; H, 6.92; N,
7.32.
(R)-N,N-Diallyl-p-toluenesulfinamide (Table 1, Entry 13, 4k), colorless liquid
.
12
1
(0.014 g, 6%), [α]D = +18.7 (c = 2.0, CHCl3). H NMR (400 MHz, acetone-d6) δ
7.44 (d, J = 8.2 Hz, 2H), 7.28–7.22 (m, 2H), 5.70–5.57 (m, 2H), 5.02 (ddd, J = 13.7, 11.4,
1.3 Hz, 4H), 3.47 (qd, J = 15.2, 6.4 Hz, 4H), 2.27 (s, 3H). 13C NMR (101 MHz, acetone-d6)
δ 141.9, 141.1, 134.6, 134.5, 129.4, 126.0, 117.7, 117.72, 49.8, 49.7, 49.7, 20.4, 20.3. IR
(KBr): 3575, 3479, 3414, 3356, 2901, 1608, 1022 cm−1
Anal. Calcd for C13H17NOS: C, 66.34; H, 7.28; N, 5.95. Found: C, 66.65; H, 7.39; N,
5.82.
.
(R)-4-Methyl-N-(prop-2-ynyl)benzenesulfinamide (Table 1, Entry 14, 3l), pale yel-
low liquid (0.160 g, 83%), [α]D = −20.9 (c = 0.81, CHCl3). 1H NMR (400 MHz, CDCl3)
12
δ 7.60 (d, J = 8.2 Hz, 2H), 7.32 (d, J = 8.0 Hz, 2H), 4.41–4.33 (m, 1H), 3.86 (ddd, J =
16.8, 4.8, 2.6 Hz, 1H), 3.49 (ddd, J = 16.8, 7.1, 2.6 Hz, 1H), 2.42 (s, 3H), 2.28 (t, J =
2.6 Hz, 1H). 13C NMR (101 MHz, CDCl3) δ 141.6, 139.9, 129.7, 125.9, 79.6, 72.8, 72.7,
29.7, 21.4, 21.4. IR (KBr): 3315, 2206, 1632, 1461, 1313, 1012 cm−1
Anal. Calcd for C10H11NOS: C, 62.15; H, 5.74; N, 7.25. Found: C, 62.32; H, 5.96; N,
7.17.
(R)-4-Methyl-N,N-di(prop-2-ynyl)benzenesulfinamide (Table 1, Entry 14, 4l), pale
.
12
1
yellow liquid (0.016 g, 7%), [α]D = +17.3 (c = 0.80, CHCl3). H NMR (400 MHz,
acetone-d6) δ 7.42 (d, J = 8.2 Hz, 2H), 7.27 (d, J = 7.9 Hz, 2H), 3.80 (dd, J = 6.4, 2.3 Hz,
4H), 2.74 (t, J = 2.1 Hz, 2H), 2.28 (s, 3H). 13C NMR (101 MHz, CDCl3) δ 141.8, 139.8,

Selective N-Monoalkylation of Chiral t-Butane- and p-Toluenesulfinamides 173
129.7, 129.3, 126.1, 77.9, 74.1, 74.1, 36.6, 36.5, 36.4, 21.4, 21.3. IR (KBr): 3217, 2126,
1616, 1492, 1421, 1339, 1063 cm−1
.
Anal. Calcd for C13H13NOS: C, 67.50; H, 5.66; N, 6.06. Found: C, 67.22; H, 5.93; N,
6.23.
(R)-N-Cinnamyl-p-toluenesulfinamide (Table 1, Entry 15, 3m), light pink solid
(0.230 g, 85%), mp 90–92◦C, [α]D = −23.4 (c = 0.35, CHCl3). 1H NMR (400 MHz,
12
CDCl3) δ 7.62 (d, J = 8.2 Hz, 2H), 7.35–7.19 (m, 7H), 6.48 (d, J = 15.8 Hz, 1H), 6.17
(dt, J = 15.8, 6.5 Hz, 1H), 4.30 (s, 1H), 3.88–3.79 (m, 1H), 3.62–3.54 (m, 1H), 2.40 (s,
3H). 13C NMR (101 MHz, CDCl3) δ 141.3, 140.8, 136.4, 132.7, 129.6, 128.5, 127.7, 126.4,
125.9, 43.2, 29.7. IR (KBr): 3555, 3479, 3414, 2821, 1618, 1062 cm−1
Anal. Calcd for C16H17NOS: C, 70.81; H, 6.31; N, 5.16. Found: C, 70.63; H, 6.51; N,
5.02.
.
(R)-N,N-Dicinnamyl-p-toluenesulfinamide (Table 1, Entry 15, 4m), pale yellow
solid (0.019 g, 5%), mp 80–85◦C, [α]D = +33.2 (c = 0.24, CHCl3). 1H NMR (400 MHz,
12
CDCl3) δ 7.53 (d, J = 8.2 Hz, 2H), 7.30–7.18 (m, 10H), 7.19–7.10 (m, 2H), 6.36
(d, J = 15.9 Hz, 2H), 6.04 (dt, J = 15.8, 6.8 Hz, 2H), 3.84–3.67 (m, 4H), 2.31 (s,
3H). 13C NMR (101 MHz, DMSO-d6) δ 136.7, 133.0, 129.0, 128.1, 126.7, 126.3, 57.8,
49.5, 23.0. IR (KBr): 3705, 3479, 3414, 2920, 1617, 1438, 1022 cm−1
Anal. Calcd for C25H25NOS: C, 77.48; H, 6.50; N, 3.61. Found: C, 77.28; H, 6.82; N,
3.36.
(R)-N-(2-Bromo-5-fluorobenzyl)-p-toluenesulfinamide (Table 1, Entry 16, 3n),
.
white solid (0.273 g, 80%), mp 105–109◦C, [α]D = −17.2 (c = 0.34, CHCl3). H
NMR (400 MHz, CDCl3): δ = 2.42 (s, 3 H), 4.06 (J = 14.9, 7.1 Hz, 1 H), 4.29 (d, J =
14.9, 6.0 Hz, 1 H), 4.69 (bs, 1 H,), 6.86 (ddd, J = 8.8, 7.8, 3.0 Hz, 1 H), 6.97 (dd, J =
9.1, 3.0 Hz, 1 H), 7.31 (d, J = 8.1 Hz, 2 H), 7.46 (dd, J = 8.8, 5.3 Hz, 1 H), 7.62
(d, J = 8.1 Hz, 2 H,). 13C NMR (100 MHz, CDCl3): δ = 21.5, 44.9, 116.3, 117.6, 117.8,
126.1, 129.7, 134.0, 139.7, 140.6, 141.8, 162.0. IR (KBr): 3645, 3479, 3314, 2920, 1647,
12
1
1418, 1023 cm−1
Anal. Calcd for C14H13BrFNOS: C, 49.13; H, 3.83; N, 4.09. Found: C, 49.35; H, 3.67;
N, 4.23.
(R)-N,N-bis(2-Bromo-5-fluorobenzyl)-p-toluenesulfinamide (Table 1, Entry 16,
.
4n), white solid (0.048 g, 9%), mp 92–95◦C, [α]D = +9.2 (c = 0.64, CHCl3). H
NMR (300 MHz, CHCl3) δ 7.66 (d, J = 8.2 Hz, 2H), 7.44–7.23 (m, 4H), 7.00 (dd, J = 9.3,
3.0 Hz, 2H), 6.77 (td, J = 8.3, 3.1 Hz, 2H), 4.29 (q, J = 15.3 Hz, 4H), 2.37 (s, 3H). 13C
NMR (100 MHz, CDCl3): δ = 24.5, 48.9, 116.3, 117.6, 117.8, 126.1, 129.7, 134.5, 139.7,
12
1
140.6, 141.7, 163.2. IR (KBr): 3635, 3479, 3416, 2931, 1620, 1431, 1022 cm−1
.
Anal. Calcd for C21H17Br2F2NOS: C, 47.66; H, 3.24; N, 2.65. Found: C, 47.83; H,
3.50; N, 2.42.
(R)-N-Ethyl-p-toluenesulfinamide (Table 1, Entry 17, 3o), pale yellow solid (0.137 g,
75%), mp 65–70◦C, [α]D = −29.2 (c = 3.80, CHCl3). 1H NMR (400 MHz, CDCl3) δ
12
7.59 (d, J = 8.2 Hz, 2H), 7.32–7.28 (m, 2H), 4.10 (t, J = 5.3 Hz, 1H), 3.22–3.10 (m, 1H),
2.92–2.81 (m, 1H), 2.41 (s, 3H), 1.15 (t, J = 7.2 Hz, 3H). 13C NMR (101 MHz, CDCl3) δ
141.0, 140.8, 129.4, 126.2, 41.8, 21.3, 21.3, 14.4. IR (KBr): 3553, 3415, 3194, 2980, 2287,
1632, 1455, 1117 cm−1
.

174
Zeng et al.
Anal. Calcd for C9H13NOS: C, 58.98; H, 7.15; N, 7.64. Found: C, 58.76; H, 7.45; N,
7.37.
(R)-N,N-Diethyl-p-toluenesulfinamide (Table 1, Entry 17, 4o), pale yellow liquid
(0.020 g, 9%), [α]D = +21.3 (c = 0.65, CHCl3). 1H NMR (400 MHz, CDCl3) δ 7.54 (d,
12
J = 8.1 Hz, 2H), 7.33–7.26 (m, 2H), 3.13 (q, J = 7.4 Hz, 4H), 2.41 (s, 3H), 1.12 (t, J =
7.2 Hz, 6H). 13C NMR (101 MHz, CDCl3) δ 141.0, 140.8, 129.4, 126.2, 41.8, 21.3, 21.3,
14.4. IR (KBr): 3693, 3415, 3214, 2880, 2287, 1632, 1325, 1017 cm−1
.
Anal. Calcd for C11H17NOS: C, 62.52; H, 8.11; N, 6.63. Found: C, 62.26; H, 8.36; N,
6.48.
(R)-N-(2-Iodobenzyl)-N-methyl-t-butanesulfinamide (5a), colorless oil (0.309 g,
17
1
90%), [α]D = +31.5 (c = 0.51, CHCl3). H NMR (300 MHz, CDCl3) δ 7.78 (d, J =
7.8 Hz, 1H), 7.42–7.23 (m, 2H), 6.92 (td, J = 7.7, 1.7 Hz, 1H), 4.20 (q, J = 15.8 Hz, 2H),
2.63 (s, 3H), 1.15 (s, 9H). 13C NMR (75 MHz, CDCl3) δ 139.47 (s), 139.01 (s), 128.91 (d,
J = 3.9 Hz), 128.23 (s), 99.24 (s), 61.34 (s), 58.53 (s), 29.50 (s), 23.30 (s).
Anal. Calcd for C12H18INOS: C, 41.03; H, 5.17; N, 3.99. Found: C, 41.25; H, 5.31; N,
3.76.
(R)-N-(2-Iodobenzyl)-N-benzyl-t-butanesulfinamide (5b), colorless oil (0.381 g,
= +28.5 (c = 0.36, CHCl3). 1H NMR (300 MHz, CDCl3) δ 7.78
17
89%), [α]D
(d, J = 7.2 Hz, 1H), 7.49 (d, J = 6.9 Hz, 1H), 7.39–7.21 (m, 6H), 6.93 (dd, J = 10.8,
4.3 Hz, 1H), 4.33 (dd, J = 15.7, 4.1 Hz, 2H), 4.13 (dd, J = 39.7, 15.7 Hz, 2H), 1.17 (s, 9H).
13C NMR (75 MHz, CDCl3) δ 139.56 (s), 138.94 (s), 136.36 (s), 129.36 (d, J = 19.8 Hz),
128.87 (d, J = 8.9 Hz), 128.59–127.94 (m), 127.48 (s), 99.51 (s), 58.58 (s), 55.95 (s), 52.40
(s), 23.12 (s).
Anal. Calcd for C18H22INOS: C, 50.59; H, 5.19; N, 3.28. Found: C, 50.77; H, 5.34; N,
3.48.
Acknowledgments
We sincerely thank the Executive Editor of the Journal, Prof. J.-P. Anselme (University of
Massachusetts Boston), for his careful revision of this paper. We appreciate the National
Natural Science Foundation of China (No. 21372034), the Science and Technology Bureau
of Sichuan (No. 2011HH0016), the Incubation Program for Excellent Innovation Team of
Chengdu University of Technology and the Opening Fund of State Key Laboratory of Geo-
hazard Prevention and Geoenvironment Protection (No. SKLGP2012K005) for financial
support.
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