The synthesis of N-TBS-S-alkynyl sulfoximines

Article abstract of DOI:10.1055/s-2008-1077956

Treatment of β-keto sulfoximines with triflic anhydride and Hu?nig's base in toluene resulted in the formation of S-alkynyl sulfoximines in good yield.

Full text of DOI:10.1055/s-2008-1077956

LETTER
2051
The Synthesis of N-TBS–S-Alkynyl Sulfoximines
S
-Alkynyl Sulfoximine
i
s
chael Harmata,* Chaofeng Huang, Yugang Chen, Pinguan Zheng, Xuefeng Gao, Weijiang Ying
Department of Chemistry, University of Missouri-Columbia, Columbia, MO 65211, USA
Fax +1(573)8822754; E-mail: harmatam@missouri.edu
Received 18 April 2008
have been reported in the literature.8 We undertook our
studies mindful of this situation, the potentially very rich
chemistry of S-alkynyl sulfoximines and their relationship
to the as yet unknown S-allenyl and S-propargyl sulfox-
imines.
Abstract: Treatment of b-keto sulfoximines with triflic anhydride
and Hünig’s base in toluene resulted in the formation of S-alkynyl
sulfoximines in good yield.
Key words: sulfoximine, alkyne, triflic anhydride, Hünig’s base
Actually, over 20 years ago we attempted to prepare an S-
alkynyl sulfoximine via the reaction of sulfonimidoyl
chloride 4 with 1-trimethylsilylpropyne in the presence of
a Lewis acid.9 Instead of obtaining 7, in analogy to chem-
istry involving sulfonyl chlorides,10 the 2,1-benzothiazine
8 was produced and this reaction became the focus of
some studies in our group (Scheme 1).11
The sulfoximine functional group is one of established
and growing significance in organic chemistry.1 By virtue
of the fact that it can be easily rendered enantiomerically
pure and is relatively robust, this group has found great
utility in the design and development of chiral ligands2
and chiral scaffolds,3 with important implications for or-
ganic synthesis.
O
O
Given the impact this functional group has had it is inter-
esting to note that its combination with other functional
groups is not as common as might be expected. While S-
alkynyl sulfones are common and easily accesible,4 S-
alkynyl sulfoximines are much more rare and can justifi-
ably be characterized as an emerging functional group
whose chemistry remains to be completely explored.
Lewis acid
p-Tol
S
N
Cl
CTMS CMe
p-Tol
S
N
Ph
4
Ph
5
Me
+
O
TMS
O
p-Tol
S
N
C
CMe
TMS
X
S
N
Two approaches have been reported for the synthesis of S-
alkynyl sulfoximines. Craig reported that dehydration of
an N-tosyl and N-triflyl b-keto sulfoximine resulted in the
formation of the corresponding S-alkynyl sulfoximines in
44–77% yields.5 It is essentially this procedure that we
used in the generation of our sulfoximines.
Ph
p-Tol
7
6
Me
75%
O
S
N
p-Tol
8
More recently, Malacria and co-workers have demonstrat-
ed that the imination of acetylenic sulfoxides is possible.6
Thus, treatment of 1 with iminoiodinane 2 in the presence
of a catalytic amount of copper triflate afforded 3 in 89%
yield with complete retention of configuration at sulfur
(Equation 1). Marek and Bolm used this chemistry to syn-
thesize S-alkynyl sulfoximines as precursors for the syn-
thesis of stereochemically defined vinyl sulfoximines.7
Scheme 1
More recently, we simply wanted to produce a selection of
S-alkynyl sulfoximines to get first hand spectroscopic and
stability data in anticipation of more in-depth studies in-
volving the alkynyl/allenyl/propargyl family of S-substi-
tuted sulfoximines.12
We first synthesized b-keto sulfoximines using the meth-
od of Cinquini and co-workers.13 Sulfoximine 9 was pre-
pared by known methods.14 Subsequently, deprotonation
of 9 with LDA followed by reaction with a methyl ester
afforded the b-keto sulfoximines 10 in good to excellent
yields (Table 1).
O
O
PhINTs (2)
NTs
BuC
C
S
BuC
C
S
2+
Cu(OTf)2 (10 mol%)
MeCN, r.t.
p-Tol
p-Tol
1
3
89%
Equation 1
To prepare N-TBS–S-alkynyl sulfoximines, the b-keto
In spite of these seminal contributions, it appears that only sulfoximines were treated with three equivalents of diiso-
seven constitutionally unique S-alkynyl sulfoximines propylethylamine (DIPEA, Hünig’s base) and the solution
was then refluxed to effect elimination and produce the
triple bond (procedure A). In other cases, preparing and
isolating the enol triflate before elimination proved ad-
vantageous (procedure B). The yields of the correspond-
SYNLETT 2008, No. 13, pp 2051–2055
Advanced online publication: 15.07.2008
DOI: 10.1055/s-2008-1077956; Art ID: S03408ST
x
x
.x
x
.2
0
0
8
© Georg Thieme Verlag Stuttgart · New York

2052
M. Harmata et al.
LETTER
Table 1 Synthesis of b-Keto Sulfoximines
all conditions examined thus far have resulted in decom-
position of the starting material.15
NTBS
O
O
LDA, THF
RCO2Me
TBSN
Ph
Ph
S
Me
Interestingly, using the same approach for the synthesis of
N-benzyl–S-alkynyl sulfoximines has thus far failed.
S
R
O
9
10
O
OTf
O
O
Entry
R
Product
10a
10b
10c
Yield (%)
BnN
Ph
Tf2O
py
BnN
Ph
S
S
i-Pr
i-Pr
1
2
Ph
92
89
85
83
95
75
71
75
75
72
12
13
H
2-ClC6H4
Me
O
HN
Ph
DIPEA, toluene
reflux, 2 h, 55%
S
i-Pr
3
14
4
cyclohexyl
i-Pr
10d
10e
Scheme 2
5
While the preparation of the appropriate b-keto sulfox-
imines was straightforward, attempts to make the corre-
sponding enol triflates or directly convert them into S-
alkynyl sulfoximines often produced complex reactions
mixtures under the same conditions that produced clean
products for 10. However, when 12 was treated with Tf2O
and Hünig’s base in toluene at room temperature, an ap-
proximately 36% yield of 13 was isolated in reasonable
purity as assessed by 1H NMR (Scheme 2). When this ma-
terial was treated with Hunig’s base in refluxing toluene,
the debenzylated N-H alkenyl sulfoximine 14 was isolated
in 55% yield. This internal redox process is another inter-
esting aspect of sulfoximine chemistry that we are now
exploring.
6
4-pentenyl
Et
10f
7
10g
10h
10i
8
1-styryl
cyclohexylmethyl
furyl
9
10
10j
11
10k
97
ing alkynes ranged from good to excellent. The results are
summarized in Table 2.
In an attempt to begin to learn more about these alkynes,
attempts were made to remove the silyl group. However,
Ts
Ts
p-Tol
N
S
N
BnN3 (1.5 equiv)
H2O, 3 h, 31%
S
N
Bu
p-Tol
Bu
O
O
Table 2 Synthesis of S-Alkynyl Sulfoximines
N
3
15
Bn
N
NTBS
S
O
O
TBSN
Ph
Tf2O
py
Ph
R
S
Equation 2
R
O
11
10
Finally, Bolm has recently reported the reaction of azide
with 3 (Equation 2).16 Our preliminary studies also sug-
gest that related ‘click’ chemistry17 with S-alkynyl sulfox-
imine is possible, but that elucidation of the structural and
experimental features of the reaction that control selectiv-
ity will need to be accomplished. Thus, treatment of 11b
with PhN3 (1.5 equiv) in water at reflux for 18 hours re-
sulted in the formation of 16a and 16b as a 1:1 mixture of
regioisomers in 72% yield. Some evidence for a steric in-
fluence in the control of regiochemistry was found upon
the reaction of 11e. This produced 17a and 17b as a 4:1
mixture of regioisomers in 84% yield (Scheme 3). The re-
giochemistry was established using NOESY spectrosco-
py.
Entry
Educt
10a
10b
10c
10d
10e
10f
R
Product
11aa
11ba
11ca
11da
11ea
11fa
Yield (%)
1
2
Ph
68
94
61
62
53
54
47
0
2-ClC6H4
Me
3
4
cyclohexyl
i-Pr
5
6
4-pentenyl
Et
7
10g
10h
10i
11ga
11ha
11ia
8
1-styryl
9
cyclohexylmethyl
furyl
62
78
In summary, we have reported a synthesis of N-TBS–S-
alkynyl sulfoximines that is simple and experimentally
convenient.18 More intriguing is the nature of these and re-
lated sulfoximines. Their chemistry and reactivity re-
mained largely unexplored. Future studies will focus
generating and studying members and relative of the al-
kynyl sulfoximine family.19
10
10j
11jb
11
10k
11kb
73
a Prepared according to procedure A.
b Prepared according to procedure B.
Synlett 2008, No. 13, 2051–2055 © Thieme Stuttgart · New York

LETTER
S-Alkynyl Sulfoximines
2053
Cl
(15) Conditions tried included: (a) 0 °C, 1 h, 0.1 M TBAF (2.0
equiv) in THF; (b) 0 °C, 1 h, 0.1 M TBAF–AcOH (1.2
equiv) in THF; (c) –78 °C → 0 °C, 1 h, 0.1 M HF–pyridine
(1.2 equiv) in THF; (d) 23 °C, 2 h, 0.05 M n-Bu4NSiF2Ph3
(2.0 equiv) in THF.
(16) Füger, B.; Sklute, G.; Marek, I.; Bolm, G. Y.; Bolm, C.
Synlett 2008, 116.
O
PhN3, H2O
Ph
S
reflux, 18 h
72%
NTBS
11b
Ph
N
N
N
N
O
O
(17) Kolb, H. C.; Finn, M. G.; Sharpless, K. B. Angew. Chem. Int.
Ed. 2001, 40, 2004.
N
N
S
S
Ph
Cl
Ph
Ph
NTBS
NTBS
(18) General Experimental Procedures: To a solution of
DIPEA (2.5 mmol) in THF (10 mL) at 0 °C, was added BuLi
(2.5 mmol) with stirring. After 10 min, the solution was
cooled to –78 °C, and slowly added to a flask that contained
9 (2 mmol) in THF (10 mL) at –78 °C. The solution was
warmed to r.t. for 15 min, then was cooled back to –78 °C.
Ester was added (10 mmol) and the solution was warmed to
r.t. and then refluxed for 8 h. After TLC showed no starting
material, the solution was quenched by sat. NH4Cl (10 mL),
and extracted with Et2O (3 × 10 mL). The combined organic
phases were washed with brine (10 mL), and dried with
Na2SO4. Removal of solvent and chromatographic
Cl
+
1:1
16a
16b
O
PhN3, H2O
Ph
S
reflux, 18 h
84%
NTBS
11e
Ph
N
N
N
N
O
O
N
N
S
Ph
+
S
Ph
Ph
purification afforded keto sulfoximines 10.
NTBS
NTBS
Procedure A: To 10 (1 mmol) in toluene (5 mL) at r.t. was
slowly added DIPEA (6.0 equiv), followed by triflate
anhydride (2.3 equiv). The solution was refluxed until TLC
showed no starting material remained. It was quenched by
sat. NH4Cl solution (10 mL), and the aqueous layer was
extracted with Et2O (3 × 10 mL). The combined organic
layers were washed with brine (10 mL) and dried with
Na2SO4. Removal of solvent and chromatographic
1:4
17b
17a
Scheme 3
Acknowledgment
This work was supported by the National Science Foundation to
whom we are grateful.
purification afforded S-alkynyl sulfoximines 11.
Procedure B: To a solution of b-keto sulfoximine (1 mmol)
in toluene (10 mL) at –40 °C was added dropwise DIPEA
(6.0 equiv) followed by Tf2O (2.3 equiv). The solution was
stirred for 5 h. The reaction was quenched with sat. NH4Cl
(5 mL), extracted with EtOAc (3 × 10 mL), washed with
brine (10 mL), dried with Na2SO4 and concentrated in vacuo
to give an enol triflate. The triflate was purified by
chromatography, eluting with 20% EtOAc in hexane. Due to
instability of enol triflate, elimination was carried out
immediately. Into a solution of enol triflate (0.5 mmol) in
toluene (6 mL) was added DIPEA (3.0 equiv) at r.t. and the
solution was stirred at 70 °C for 4 h. The reaction was
quenched with sat. NH4Cl solution (5 mL), extracted with
EtOAc (3 × 10 mL), washed with brine, dried with Na2SO4
and concentrated in vacuo to give a colorless oil. The oil was
purified by chromatography, eluting with 20% EtOAc in
hexane, to give the pure final product.
References and Notes
(1) (a) Reggelin, M.; Zur, C. Synthesis 2000, 1. (b) Okamura,
H.; Bolm, C. Chem. Lett. 2004, 33, 482. (c) Pyne, S. Sulfur
Rep. 1999, 21, 281. (d) Johnson, C. R. Aldrichimica Acta
1985, 18, 3.
(2) (a) Lemasson, F.; Gais, H.-J.; Raabe, G. Tetrahedron Lett.
2007, 48, 8752. (b) Spohr, V.; Kaiser, J. P.; Reggelin, M.
Tetrahedron: Asymmetry 2006, 17, 50. (c) Rémy, P.;
Langner, M.; Bolm, C. Org. Lett. 2006, 8, 1209.
(d) Harmata, M.; Ghosh, S. K. Org. Lett. 2001, 3, 3321.
(3) Harmata, M.; Pavri, N. Angew. Chem. Int. Ed. 1999, 38,
2419.
(4) Back, T. G. Tetrahedron 2001, 57, 5263.
(5) Craig, D.; Rosa, V. G. Synlett 2001, 761.
(6) Leca, D.; Song, K.; Amatore, M.; Festerbank, L.; Lacote, E.;
Malacria, M. Chem. Eur. J. 2004, 10, 906.
(7) Sklute, G.; Bolm, C.; Marek, I. Org. Lett. 2007, 9, 1259.
(8) This is based on a substructure search in Scifinder Scholar.
(9) Harmata, M.; Schlemper, E. O. Tetrahedron Lett. 1987, 28,
5997.
(19) Data on selected compounds: 10a: oil. 1H NMR (500 MHz,
CDCl3): d = 7.85–7.92 (m, 4 H), 7.38–7.54 (m, 6 H), 4.70 (d,
J = 12.6 Hz, 1 H), 4.54 (d, J = 12.6 Hz, 1 H), 0.83 (s, 9 H),
–0.01 (d, J = 10.5 Hz, 6 H). 13C NMR (125.8 MHz, CDCl3):
d = 189.1, 143.5, 136.5, 133.6, 132.6, 129.5, 128.7, 128.5,
127.9, 67.8, 25.8, 20.7, 17.9, –2.6, –2.6. IR (CH2Cl2): 3064,
2949, 2921, 2855, 1679, 1446, 1274, 1160, 829 cm–1.
HRMS: m/z calcd for C20H27NO2SSiNa+: 396.1429; found:
396.1315. 10b: oil. 1H NMR (500 MHz, CDCl3): d = 7.80–
7.82 (m, 2 H), 7.26–7.50 (m, 7 H), 4.80 (d, J = 13.0 Hz, 1 H),
4.72 (d, J = 13.0 Hz, 1 H), 0.86 (s, 9 H), 0.01–0.30 (s, 6 H).
13C NMR (125.8 MHz, CDCl3): d = 191.0, 143.0, 137.8,
132.5, 132.4, 131.4, 130.8, 130.4, 128.6, 127.8, 126.8, 70.8,
17.9, –2.6, –2.7. IR (CH2Cl2): 3065, 2922, 2849, 1686, 1286,
1139, 829 cm–1. HRMS: m/z calcd for C20H26ClNO2SSiNa+:
430.1034; found: 430.1021. 10c: oil. 1H NMR (500 MHz,
CDCl3): d = 7.85–7.87 (m, 2 H), 7.48–7.57 (m, 3 H), 4.05 (d,
J = 12.5 Hz, 1 H), 4.03 (d, J = 12.5 Hz, 1 H), 2.33 (s, 3 H),
0.90 (s, 9 H), 0.05 (d, J = 11.5 Hz, 6 H). 13C NMR (125.8
(10) Bhattacharya, S. N.; Josiah, B. M.; Walton, D. R. M.
Organomet. Chem. Synth. 1971, 1, 145.
(11) For examples, see: (a) Harmata, M. Tetrahedron Lett. 1988,
29, 5229. (b) Harmata, M.; Claassen, R. J. II.; Barnes, C. L.
J. Org. Chem. 1991, 56, 5059. (c) Harmata, M.; Herron, B.
F. Tetrahedron 1991, 47, 8855. (d) Harmata, M.;
Kahraman, M.; Jones, D. E.; Pavri, N.; Weatherwax, S. E.
Tetrahedron 1998, 54, 9995.
(12) Harmata, M.; Huang, C. Adv. Synth. Catal. 2008, 350, 972.
(13) Annunriata, R.; Cinquini, M.; Cotzi, F. J. Chem. Soc., Perkin
Trans. 1 1981, 1109.
(14) Hwang, K. J.; Logusch, E. W.; Brannigan, L. H.; Thompson,
M. R. J. Org. Chem. 1987, 52, 3435.
Synlett 2008, No. 13, 2051–2055 © Thieme Stuttgart · New York

2054
M. Harmata et al.
LETTER
MHz, CDCl3): d = 191.2, 143.2, 132.7, 128.8, 127.6, 72.4,
31.4, 25.8, 17.9, –2.6, –2.7. IR (CH2Cl2): 3068, 2949, 2929,
2851, 1707, 1290, 1143, 820 cm–1. HRMS: m/z calcd for
C15H25NO2SSiNa+: 334.1267; found: 334.1262. 10d: oil. 1H
NMR (500 MHz, CDCl3): d = 7.83–7.85 (m, 2 H), 7.47–7.55
(m, 3 H), 4.14 (d, J = 12.5 Hz, 1 H), 4.00 (d, J = 12.5 Hz, 1
H), 2.72–2.78 (m, 1 H), 1.60–1.75 (m, 5 H), 1.22–1.26 (m, 5
H), 0.90 (s, 9 H), 0.03 (d, J = 12.5 Hz, 6 H). 13C NMR (125.8
MHz, CDCl3): d = 202.2, 143.3, 132.6, 128.7, 127.7, 69.3,
51.0, 28.1, 27.8, 25.8, 25.6, 25.5, 25.2, 17.9, –2.6, –2.6. IR
(CH2Cl2): 3068, 2921, 2851, 1707, 1446, 1298, 1147, 824
cm–1. HRMS: m/z calcd for C20H33NO2SSiNa+: 402.1893;
found: 402.1885. 10e: oil. 1H NMR (500 MHz, CDCl3): d =
7.86–7.87 (m, 2 H), 7.50–7.58 (m, 3 H), 4.16 (d, J = 12.5 Hz,
1 H), 4.06 (d, J = 12.5 Hz, 1 H), 3.00 (q, J = 7.0 Hz, 1 H),
1.06 (d, J = 7.0 Hz, 6 H), 0.91 (s, 9 H), 0.06 (d, J = 11.5 Hz,
6 H). 13C NMR (125.8 MHz, CDCl3): d = 203.0, 143.2,
132.6, 128.8, 127.8, 69.3, 25.8, 17.9, 17.7, 17.5, –2.6, –2.7.
IR (CH2Cl2): 3065, 2963, 2849, 1719, 1294, 1155, 829
cm–1. HRMS: m/z calcd for C17H29NO2SSiNa+: 362.1580;
found: 362.1572. 10f: oil. 1H NMR (250 MHz, CDCl3): d =
7.84–7.88 (m, 2 H), 7.51–7.59 (m, 3 H), 5.74 (ddt, J = 4.0,
7.0, 14.0 Hz, 1 H), 5.10 (m, 2 H), 4.04 (d, J = 12.5 Hz, 1 H),
4.04 (d, J = 12.5 Hz, 1 H), 2.50–2.58 (m, 2 H), 2.03 (q, finely
split, J = 7.0 Hz, 2 H), 1.65 (m, 2 H), 0.91 (s, 9 H), 0.04 (d,
J = 3.0 Hz, 6 H). 13C NMR (62.9 MHz, CDCl3): d = 199.2,
143.2, 137.7, 132.7, 128.8, 127.7, 115.3, 71.5, 43.6, 32.7,
25.8, 22.3, 17.9, –2.6, –2.7. IR (CH2Cl2): 3068, 2949, 2929,
2851, 1707, 1290, 1143, 820 cm–1. HRMS: m/z calcd for
C19H31NO2SSiNa+: 388.1737; found: 388.1729. 10g: oil. 1H
NMR (250 MHz, CDCl3): d = 7.85–7.88 (m, 2 H), 7.48–7.62
(m, 3 H), 4.05 (d, J = 12.5 Hz, 1 H), 4.05 (d, J = 12.5 Hz, 1
H), 2.60–2.84 (m, 2 H), 1.03 (t, J = 7.2 Hz, 3 H), 0.92 (s, 9
H), 0.07 (s, 3 H), 0.04 (s, 3 H). 13C NMR (62.5 MHz,
CDCl3): d = 199.7, 143.2, 132.6, 128.8, 127.7, 71.3, 37.7,
25.8, 17.9, 7.3, –2.58, –2.64. IR (CH2Cl2): 2953.9, 2921.2,
2847.6, 1715.7, 1298.9, 1147.7, 833.1, 767.7 cm–1. HRMS:
m/z calcd for C16H27NO2SSiNa+: 348.1423; found:
Hz, 1 H), 4.68 (d, J = 12.5 Hz, 1 H), 4.58 (d, J = 12.5 Hz, 1
H), 4.57 (d, J = 12.5 Hz, 1 H), 0.83 (s, 9 H), 0.81 (s, 9 H),
0.00 (s, 6 H), –0.02 (s, 6 H). 13C NMR (125.8 MHz, CDCl3):
d = 188.9, 143.6, 140.0, 133.1, 129.7, 129.1, 128.2, 68.5,
26.0, 18.2, –2.35, –2.39. IR (CH2Cl2): 2949, 2917, 2851,
1679, 1315, 1151, 1000 cm–1. HRMS: m/z calcd for
C24H48N2O4S2Si2Na+: 691.2486; found: 691.2492. 11a: oil.
1H NMR (500 MHz, CDCl3): d = 8.12–8.13 (m, 2 H), 7.32–
7.58 (m, 8 H), 1.05 (s, 9 H), 0.30 (d, J = 3.0 Hz, 6 H). 13
C
NMR (125.8 MHz, CDCl3): d = 145.5, 132.6, 132.2, 130.6,
128.8, 128.5, 127.0, 119.2, 89.8, 89.2, 31.5, 25.9, 18.2, –2.9,
–3.4. IR (CH2Cl2): 3060, 2953, 2921, 2851, 2169, 1315,
1155, 1082, 833, 673 cm–1. 11b: oil. 1H NMR (500 MHz,
CDCl3): d = 8.10–8.12 (m, 2 H), 7.22–7.58 (m, 7 H), 1.00 (s,
9 H), 0.28 (s, 6 H). 13C NMR (125.8 MHz, CDCl3): d =
145.5, 137.0, 133.8, 132.7, 131.4, 129.5, 128.8, 127.0,
126.6, 119.6, 94.0, 85.6, 25.9, 18.1, –2.9, –3.4. IR (CH2Cl2):
3064, 2953, 2929, 2851, 2177, 1470, 1327, 1160, 816 cm–1.
HRMS: m/z calcd for C20H24ClNOSSiNa+: 412.0929; found:
412.0929. 11c: oil. 1H NMR (500 MHz, CDCl3): d = 8.00–
8.02 (m, 2 H), 7.48–7.55 (m, 3 H), 1.94 (s, 3 H), 0.97 (s, 9
H), 0.20 (s, 6 H). 13C NMR (125.8 MHz, CDCl3): d = 145.7,
132.4, 128.7, 126.8, 88.8, 81.6, 25.8, 18.1, 3.9, –3.0, –3.5. IR
(CH2Cl2): 3064, 2949, 2925, 2855, 2202, 1327, 1160, 824
cm–1. HRMS: m/z calcd for C15H23NOSSiNa+: 316.1162;
found: 316.1155. 11d: oil. 1H NMR (500 MHz, CDCl3): d =
8.00–8.04 (m, 2 H), 7.49–7.53 (m, 3 H), 2.42–2.52 (m, 1 H),
1.74–1.82 (m, 4 H), 1.35–1.55 (m, 2 H), 1.20–1.34 (4 H),
0.98 (s, 9 H), 0.22 (d, J = 7.5 Hz, 6 H). 13C NMR (125.8
MHz, CDCl3): d = 146.1, 132.2, 128.7, 126.7, 96.0, 82.3,
31.1, 28.9, 25.9, 25.4, 24.6, 18.2, –2.9, –3.4. IR (CH2Cl2):
3072, 2933, 2855, 2185, 1446, 1323, 1168, 829 cm–1.
HRMS: m/z calcd for C20H31NOSSiNa+: 384.1788; found:
384.1759. 11e: oil. 1H NMR (500 MHz, CDCl3): d = 8.00–
8.02 (m, 2 H), 7.48–7.55 (m, 3 H), 2.64 (q, J = 7.0 Hz, 1 H),
1.16 (d, J = 7.0 Hz, 6 H), 0.98 (s, 9 H), 0.22 (d, J = 8.0 Hz,
6 H). 13C NMR (125.8 MHz, CDCl3): d = 145.8, 132.3,
128.7, 126.8, 97.0, 81.5, 25.8, 21.4, 21.3, 20.6, 18.1, –3.0,
–3.5. IR (CH2Cl2): 3064, 2949, 2925, 2855, 2202, 1327,
1160, 824 cm–1. HRMS: m/z calcd for C15H27NOSSiNa+:
344.1475; found: 344.1470. 11f: oil. 1H NMR (500 MHz,
CDCl3): d = 8.00–8.04 (m, 2 H), 7.49–7.55 (m, 3 H), 5.63–
5.76 (m, 1 H), 4.94–5.01 (m, 2 H), 2.30 (t, J = 7.2 Hz, 2 H),
2.08 (q, finely split, J = 7.2 Hz, 2 H), 1.60 (p, J = 7.2 Hz, 2
H), 0.98 (s, 9 H), 0.22 (d, J = 5.5 Hz, 6 H). 13C NMR (125.8
MHz, CDCl3): d = 146.0, 136.8, 132.4, 128.7, 126.8, 115.8,
92.3, 82.6, 32.6, 26.4, 25.9, 18.1, 18.1, –2.9, –3.4. IR
(CH2Cl2): d = 3068, 2949, 2852, 2193, 1442, 1335, 1164
cm–1. 11g: oil. 1H NMR (500 MHz, CDCl3): d = 8.01–8.03
(m, 2 H), 7.51–7.56 (m, 3 H), 2.31 (q, J = 7.5 Hz, 2 H), 1.15
(t, J = 7.5 Hz, 3 H), 0.98 (s, 9 H), 0.23 (s, 3 H), 0.22 (s, 3 H).
13C NMR (125.8 MHz, CDCl3): d = 145.7, 132.3, 128.6,
126.8, 93.6, 81.6, 25.8, 18.1, 12.5, 12.0, –3.01, –3.53. IR:
2953.9, 2925.3, 2847.6, 2193.8, 1474.6, 1450.1, 1331.6,
1168.2, 829.0, 775.9 cm–1. HRMS: m/z calcd for
348.1415. 10h: oil. 1H NMR (500 MHz, CDCl3): d = 7.89–
7.91 (m, 2 H), 7.49–7.58 (m, 6 H), 7.40–7.41 (m, 3 H), 6.94
(d, J = 16.0 Hz, 1 H), 4.31 (d, J = 12.5 Hz, 1 H), 4.28 (d, J =
12.5 Hz, 1 H), 0.90 (s, 9 H), 0.08 (s, 3 H), 0.05 (s, 3 H). 13
C
NMR (125.8 MHz, CDCl3): d = 188.1, 144.8, 143.2, 134.0,
132.7, 130.9, 128.8, 128.7, 128.6, 127.8, 125.3, 71.1, 25.8,
17.9, –2.51, –2.58. IR (CH2Cl2): 2953.9, 2925.3, 2855.8,
1605.4, 1323.5, 1294.8, 1147.7, 824.9 cm–1. HRMS: m/z
calcd for C22H29NO2SSiNa+: 420.1580; found: 420.1578.
10i: oil. 1H NMR (500 MHz, CDCl3): d = 7.84–7.85 (m, 2
H), 7.48–7.56 (m, 3 H), 4.00 (d, J = 12.5 Hz, 1 H), 4.00 (d,
J = 12.5 Hz, 1 H), 2.56 (dd, J = 7.0, 12.0 Hz, 2 H), 1.61–1.80
(m, 7 H), 0.88–1.28 (m, 13 H), 0.04 (d, J = 10.0 Hz, 6 H). 13
C
NMR (125.8 MHz, CDCl3): d = 198.8, 143.1, 132.6, 128.7,
127.7, 71.6, 51.8, 33.1, 32.9, 26.1, 25.9, 25.8, 17.9, –2.6,
–2.6. IR (CH2Cl2): 3064, 2921, 2855, 1711, 1298, 1143, 824
cm–1. HRMS: m/z calcd for C21H35NO2SSiNa+: 416.2050;
found: 416.2044. 10j: oil. 1H NMR (500 MHz, CDCl3): d =
7.86 (d, J = 7.5 Hz, 2 H), 7.54 (d, J = 1.5 Hz, 1 H), 7.53 (t,
J = 7.5 Hz, 1 H), 7.47 (t, J = 7.5 Hz, 2 H), 7.22 (d, J = 3.5
Hz, 1 H), 6.52 (dd, J = 1.5, 3.5 Hz, 1 H), 4.54 (d, J = 12.5 Hz,
1 H), 4.38 (d, J = 12.5 Hz, 1 H), 0.84 (s, 9 H), 0.03 (s, 3 H),
0.01 (s, 3 H). 13C NMR (125.8 MHz, CDCl3): d = 177.4,
152.8, 147.6, 143.6, 132.9, 129.0, 128.2, 119.8, 113.0, 68.2,
26.0, 18.1, –2.4. IR (CH2Cl2): 2953, 2929, 2851, 1621, 1429,
1204, 1004 cm–1. HRMS: m/z calcd for C18H25NO3SSiNa+:
386.1217; found: 386.1220. 10k: oil. 1H NMR (500 MHz,
CDCl3): d = 7.97 (s, 4 H), 7.85 (d, J = 7.5 Hz, 4 H), 7.56 (t,
J = 7.5 Hz, 2 H), 7.49 (t, J = 7.5 Hz, 4 H), 4.69 (d, J = 12.5
C16H25NOSSiNa+: 330.1318; found: 330.1316. 11i: oil. 1H
NMR (500 MHz, CDCl3): d = 8.01–8.02 (m, 2 H), 7.47–7.53
(m, 3 H), 2.17 (d, J = 6.5 Hz, 2 H), 1.66–1.72 (m, 5 H), 1.45–
1.55 (m, 1 H), 1.05–1.20 (m, 3 H), 0.98 (s, 9 H), 0.92–0.94
(m, 2 H), 0.21 (d, J = 6.5 Hz, 6 H). 13C NMR (125.8 MHz,
CDCl3): d = 146.1, 132.3, 128.6, 126.7, 92.1, 83.1, 36.5,
32.5, 26.4, 25.8, 25.8, 18.1, –2.9, –3.4. IR (CH2Cl2): 3064,
2925, 2847, 2189, 1315, 1168, 824 cm–1. HRMS: m/z calcd
for C21H33NOSSiNa+: 398.1940; found: 398.1944. 11j: oil.
1H NMR (500 MHz, CDCl3): d = 8.06 (d, J = 7.5 Hz, 2 H),
7.59 (t, J = 7.5 Hz, 1 H), 7.53 (t, J = 7.5 Hz, 2 H), 7.46 (dd,
J = 0.5, 1.5 Hz, 1 H), 6.80 (dd, J = 0.5, 1.5 Hz, 1 H), 6.42 (dd,
Synlett 2008, No. 13, 2051–2055 © Thieme Stuttgart · New York

LETTER
J = 1.5, 3.5 Hz, 1 H), 1.00 (s, 9 H), 0.27 (s, 3 H), 0.25 (s, 3
S-Alkynyl Sulfoximines
2055
H), 7.54 (t, J = 7.5 Hz, 4 H), 7.41 (s, 4 H), 1.00 (s, 18 H), 0.25
(s, 6 H), 0.24 (s, 6 H). 13C NMR (125.8 MHz, CDCl3): d =
145.3, 133.1, 132.4, 129.2, 127.4, 121.6, 92.5, 87.7, 26.1,
18.4, –2.7, –3.2. IR (CH2Cl2): 2949, 2925, 2855, 2169, 1331,
1164, 829 cm–1. HRMS: m/z calcd for C34H44N2O2S2Si2Na:
655.2275; found: 655.2279.
H). 13C NMR (125.8 MHz, CDCl3): d = 146.3, 145.4, 134.4,
133.0, 129.2, 127.5, 120.3, 111.7, 94.4, 79.7, 26.1, 18.4,
–2.8, –3.4. IR (CH2Cl2): 2949, 2925, 2851, 2161, 1470,
1323, 1168 cm–1. HRMS: m/z calcd for C18H23NO2SSiNa+:
368.1111; found: 368.1112. 11k: oil. 1H NMR (500 MHz,
CDCl3): d = 8.06 (d, J = 7.5 Hz, 4 H), 7.58 (t, J = 7.5 Hz, 2
Synlett 2008, No. 13, 2051–2055 © Thieme Stuttgart · New York