Synthesis of amino-functionalized sulfonimidamides and their application in the enantioselective henry reaction

Article abstract of DOI:10.1021/jo100326x

Amino-functionalized sulfonimidamides have been prepared by aziridinium ring-opening reactions and nucleophilic substitutions of sulfonimidoyl chlorides. Whereas the former reactions afford separable diastereomeric products, the latter provide single ster

Full text of DOI:10.1021/jo100326x

pubs.acs.org/joc
Synthesis of Amino-Functionalized Sulfonimidamides and Their
Application in the Enantioselective Henry Reaction
Marianne Steurer and Carsten Bolm*
Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52056 Aachen, Germany
carsten.bolm@oc.rwth-aachen.de
Received February 22, 2010
Amino-functionalized sulfonimidamides have been prepared by aziridinium ring-opening reactions
and nucleophilic substitutions of sulfonimidoyl chlorides. Whereas the former reactions afford
separable diastereomeric products, the latter provide single stereoisomers. Application of the
resulting stereochemically homogeneous sulfonimidamides as ligands in asymmetric copper-cata-
lyzed Henry reactions of aromatic aldehydes with nitromethane led to products with enantioselec-
tivities up to 95% ee in good yields.
Introduction
context, aziridinations of olefins,3 iminations of sulfides
and sulfoxides,3a,4 and CH aminations5 have been studied
Sulfonimidamides, the aza-analogues of sulfonamides,
were first described in the 1960s by Levchenko et al.1 Since
then, the main interest for these compounds centered around
their bioactivity2 and their use as chiral nitrene precursors in
metal-catalyzed nitrogen transfer reactions. In the latter
€
by Malacria, Dodd, Muller, and others. In all of those
reactions sulfonimidamides served as reagents being applied
in stoichiometric quantities. Surprisingly, to the best of our
knowledge, applications of sulfonimidamides as chiral li-
gands in asymmetric metal catalysis have not yet been
described. The only example of a sulfonimidamide being
part of a catalytic system involves a proline-derived organo-
catalyst, which we recently reported to promote solvent-free
asymmetric aldol reactions leading to products with high
enantioselectivities.6
(1) Levchenko, E. S.; Derkach, N. Y.; Kirsanov, A. V. Zh. Obshch. Khim.
1962, 32, 1208.
(2) See, for example: (a) Ray, E. J.; Toth, J. E. CA 2085297 A1, 1993.
(b) Cathers, B. E. Dissertation, University of Kansas, Lawrence, KS, 1996.
(c) Toth, J. E.; Grindey, G. B.; Ehlhardt, W. J.; Ray, J. E.; Boder, G. B.; Bewley,
J. R.; Klingerman, K. K.; Gates, S. B.; Rinzel, S. M.; Schultz, R. M.; Weir, L. C.;
Worzalla, J. F. J. Med. Chem. 1997, 40, 1018. (d) Lang, H. J.; Jansen, H.-W.;
Schwark, J.-R.; Kleemann, H.-W.; Jung, O.; Schafer, H.-L.; Linz, W.; Kramer, W.;
Scholkens, B.; Falk, E. WO 9746226 A2, 1997. (e) Kleemann, H.-W.; Brendel, J.;
Schwark, J.-R.; Weichert, A.; Lang, H. J.; Albus, U.; Scholz, W. EP 771788 A2,
1997. (f) Cathers, B. E.; Schloss, J. V. Bioorg. Med. Chem. Lett. 1999, 9, 1527.
(g) Saxena, A.; Agrawal, V. K.; Khadikar, P. V. Oxid. Commun. 2003, 26, 9. (h)
Paulini, R.; Breuninger, D.; von Deyn, W.; Bastiaans, H. M. M.; Beyer, C.;
Anspaugh, D. D.; Oloumi-Sadeghi, H. WO 156336 A1, 2009.
On the basis of our expertise in sulfoximine chemistry7 we
hypothesized that the inherent stereogenic center at sulfur
and the two nitrogens of a sulfonimidoyl amino moiety could
be useful for the design and generation of effective ligands for
asymmetric metal catalysis. For evaluating this assumption,
amino-substituted sulfonimidamides such as A appeared
suitable because they combined the well-known features of
(3) For copper catalyses, see: (a) Leca, D.; Toussaint, A.; Mareau, C.;
^
Fensterbank, L.; Lacote, E.; Malacria, M. Org. Lett. 2004, 6, 3573. (b)
Di Chenna, P. H.; Robert-Peillard, F.; Dauban, P.; Dodd, R. H. Org. Lett.
2004, 6, 4503. (c) For rhodium catalyses, see: Fruit, C.; Robert-Peillard, F.;
(6) Worch, C.; Bolm, C. Synlett 2009, 2425.
€
Bernardinelli, G.; Muller, P.; Dodd, R. H.; Dauban, P. Tetrahedron:
Asymmetry 2005, 16, 3484.
(4) Collet, F.; Dodd, R. H.; Dauban, P. Org. Lett. 2008, 10, 5473.
(7) For reviews on the use of sulfoximines in metal catalysis, see: (a)
Harmata, M. Chemtracts 2003, 16, 660. (b) Okamura, H.; Bolm, C. Chem.
Lett. 2004, 32, 482. (c) Bolm, C. In Asymmetric Synthesis with Chemical and
€
(5) (a) Liang, C.; Robert-Peillard, F.; Fruit, C.; Muller, P.; Dodd, R. H.;
Dauban, P. Angew. Chem., Int. Ed. 2006, 45, 4641. (b) Liang, C.; Collet, F.;
€
Robert-Peillard, F.; Muller, P.; Dodd, R. H.; Dauban, P. J. Am. Chem. Soc.
2008, 130, 343. (c) Rashatasakhan, P.; Harmata, M. Chemtracts 2006, 19,
€
Biological Methods; Enders, D., Jager, K.-E., Eds.; Wiley-VCH: Weinheim,
Germany, 2007; p 149. (d) Worch, C.; Mayer, A. C.; Bolm, C. In Organosulfur
Chemistry in Asymmetric Synthesis; Toru, T., Bolm, C., Eds.; Wiley-VCH:
Weinheim, Germany, 2008; p 209. (e) For a review on chiral sulfur-containing
ligands in catalysis, see: Pellissier, H. Tetrahedron 2007, 63, 1297.
143.
DOI: 10.1021/jo100326x
r
Published on Web 03/26/2010
J. Org. Chem. 2010, 75, 3301–3310 3301
2010 American Chemical Society

Steurer and Bolm
JOCArticle
SCHEME 1. Synthesis of Sulfonimidamides 4 via Sulfonimidoyl Chlorides 2
TABLE 1. Substrate Scope in the Synthesis of Sulfonimidamides 4
Starting from (S)-1
vicinal trans-cyclohexanediamines with a still unexplored
sulfonimidoyl amino group.
entry
sulfinamide
amine
3a
3a
sulfonimidamide
yield (%)
1a
2a
3
(S)-1a
(S)-1b
(S)-1a
(S)-1a
(S)-1b
(S)-1b
(S)-1a
(S)-1a
(S)-1b
(S)-1b
(S)-1a
(S)-1a
(S)-4a
(S)-4b
80
92
48
60
43
48
74
78
51
59
74
69
(S,S)-3b
(R,R)-3b
(S,S)-3b
(R,R)-3b
(S,S)-3c
(R,R)-3c
(S,S)-3c
(R,R)-3c
(R,R)-3d
(R,R)-3e
(S,S,S)-4c
(S,R,R)-4d
(S,S,S)-4e
(S,R,R)-4f
(S,S,S)-4g
(S,R,R)-4h
(S,S,S)-4i
(S,R,R)-4j
(S,R,R)-4k
(S,R,R)-4l
4
5
6b
7
8
9
10
11
12c
Following this concept a strategy for the synthesis of such
compounds was developed, and subsequently the resulting
products were tested in enantioselective copper-catalyzed
nitroaldol reactions.
aIn analogy rac-1a and rac-1b have been applied. bUse of 1.7 equiv of
diamine. cUse of 3 equiv of diamine.
Results and Discussion
enantiomers of the chiral derivatives were accessible by effi-
cient resolution protocols of the racemic diamines.11,12
The substrate scope of this approach (method A) was
wide, and the results for transformations starting from (S)-1
are summarized in Table 1. In general, amino-substituted
sulfonimidamides 4 were obtained in satisfactory to high
yields, and commonly N-benzoyl-protected sulfinamide 1a
gave better results than sulfinamide 1b having a N-Boc
protecting group.
The well-studied stereochemistry of such reaction se-
quence (oxidative chlorination and subsequent attack of a
nucleophile at sulfur) suggested a high stereospecificity with
inversion of configuration at the stereogenic sulfur (via a
retention-inversion pathway).9d,e Accordingly, all reactions
between (S)-1 and enantiopure diamines 3b-e provided single
diastereomers (Table 1, entries 3-12). Epimers were never
observed. Furthermore, the reaction between (S)-1a and
cyclohexylamine (3a) led to a single enantiomer (>99% ee)
as proven by HPLC analysis (Table 1, entry 1).13 In the
conversion of (R,R)-1,2-cyclohexanediamine (3e), a 3-fold
excess of the diamine was used (instead of the commonly
used 1.9 equiv) in order to prevent the formation of the
corresponding biscoupled product (entry 12). In this man-
ner, sulfonimidamide 4l with a free amino functionality was
accessed, offering the possibility for further derivatization at
this position.
Syntheses of the Sulfonimidamides. Amino-substituted sul-
fonimidamides of type A have three stereogenic centers, and
for obtaining them as single stereoisomers two preparative
routes were devised. Method A involved couplings of sulfon-
imidoyl chlorides 2 with amino components 3 (Scheme 1).
All chiral reaction partners were readily available in enantio-
merically pure form, and stereospecific couplings led to
isomerically homogeneous products. More specifically,
stereoselective oxidative chlorinations of enantiopure sulfin-
amides (S)-18,9e with tert-butylhypochlorite at 0 °C gave
enantiopure sulfonimidoyl chlorides 2,9,10 which were directly
(without isolation) converted into 4 by treatment with
(di)amines 3 in the presence of Cs2CO3 at room temperature.
(Di)amines 3 were either commercially available, or both
(8) For the preparation of enantiopure sulfinamides 1a and 1b, see:
(a) Backes, B. J.; Dragoli, D. R.; Ellman, J. A. J. Org. Chem. 1999, 64,
5472. (b) Dong, Z.; Pyne, S. G. Sulfur Lett. 2002, 25, 37. (c) Savile, C. K.;
Magloire, V. P.; Kazlauskas, R. J. J. Am. Chem. Soc. 2005, 127, 2104.
(9) For oxidative chlorinations of sulfinamides with t-BuOCl, see: (a)
Johnson, C. R.; Wamsgans, A. J. Org. Chem. 1979, 44, 2278. (b) Harmata,
M. Tetrahedron Lett. 1989, 30, 437. (c) Kluge, R.; Hocke, H.; Schulz, M.;
Schilke, F. Phosphorous, Sulfur Silicon Relat. Elem. 1999, 149, 179. (d)
Reggelin, M.; Junker, B. Chem.;Eur. J. 2001, 7, 1232. (e) Worch, C.;
Atodiresei, I.; Raabe, G.; Bolm, C. Chem.;Eur. J. 2010, 16, 677.
(10) For alternative oxidative chlorination methods of sulfinamides see,
~
for example: Mancheno, O. G.; Bolm, C. Beilstein J. Org. Chem. 2007, 3, 25
and references therein.
(11) Enantiopure 3b and 3c were obtained by resolution of the corre-
sponding racemic trans-diamines with mandelic acid following a similar
protocol as described in (a) Schiffers, I.; Rantanen, T.; Schmidt, F.; Berg-
mans, W.; Zani, L.; Bolm, C. J. Org. Chem. 2006, 71, 2320. (b) Schiffers, I.;
Bolm, C. Org. Synth. 2008, 85, 106. (c) For the synthesis of racemic trans-3b
and trans-3c and an alternative method for obtaining the diamines enantio-
merically pure, see: Gonzalez-Sabin, J.; Gotor, V.; Rebolledo, F. Chem.;
Eur. J. 2004, 10, 5788.
(12) In the graphic presentations of this article we follow the suggestions
by Maehr for stereochemical notations. For a summary, see: Maehr, H.
J. Chem. Educ. 1985, 62, 114.
(13) Suitable HPLC conditions for the ee analysis of sulfonimidamide 4b
could not be found.
3302 J. Org. Chem. Vol. 75, No. 10, 2010

Steurer and Bolm
JOCArticle
SCHEME 2. Aziridinium Route to Amino-Substituted Sulfoni-
midamides
the nitro group with carbon or heteroatom nucleophiles.18
Of particular interest are catalytic and asymmetric versions
of Henry reactions. Along these lines, various metal-based
systems and organocatalytic approaches have recently been
developed.19 Since some catalysts involved 1,2-cyclohexane-
diamine-derived compounds,20 we hypothesized that sulfon-
imidamides 4 could affect these transformations.21 In order
to test this idea, copper-catalyzed additions of nitromethane
to p-nitrobenzaldehyde (8a) and benzaldehyde (8b) in the
presence of sulfonimidamide (S,R,R)-4d were examined.
First, the effects of the base, solvent, temperature, and
copper source on the formations of products 9 were studied
(Table 2).
In a typical experiment, the copper source and the sulfon-
imidamide were combined in dichloromethane, and the
resulting mixture was kept at room temperature overnight
to allow complex formation. For the subsequent catalysis,
the solvent was changed (to the one listed in Table 2). With-
out preformation of the complex the yield of 9 was signifi-
cantly lower (for example, compare Table 2, entries 8 and 9).
Changing the catalyst amount from 10 to 5 mol % affected
the yield negatively and the ee deceased (Table 2, entry 2 vs
entry 3). In general, alcohols were the most suitable solvents,
and the best results were achieved when the reactions were
carried out in ethanol (compare entries 1, 8, 15-17). In this
solvent, the yields reached the 80-90% range, and an ee of
88% (for 9b) was observed (Table 2, entry 22). Lowering the
reaction temperature from ambient temperature to 0 °C led
to a decrease in both yield and enantioselectivity (entry 4). At
40 °C the ee (of product 9a) was only 54% (Table 2, entry 5).
Consequently, the subsequent experiments were performed
at ambient temperature. Among the bases, pyridine and
4-methylpyrimidine gave the best results, with the latter
being superior to the former. A screening of various copper
sources using 8b as substrate showed that all salts, except
CuCN, were effective leading to good enantioselectivities.
With CuCl the highest ee (83%) and a yield of 82% was
achieved (Table 2, entry 8). Finally it was shown that neither
lowering nor raising the concentration affected the results
positively (Table 2, entries 19 and 20). Although a higher
dilution led to a slight increase in enantioselectivity, the yield
dropped from 82% to 62% (Table 2, entries 8 vs 20). An
important observation was made when the reaction was
performed (organocatalytically) with 10 mol % of (S,R,R)-
4d in absence of a metal. In this case, the other enantiomer
was preferentially formed. Albeit under these conditions the
yield (20%) and the ee (8%) of 9b were low (Table 2, entry
21), the result indicated that the previously performed
As alternative for the synthesis of amino-substituted
sulfonimidamides, an aziridinium ring-opening sequence14
involving the use of enantiomerically pure N-benzoyl-pro-
tected sulfonimidamide (S)-7 (method B) was developed
(Scheme 2). In contrast to method A, which provided single,
isomerically pure products, method B led to diastereomers,
which had to be separated. Advantages of this approach were
the formation of two products in a single synthetic transfor-
mation and the availability of a wide range of racemic trans-
aminoalcohols, which could easily be prepared in a single
step from cyclohexene oxide.
Method B was used for the synthesis of amino-substituted
sulfonimidamides (S,S,S)-4c, (S,R,R)-4d, (S,S,S)-4g, and
(S,R,R)-4h. In one-pot reactions racemic trans-piperidinyl-
and trans-morpholinyl-substituted aminoalcohols 5a and 5b,
respectively, were first mesylated, and treatment of the
resulting intermediates with enantiopure sulfonimidamide
(S)-7 gave amino-substituted sulfonimidamides 4c/4d and
4g/4h as ca. 1:1 pairs of diastereomers in acceptable overall
yields. The intermediacy of aziridinium salts 6 guaranteed
that only trans-products were generated, and in both cases
the diastereomers could easily be separated by flash chro-
matography providing stereochemically homogeneous sam-
ples.15
Catalytic Application in the Henry Reaction. Henry reac-
tions are nitroaldol-type additions of nitroalkanes to alde-
hydes generating products that often are versatile inter-
mediates for organic synthesis. Transformations of the
resulting β-nitroalkanes include, for example, reductions to
the respective aminoalcohols,16 Nef-oxidations to alde-
hydes, ketones or carboxylic acids,17 and substitutions of
(19) For recent reviews on Henry reactions, see: (a) Boruwa, J.; Gogoi,
N.; Saikia, P. P.; Barua, N. C. Tetrahedron: Asymmetry 2006, 17, 3315.
(b) Palomo, C.; Oiarbide, M.; Laso, A. Eur. J. Org. Chem. 2007, 2561. (c)
Wang, A. X. In Name Reactions for Homologations; Li, J. J., Ed.; John Wiley &
Sons, Inc.: Hoboken, NJ, 2009; p 404.
(20) For recent applications of catalysts with a 1,2-cyclohexanediamino
skeleton in asymmetric Henry reactions, see: (a) Arai, T.; Watanabe, M.;
Fujiwara, A.; Yokoyama, N.; Yanagisawa, A. Angew. Chem., Int. Ed. 2006,
45, 5978. (b) Bandini, M.; Piccinelli, F.; Tommasi, S.; Umani-Ronchi, A.;
Ventrici, C. Chem. Commun. 2007, 616. (c) Constable, E. C.; Zhang, G.;
Housecroft, C. E.; Neuburger, M.; Schaffner, S.; Woggon, W.-D. New J.
Chem. 2009, 33, 1064. (d) Zhang, G.; Yashima, E.; Woggon, W.-D. Adv.
Synth. Catal. 2009, 351, 1255. (e) Kowalczyk, R.; Kwiatkowski, P.;
Skarzewski, J.; Jurczak, J. J. Org. Chem. 2009, 74, 753 and references therein.
(21) For the use of a sulfonamide-based vicinal diamine type ligand in a
Henry reaction, see: Arai, T.; Takashita, R.; Endo, Y.; Watanabe, M.;
Yanagisawa, A. J. Org. Chem. 2008, 73, 4903.
(14) (a) Periasamy, M.; Seenivasaperumal, M.; Padmaja, M.; Rao, V. D.
ARKIVOC 2004, viii, 4. (b) Anaya de Parrodi, C.; Juaristi, E. Synlett 2006,
2699 and references therein.
(15) Attempts to use N-Boc-protected sulfonimidamide 7b in combination
with aminoalcohol 5a or sulfonimidamide 7a with a dibenzylated aminoalcohol
remained unsuccessful, and complex product mixtures were formed.
(16) (a) Poupart, M.-A.; Fazal, G.; Goulet, S.; Mar, L. T. J. Org. Chem.
1999, 64, 1356. (b) Bergmeier, S. C. Tetrahedron 2000, 56, 2561.
(17) (a) Narayana, C.; Reddy, N. K.; Kabalka, G. W. Synth. Commun.
1992, 22, 2587. (b) Coppola, G. M.; Schuster, H. F. R-Hydroxy Acids in
Enantioselective Syntheses; Wiley-VCH: Weinheim, Germany, 1997. (c) Matt,
C.; Wagner, A.; Mioskowski, C. J. Org. Chem. 1997, 62, 234. (d) For a review on
Nef oxidations, see: Ballini, R.; Petrini, M. Tetrahedron 2004, 60, 1017.
(18) Tamura, R.; Kamimura, A.; Ono, N. Synthesis 1991, 423.
J. Org. Chem. Vol. 75, No. 10, 2010 3303

Steurer and Bolm
JOCArticle
TABLE 2. Evaluation of Reaction Conditions in Copper-Catalyzed Henry Reactions with Sulfonimidamide 4d as Liganda
entry
1d
RCHO
solvent
base (equiv)
pyridine (1.37)
pyridine (1.37)
pyridine (1.37)
pyridine (1.37)
pyridine (1.37)
Cu source
CuCl
time (h)
yield (%)b
ee (%)c
8ae
8ae
8ae
8ae
8ae
8ae
8b
8b
8b
8b
8b
8b
8b
8b
8b
8b
8b
8b
8b
8b
8b
8b
MeOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
EtOH
MeNO2
i-PrOH
PhOEt
EtOH
EtOH
EtOH
EtOH
EtOH
17
4
4
16.5
4
4
83
93
90
64
88
85
76
82
32
72
62
74
40
50
58
50
4
60 (R)
61 (R)
47 (R)
45 (R)
54 (R)
66 (R)
82 (R)
83 (R)
74 (R)
62 (R)
79 (R)
75 (R)
10 (R)
51 (R)
42 (R)
81 (R)
70 (R)
82 (R)
82 (R)
88 (R)
8 (S)
2d
CuCl
CuCl
CuCl
CuCl
CuCl
CuCl
CuCl
CuCl
CuI
3d,f
4d,g
5h
6
7
4-Me-pyrimidine (1.37)
4-Me-pyrimidine (1.37)
4-Me-pyrimidine (1.18)
4-Me-pyrimidine (1.18)
4-Me-pyrimidine (1.18)
4-Me-pyrimidine (1.18)
4-Me-pyrimidine (1.18)
4-Me-pyrimidine (1.18)
4-Me-pyrimidine (1.18)
4-Me-pyrimidine (1.18)
4-Me-pyrimidine (1.18)
4-Me-pyrimidine (1.18)
4-Me-pyrimidine (0.5)
4-Me-pyrimidine (1.18)
4-Me-pyrimidine (1.18)
4-Me-pyrimidine (1.18)
4-Me-pyrimidine (1.18)
25
21
19
25
21
21
18.5
25
21
18
25
21
21
19.5
17.5
19.5
8
9i
10
11
12
13
14
15
16
17
18
19j
20k
21
22l
CuBr
CuOAc
CuCN
(CuOTf)2 Tol
3
CuCl
CuCl
CuCl
CuCl
CuCl
CuCl
---
48
64
62
20
66
CuCl
88 (R)
aMethod: CuCl (10 mol %) and sulfonimidamide (S,R,R)-4d (11 mol %) were stirred at rt in CH2Cl2 (0.5 M) overnight. After removal of the solvent,
the solid was redissolved in the indicated solvent (0.6 mL) and MeNO2 (3 mmol, 10 equiv), base, and aldehyde 8a or 8b (0.3 mmol) were added. Then, the
mixture was stirred at room temperature for the indicated period of time. bYield after flash chromatography. cEnantiomeric ratios were determined by
HPLC analysis using a Chiralcel OD-H column. Absolute configurations of the major enantiomers are given in parentheses. dCuCl-ligand complex
e
f
g
preformation within 3 h. Use of 0.5 mmol of the aldehyde. Use of 5 mol % of CuCl and 5.5 mol % of (S,R,R)-4d. Reaction performed at 0 °C.
hReaction performed at 40 °C. iNo CuCl-ligand complex preformation. j1 M concentration. k0.25 M concentration. lUse of 10 mol % of (S,R,R)-4d.
copper catalyses could have been affected by the 10% excess
of the sulfonimidamides with respect to the copper loading
(use of 11 and 10 mol %, respectively). This assumption was
confirmed by an experiment with equimolar amounts of
CuCl and (S,R,R)-4d, which led to product 9b with a slightly
increased ee (88 vs 83%; Table 2, entries 22 and 8).
Using the optimized reaction conditions (complex prefor-
mation, EtOH as solvent, ambient temperature, 4-Me-
pyrimidine as base, metal-to-ligand ratio of 1:1), sulfonimid-
amides 4a-l were applied in the nitroaldol reaction between
benzaldehyde (8b) and nitromethane. The results are sum-
marized in Table 3.
Cyclohexylamine-derived sulfonimidamides (S)-4a and
(S)-4b were almost inactive, leading to 9b in very low yields
(Table 3, entries 1 and 2). Presumably, the lack of the second
nitrogen on the cyclohexane ring did not allow sufficient
complexation of the metal to the ligands. This hypothesis
was supported by the observation that with (S)-4a and (S)-4b
no color change occurred during the initial complex forma-
tion phase, in contrast to the reaction behavior of diamine-
derived sulfonimidamides, where the originally colorless
solution turned green upon complex formation. It is also
noteworthy that the application of (S,R,R)-4k having an
amide nitrogen at the cyclohexane ring gave a catalyst with
only moderate activity and low enantioselectivity (Table 3,
entry 11). Also in this case the coordinating ability might
have been too low to provide a high-activity copper catalyst.
Sulfonimidamide (S,R,R)-4l having a primary amino group
at the cyclohexane ring led to a catalyst with reasonable
enantioselectivity, providing 9b with 39% ee in 37% yield
(Table 3, entry 12). Compared to the system with sulfonimid-
amide (S,R,R)-4k this one showed improved properties, but
both could not compete with catalysts bearing diamine-
derived sulfonimidamides 4c-j having tertiary amino groups
at the cyclohexane ring. Those proved to be the best ligands
for the copper catalysis, providing products with good to
high enantioselectivities in moderate to high yields (Table 3,
entries 3-10). In general, the use of benzoyl-protected sulfon-
imidamides afforded products in higher yields and with
slightly better enantioselectivities than their Boc-protected
counterparts. Comparing the effects of ligands with piperidi-
nyl and morpholinyl substituents [sulfonimidamides 4c-f
(Table 3, entries 3-6) versus 4g-j (entries 7-10)], the latter
proved more effective, suggesting that the higher basicity of
the nitrogen improved the catalyst performance. Overall, the
most effective ligand was (S,R,R)-4h leading to (R)-9b with
95% ee in 79% yield (Table 3, entry 8). Interestingly, its
diastereomer (S,S,S)-4g gave the product with almost the
same ee (92%), but the absolute configuration was opposite
and the yield only moderate (47%; Table 3, entry 7). This
result showed that the direction of asymmetric induction was
determined by the two stereogenic centers at the cyclohexyl
moiety and that the sulfonimidoyl amino group had a
supporting effect for the catalyst activity and selectivity.
The impact of the sulfur part of the ligand was further
demonstrated by the application of sulfonamide-based
3304 J. Org. Chem. Vol. 75, No. 10, 2010

Steurer and Bolm
JOCArticle
TABLE 3. Screening of Sulfonimidamides 4a-l in the Henry Reaction
between Benzaldehyde (8b) and Nitromethanea
TABLE 4. Substrate Scope in the Copper-Catalyzed Nitroaldol
Reactiona
entry aldehyde 8; R = sulfonimidamide yield of 9 (%)b ee (%)c
entry
sulfonimidamide
yield (%)b
ee (%)c
1
2
3
4
5
6
7
8
9
4-(NO2)-C6H4- (8a)
C6H5- (8b)
C6H5- (8b)
4-Cl-C6H4- (8c)
2-(MeO)-C6H4- (8d)
2-(MeO)-C6H4- (8d)
2-Me-C6H4- (8e)
1-naphthyl- (8f)
1-naphthyl- (8f)
(S,R,R)-4h
(S,R,R)-4h
(S,S,S)-4g
(S,R,R)-4h
(S,R,R)-4h
(S,S,S)-4g
(S,R,R)-4h
(S,R,R)-4h
(S,S,S)-4g
(S,R,R)-4h
82 (9a)
79 (9b)
47 (9b)
61 (9c)
83 (9d)
63 (9d)
72 (9e)
70 (9f)
48 (9f)
nd (9g)
88 (R)
95 (R)
92 (S)
90 (R)
95 (R)
92 (S)
92 (R)
93 (R)
88 (S)
1
2
(S)-4a
(S)-4b
11
3
0
nd
3
(S,S,S)-4c
(S,R,R)-4d
(S,S,S)-4e
(S,R,R)-4f
(S,S,S)-4g
(S,R,R)-4h
(S,S,S)-4i
(S,R,R)-4j
(S,R,R)-4k
(S,R,R)-4l
(R,R)-10
68
66
40
28
47
79
69
41
34
37
66
81 (S)
88 (R)
55 (S)
64 (R)
92 (S)
95 (R)
77 (S)
85 (R)
4 (S)
4d
5
6
7
8
9
10
11
12
13
10 cyclohexyl- (8g)
aFor reaction conditions, see Experimental Section. bYield after
flash chromatography; nd = not determined. cEnantiomeric ratios were
determined by HPLC analysis. Absolute configurations of the major
enantiomers are given in parentheses.
39 (R)
12 (R)
aMethod: CuCl (10 mol %) and sulfonimidamide 4 (or sulfonamide
10; 10 mol %) were stirred at rt in CH2Cl2 (3.4 mL) overnight. After
removal of the solvent, the solid was redissolved in EtOH (1.2 mL), and
MeNO2 (10 equiv), 4-methylpyrimidine (1.18 equiv), and benzaldehyde
(8b, 0.6 mmol, 1 equiv) were added. Stirring at ambient temperature
overnight was followed by solvent evaporation and flash chromatogra-
phy (see Experimental Section for details). bYield after flash chroma-
tography. cEnantiomeric ratios were determined by HPLC analysis;
nd = not determined. Absolute configurations of the major enantiomers
are given in parentheses. dUse of 0.3 mmol of 8b.
tivities could not be reached. This aspect as well as attempts
to decrease the metal/ligand loading (of 10 mol %) will be
addressed in subsequent studies, which shall focus on further
ligand modifications.
In summary, we developed two synthetic routes for the
preparation of enantiopure amino-functionalized sulfonimid-
amides. Whereas single isomeric products are obtained using
a nucleophilic substitution route, diastereomeric products,
which can readily be separated, are formed in a reaction
sequence involving an aziridinium ring opening as key step.
Both approaches lead to stereochemically homogeneous pro-
ducts in good to high yields. We have further shown that the
resulting amino-functionalized sulfonimidamides are promis-
ing chiral ligands in the asymmetric copper-catalyzed Henry
reactions between aromatic aldehydes and nitromethane. In
combination with copper chloride they catalytically lead to
productswithupto95%ee ingoodtohigh yields. By applying
diastereomeric ligands, both enantiomers of the products are
accessible with almost the same enantioselectivities. Com-
pared to a reaction with an analogous sulfonamide-based
catalyst, the sulfonimidamides proved superior. Since this is,
to the best of our knowledge, the first asymmetric metal
catalysis with complexes bearing chiral sulfonimidamides as
ligands, we regard the results as a promising starting point,
which will eventually guide us to further discoveries.
cyclohexanediamine 10,22 which led to a copper catalyst with
good activity (66% yield in the formation of 9b) but low
enantioselectivity (12% ee; Table 3, entry 13). Clearly, the sul-
fonimidamides were superior to the analogous sulfonamide.
In order to evaluate the substrate scope, various aldehydes
were applied under the optimized conditions in reactions
with nitromethane using the (S,R,R)-4h/CuCl catalyst sys-
tem. In addition, three of these Henry-type reactions were
also performed with (S,S,S)-4g as ligand. The results are
shown in Table 4.
All reactions with aromatic aldehydes (Table 4, entries
1-9) led to products with high ee values ranging from 88%
to 95%. In contrast, aliphatic cyclohexylcarbaldehyde (8g,
entry 10) reacted sluggishly, giving a mixture of unidentified
products. The best results were achieved in catalyses with
sulfonimidamide (S,R,R)-4h/CuCl. Compared to those ob-
tained in analogous reactions with the diastereomeric ligand
(S,S,S)-4g, the ee values and yields of the products were
superior in all cases. Nevertheless, also with (S,S,S)-4g the
product ees were high (88-92%), and noteworthy, applying
this ligand instead of (S,R,R)-4h provided access to the
enantiomeric series of the products. This aspect is particu-
larly valuable because both sulfonimidamides (S,R,R)-4h
and (S,S,S)-4g can be obtained in a single synthetic trans-
formation by the aziridinium route (Scheme 2).
Experimental Section
General. All reactions were carried out in oven-dried flasks
under an inert atmosphere of argon using Schlenk technique.
THF and CH2Cl2 were dried over Na/benzophenone and CaH2,
respectively, and freshly distilled before using. For the Henry
reactions EtOH of p.A. grade was used. All liquid aldehydes
except o-tolylaldehyde were distilled prior to use. p-Tolylsulfin-
amide,8,23 piperidinyl-, morpholinyl-, and acetyl-substituted
In comparison to published data from Henry reactions
with related copper catalysts,20d,21 the system reported here
compares well, despite the fact that superior enantioselec-
(23) (a) For the preparation of racemic p-tolylsulfinamide see, for exam-
ple: Krasnova, L. B.; Yudin, A. K. J. Org. Chem. 2004, 69, 2584. (b) For the
preparation of enantiopure (S)-p-tolylsulfinamide, see: Davis, F. A.; Zhang,
Y.; Andemichael, Y.; Fang, T.; Fanelli, D. L.; Zhang, H. J. Org. Chem. 1999,
64, 1403 and references therein.
(22) (a) Bisai, A.; Prasad, B. A.; Bhanu; Singh, V. K. Tetrahedron Lett.
2005, 46, 7935. (b) Corrigendum: Bisai, A.; Prasad, B. A.; Bhanu; Singh,
V. K. Tetrahedron Lett. 2006, 47, 1487.
J. Org. Chem. Vol. 75, No. 10, 2010 3305

Steurer and Bolm
JOCArticle
diamines (3b,11 3c,11 and 3d,24 respectively), and aminoalco-
hols 511,25 were prepared analoguosly to literature proce-
dures. (1R,2R)-1,2-Cyclohexanediamine was purchased with
a 99% purity. tert-Butylhypochlorite was prepared according
to literature procedures and stored at -20 °C.26 Absolute
configurations of β-nitroalcohols 9 were assigned comparing
the measured optical rotations to literature values.27 Flash
chromatography was done on silica gel 60 (40-63 μm; F254
plates). Analysis of TLCs was done either using UV light
(254 nm) or KMnO4 stain. NMR spectra were recorded at
400 or 300 MHz (1H NMR) and 100 or 75 MHz (13C NMR).
Chemical shifts are given in ppm relative to TMS (δ = 0 ppm)
or solvent residual peaks (CDCl3; 1H, δ = 7.26 ppm; 13C, δ =
77.0 ppm) as internal standards. Coupling constants J are given
in Hz, and coupling patterns are described as bs = broad singlet,
d = doublet, t = triplet, m = multiplet, dd = doublet of doub-
let, etc. [R]D values are given in deg cm3 g-1 dm-1; concentra-
additional 20 min at the same temperature and then for 2 h at
0 °C. The reaction was stopped by addition of a saturated
aqueous solution of NaHCO3 (10 mL), and the thereby formed
white precipitate was dissolved by addition of water. The solu-
tion was diluted with CH2Cl2, and the phases were separated.
The aqueous phase was extracted four times with CH2Cl2, and
the combined organic phases were washed with brine. The
solution was dried over MgSO4, and the solvent was removed
under reduced pressure. The raw material was purified by flash
chromatography (silica gel, pentane/ethylacetate = 2:1) to af-
ford (S)-1b (1.925 g, 8.043 mmol, 83%, >99% ee) as a white so-
lid. 1H NMR (CDCl3, 400 MHz) δ 1.51 (s, 9H), 2.42 (s, 3H), 6.66
(bs, 1H), 7.34 (d, J = 8.2 Hz, 2H), 7.62 (d, J = 8.2 Hz, 2H); 13
C
NMR (CDCl3, 100 MHz) δ 21.5, 28.1, 83.5, 124.6, 129.9, 140.5,
142.3, 152.3 (1 qC not observed); mp 107-112 °C; IR (KBr) ν
3135, 1712, 1412, 1367, 1238, 1151, 1093, 1063, 812, 709 cm-1
;
MS (EI, 70 eV) m/z 199 ([M - C4H8]þ, 79%), 139 (52%), 108
(25%), 57 (100%). Anal. Calcd for C12H17NO3S: C, 56.45; H,
6.71; N, 5.49. Found: C, 56.25; H, 6.81; N, 5.41. [R]21D þ110.3
(c 1.0, CHCl3); HPLC (Chiralcel OG, 20 °C, 210 nm, 95/5
Heptan/i-PrOH, 1.0 mL/min) tR = 12.8 min (S), 18.3 min (R).
rac-tert-Butyl-(4-tolylsulfinyl)-carbamate (rac-1b)10. Pre-
pared in analogy to (S)-1b starting from rac-4-toluenesulfina-
mide (651 mg, 4.191 mmol), 2.5 equiv of n-BuLi and 1.4 equiv
of di-tert-butyl dicarbonate. Flash chromatography (silica
gel, pentane/ethylacetate = 2:1) afforded rac-1b (635 mg,
2.653 mmol, 63%) as a white solid, mp 90-93 °C.
3
3
3
tion c is listed in g (100 mL)-1. Melting points were determined
3
in open capillaries and are uncorrected.
(S)-N-(4-Tolylsulfinyl)-benzamide [(S)-1a]9e. (S)-4-Toluene-
sulfinamide (860 mg, 5.540 mmol, 1 equiv) was dissolved in
dry THF (22 mL) and cooled to -78 °C. Immediately after
addition of n-BuLi (7.6 mL, 12.16 mmol, 1.6 M in hexane,
2.2 equiv) benzoic anhydride (1.504 g, 6.648 mmol, 1.2 equiv)
was added at -78 °C. Stirring was continued for additional 2 h
at the same temperature and subsequently for 22 h at room
temperature. The reaction was stopped by addition of a satu-
rated aqueous solution of NaHCO3 (10 mL), and the thereby
formed white precipitate was dissolved by addition of CH2Cl2.
The phases were separated, and the aqueous phase was extracted
four times with CH2Cl2. The combined organic phases were
dried over MgSO4, and the solvent was removed under reduced
pressure. To the yellow oil was added diethylether (5 mL), and
then the ether was removed again in vacuum. This procedure
was repeated until the oil solidified. The solid was filtered
and washed with diethylether, affording (S)-1a as a white solid
(985 mg, 3.798 mmol, 69%, >99% ee). 1H NMR (CDCl3, 400
MHz) δ 2.44 (s, 3H), 7.35 (d, J = 8.2 Hz, 2H), 7.44 (t, J = 7.6
Hz, 2H), 7.56 (tt, J1 = 1.3 Hz, J2 = 7.6 Hz, 1H), 7.65 (d, J = 8.2
Hz, 2H), 7.79-7.84 (m, 2H), 8.53 (bs, 1H); 13C NMR (CDCl3,
100 MHz) δ 21.6, 124.7, 127.8, 128.7, 130.0, 131.5, 133.0, 140.6,
142.5, 167.2; mp 122-124 °C; IR (KBr) ν 3158, 3070, 1672, 1450,
1403, 1242, 1088, 1053, 1026, 882, 805, 780, 700 cm-1; MS (EI,
70 eV) m/z 259 ([M], 83%), 211 (5%), 139 (33%), 108 (63%), 105
(100%), 77 (37%). Anal. Calcd for C14H13NO2S: C, 64.84; H,
5.05; N, 5.40. Found: C, 64.48; H, 5.19; N, 5.34. [R]21D þ106.4 (c
0.51, CHCl3); HPLC (Chiralcel OD-H, 20 °C, 210 nm, 95/5
Heptan/i-PrOH, 1.0 mL/min) tR = 26.2 min (R), 34.5 min (S).
rac-N-(4-Tolylsulfinyl)-benzamide (rac-1a)10. Prepared in
analogy to (S)-1a starting from rac-4-toluenesulfinamide
(1.0 g, 6.442 mmol). The product was purified by recrystalliza-
tion from ethylacetate (100 mL) to afford rac-1a (1.17 g, 4.512
mmol, 70%) as a white solid, mp (decomp) 107 °C.
(S)-N-Benzoyl-4-toluenesulfonimidamide [(S)-7]9e. To a solu-
tion of (S)-N-(4-tolylsulfinyl)-benzamide (1a, 501 mg, 1.932
mmol, 1 equiv) in dry THF (25 mL), t-BuOCl26 (328 μL, 2.900
mmol, 1.5 equiv) was added dropwise at 0 °C. After stirring for
2 h at 0 °C, an aqueous solution of NH3 (10 mL, 25 wt %)
was added at 0 °C, and stirring was continued for 45 min at
room temperature. Subsequently, water (15 mL) was added, the
phases were separated, and the aqueous phase was extracted
four times with ethylacetate. The combined organic phases
were washed with brine, and the aqueous phase was extracted
once with ethylacetate. All organic phases were combined and
dried over MgSO4. After removal of the solvent under reduced
pressure, raw material 7 (514 mg, 1.874 mmol, 97%) was
obtained as a white solid, which was sufficiently pure for further
reactions. An analytical sample was purified by flash chroma-
tography (silica gel, pentane/ethylacetate = 1:1). 1H NMR
(CDCl3, 400 MHz) δ 2.40 (s, 3H), 6.37 (bs, 2H), 7.29 (d, J =
8.0 Hz, 2H), 7.35-7.41 (m, 2H), 7.49 (tt, J1 = 7.3 Hz, J2 = 1.4
Hz, 1H), 7.88-7.93 (m, 2H), 8.09-8.14 (m, 2H); 13C NMR
(CDCl3, 100 MHz) δ 21.6, 126.5, 127.9, 129.3, 129.7, 132.2,
135.2, 138.1, 144.3, 173.3; mp 140-144 °C; IR (KBr) ν 3164,
3066, 1599, 1572, 1551, 1324, 1297, 1219, 1151, 1095, 978, 839,
806, 716 cm-1; MS (EI, 70 eV) m/z 275 ([M þ H]þ, 2%), 197
(7%), 108 (100%), 104 (29%). Anal. Calcd for C14H14N2O2S: C,
61.29; H, 5.14; N, 10.21. Found: C, 61.28; H, 5.14; N, 10.21.
[R]21 þ69.9 (c 1.0, CHCl3); HPLC (Chiralcel OJ, 20 °C,
D
(S)-tert-Butyl-(4-tolylsulfinyl)-carbamate [(S)-1b]9e. (S)-4-To-
luenesulfinamide (1.510 g, 9.728 mmol, 1 equiv) was dissolved in
dry THF (40 mL) and cooled to -78 °C. Immediately after
addition of n-BuLi (15.20 mL, 24.320 mmol, 1.6 M in hexane,
2.5 equiv), di-tert-butyl dicarbonate (3.240 g, 14.845 mmol,
1.5 equiv) was added at -78 °C. Stirring was continued for
210 nm, 85/15 Heptan/i-PrOH, 0.7 mL/min) tR = 37.4 min
(R), 54.5 min (S).
General Procedure for the Synthesis of Sulfonimidamides 4.
Nucleophilic Substitution Route. Under an inert atmosphere of
argon t-BuOCl26 (0.578 mmol, 1.5 equiv) was added dropwise
to a solution of sulfinamide 1 (0.386 mmol, 1 equiv) in dry THF
(3 mL) at 0 °C. After stirring for 2 h at 0 °C, (di)amine 3 (0.733
mmol, 1.9 equiv) and Cs2CO3 (0.771 mmol, >99%, 2 equiv)
were added at 0 °C, and subsequently the solution was stirred
overnight at room temperature. The reaction was stopped by
addition of water (5 mL), and the phases were separated. The
aqueous phase was extracted three times with CH2Cl2, and the
combined organic phases were washed with brine. After drying
over MgSO4 and removal of the solvent under reduced pressure,
the product was purified by flash chromatography on silica gel.
(24) Mitchell, J. M.; Finney, N. S. Tetrahedron Lett. 2000, 41, 8431.
(25) See for example: Chakraborti, A. K.; Rudrawar, S.; Kondaskar, A.
Eur. J. Org. Chem. 2004, 3597.
(26) (a) t-BuOCl reacts violently when exposed to light or in contact with
rubber. For safety instructions, see: Teeter, H. M.; Bell, E. W. Org. Synth.
1952, 32, 20. (b) For a convenient preparation of t-BuOCl using NaOCl, see:
Mintz, M. J.; Walling, C. Org. Synth. 1969, 49, 9.
(27) Selvakumar, S.; Sivasankaran, D.; Singh, V. K. Org. Biomol. Chem.
2009, 7, 3156.
3306 J. Org. Chem. Vol. 75, No. 10, 2010

Steurer and Bolm
JOCArticle
(S)-N-Benzoyl-4-toluenesulfonimid-N0-cyclohexylamide [(S)-
4a]. Prepared according to the general procedure by starting
from sulfinamide (S)-1a (250 mg, 0.964 mmol), amine 3a (210 μL,
1.832 mmol), and Cs2CO3 (628 mg, 1.928 mmol). Flash chroma-
tography (silicagel, pentane/diethylether/Et3N = 2:2:0.3) yielded
product (S)-4a (273 mg, 0.766 mmol, 80%, >99% ee) as a white
solid. 1H NMR (CDCl3, 400 MHz) δ 1.11-1.38 (m, 4H),
1.40-1.56 (m, 2H), 1.56-1.67 (m, 2H), 1.67-1.78 (m, 1H),
2.00-2.12 (m, 1H), 2.41 (s, 3H), 3.17-3.29 (m, 1H), 7.30 (d,
J = 8.3 Hz, 2H), 7.33-7.40 (m, 2H), 7.43-7.49 (m, 1H),
7.63-7.75 (m, 1H), 7.90 (d, J = 8.3 Hz, 2H), 8.09-8.15 (m,
2H); 13C NMR (CDCl3, 100 MHz) δ 21.6, 24.5, 24.6, 25.1, 33.1,
34.6, 34.7, 51.9, 127.0, 127.8, 129.2, 129.6, 131.9, 135.6, 137.4,
143.9, 172.5; mp 88-90 °C; IR (KBr) ν 2930, 2854, 1605, 1573,
1448, 1317, 1291, 1239, 1173, 1144, 1094, 1066, 990, 945, 809, 710
cm-1; MS (EI, 70 eV) m/z 357 ([M], 1%), 313 (9%), 211 (19%),
155 (21%), 146 (28%), 139 (17%), 108 (100%), 105 (75%). Anal.
Calcd for C20H24N2O2S: C, 67.38; H, 6.79; N, 7.86. Found: C,
observed; mp 127-128 °C; IR (KBr) ν 2932, 2856, 1602, 1572,
1312, 1292, 1258, 1095, 810, 781, 708 cm-1; MS (EI, 70 eV) m/z
320 ([M - C7H5NO], 2%), 229 (1%), 181 (100%), 164 (7%).
Anal. Calcd for C25H33N3O2S: C, 68.30; H, 7.57; N, 9.56.
Found: C, 68.21; H, 7.58; N, 9.30. [R]22D þ146.6 (c 0.75, CHCl3).
(S)-N-Benzoyl-4-toluenesulfonimid-N0-[(1R,2R)-2-piperidin-1-
yl-cyclohexyl]amide [(S,R,R)-4d]. Prepared according to the gen-
eral procedure starting from sulfinamide (S)-1a (100 mg, 0.386
mmol), diamine (R,R)-3b (134 mg, 0.733 mmol), and Cs2CO3
(251 mg, 0.771 mmol). Flash chromatography (silica gel, pen-
tane/diethylether/Et3N = 4:1:0.5) afforded product (S,R,R)-4d
(102 mg, 0.232 mmol, 60%) as a white solid. 1H NMR (CDCl3,
300 MHz) δ 0.99-1.31 (m, 5H), 1.38-1.94 (m, 10H), 2.22-2.45
(m, 6H), 2.64-2.79 (m, 2H), 3.32-3.44 (m, 1H), 7.25-7.40 (m,
4H), 7.40-7.48 (m, 1H), 7.93 (d, J = 8.3 Hz, 2H), 8.08-8.14 (m,
2H); 13C NMR (CDCl3, 75 MHz) δ 21.5, 23.1, 24.2, 24.6, 25.2,
26.1, 32.7, 49.3, 53.0, 68.0, 127.5, 127.7, 129.3, 129.4, 131.5, 136.4,
138.8, 143.3; mp (decomp) 156 °C; IR (KBr) ν 2933, 2857, 1617,
1575, 1450, 1313, 1283, 1223, 1142, 935, 904, 801, 711, 683 cm-1
;
67.09; H, 6.93; N, 7.74. [R]24 þ123.6 (c 1.0, CHCl3); HPLC
D
MS (EI, 70 eV) m/z 440 ([M], 2%), 320 (6%), 181 (100%), 164
(37%), 124 (21%), 105 (32%), 96 (21%), 84 (31%); HRMS calcd
for C25H33N3O2S ([M]) 439.2288, found 439.2288. [R]24D -31.8
(c 1.0, CHCl3).
(Chiralcel AD-H, 20 °C, 230 nm, 90:10 heptane/i-PrOH, 0.5 mL/
min) tR = 39.0 min (S), 55.15 min (R).
rac-N-Benzoyl-4-toluenesulfonimid-N0-cyclohexylamide (rac-4a).
Prepared according to the general procedure by starting from
racemic sulfinamide 1a (100 mg, 0.386 mmol), amine 3a (84 μL,
0.733 mmol), and Cs2CO3 (251 mg, 0.772 mmol). Flash chroma-
tography (silicagel, pentane/diethylether/Et3N = 2:2:0.3) yielded
product rac-4a (114 mg, 0.320 mmol, 83%) as a white solid, mp
105 °C; the spectroscopic data are in agreement with those
reported for (S)-4a.
(S)-N-tert-Butyloxycarbonyl-4-toluenesulfonimid-N0-[(1S,2S)-
2-piperidin-1-yl-cyclohexyl]amide [(S,S,S)-4e]. Prepared accord-
ing to the general procedure starting from sulfinamide (S)-1b
(250 mg, 0.979 mmol), diamine (S,S)-3b (339 mg, 1.860 mmol) and
Cs2CO3 (638 mg, 1.958 mmol). Flash chromatography (silica gel,
pentane/diethylether/Et3N = 4:2:0.5) afforded product (S,S,S)-
4e (183 mg, 0.420 mmol, 43%) as a light-brown solid. 1H NMR
(CDCl3, 400 MHz) δ 0.94-1.24 (m, 3H), 1.28-1.57 (m, 17H),
1.58-1.83 (m, 3H), 2.06-2.24 (m, 5H), 2.39-2.49 (m, 4H), 2.58
(dt, J1 = 4.1 Hz, J2 = 10.6 Hz, 1H), 7.32 (d, J = 8.2 Hz, 2H), 7.82
(d, J = 8.2 Hz, 2H); 13C NMR (CDCl3, 100 MHz) δ 21.5, 22.7,
24.1, 24.6, 25.2, 26.2, 28.0, 33.1, 45.9, 49.1, 52.9, 67.4, 79.7, 127.4,
129.4, 135.8, 143.3, 156.7; mp 107-108 °C; IR(KBr) ν 2935, 2855,
2806, 1666, 1450, 1364, 1279, 1251, 1162, 1142, 1089, 961, 890, 867
cm-1; MS (EI, 70 eV) m/z 436 ([M þ H]þ 2%), 362 (16%), 319
(37%), 181 (100%), 165 (56%), 137 (26%), 124 (35%), 84 (45%);
HRMS calcd for C23H37N3O3S ([M]) 435.2550, found 435.2538.
[R]24D þ69.4 (c 0.5, CHCl3).
(S)-N-tert-Butyloxycarbonyl-4-toluenesulfonimid-N0-cyclohexyl-
amide [(S)-4b]. Prepared according to the general procedure
starting from sulfinamide (S)-1b (250 mg, 0.979 mmol), amine
3a (213 μL, 1.860 mmol), and Cs2CO3 (638 mg, 1.958 mmol).
Flash chromatography (silica gel, pentane/diethylether/Et3N =
2:2:0.3) afforded product (S)-4b (319 mg, 0.905 mmol, 92%) as a
white solid. 1H NMR (CDCl3, 400 MHz) δ 1.07-1.45 (m, 14H),
1.45-1.63 (m, 3H), 1.65-1.75 (m, 1H), 1.95-2.06 (m, 1H), 2.43
(s, 3H), 3.06-3.18 (m, 1H), 6.35 (d, J = 4.9 Hz, 1H), 7.26-7.37
(d, J = 8.2 Hz, 2H), 7.81-7.88 (d, J = 8.2 Hz, 2H); 13C NMR
(CDCl3, 100 MHz) δ 21.6, 24.6, 25.1, 28.1, 33.2, 34.5, 51.4, 80.1,
127.7, 129.5, 137.0, 143.5, 157.0; mp 122-124 °C; IR (KBr) ν
2974, 2931, 2857, 1668, 1450, 1363, 1272, 1160, 1074, 1033, 991,
903, 860, 816, 786, 756 cm-1; MS (EI, 70 eV) m/z 353 ([M], 2%),
297 (6%), 279 (54%), 235 (35%), 215 (23%), 197 (42%), 171
(44%), 154 (21%), 139 (34%), 108 (100%), 98 (92%), 57 (67%).
Anal. Calcd for C18H28N2O3S: C, 61.33; H, 8.01; N, 7.95.
Found: C, 61.07; H, 8.14; N, 7.82. [R]24D þ62.4 (c 1.0, CHCl3).
rac-N-tert-Butyloxycarbonyl-4-toluenesulfonimid-N0-cyclohe-
xylamide (rac-4b). Prepared according to the general procedure
starting from sulfinamide rac-1b (100 mg, 0.392 mmol), amine
3a (90 μL, 0.744 mmol), and Cs2CO3 (255 mg, 0.783 mmol).
Flash chromatography (silica gel, pentane/diethylether/Et3N =
2:2:0.3) afforded product rac-4b (130 mg, 0.369 mmol, 94%) as a
white solid, mp 110-115 °C; the spectroscopic data are in
agreement with those reported for (S)-4b.
(S)-N-Benzoyl-4-toluenesulfonimid-N0-[(1S,2S)-2-piperidin-1-
yl-cyclohexyl]amide [(S,S,S)-4c]. Prepared according to the
general procedure starting from sulfinamide (S)-1a (250 mg,
0.964 mmol), diamine (S,S)-3b (334 mg, 1.832 mmol), and
Cs2CO3 (628 mg, 1.928 mmol). Flash chromatography (silica
gel, pentane/diethylether/Et3N = 4:1:0.5) afforded product (S,
S,S)-4c (205 mg, 0.466 mmol, 48%) as a white solid. 1H NMR
(CDCl3, 300 MHz) δ 0.97-1.31 (m, 3H), 1.33-1.53 (m, 3H),
1.56-1.88 (m, 7H), 2.13-2.57 (m, 9H), 2.60-2.81 (m, 1H),
7.27-7.41 (m, 4H), 7.42-7.52 (m, 1H), 7.88-7.98 (m, 2H),
8.12-8.27 (m, 2H), 1 NH not observed; 13C NMR (CDCl3, 75
MHz) δ 21.5, 23.1, 24.2, 24.8, 25.2, 26.4, 33.4, 49.5, 53.8, 67.8,
127.4, 127.8, 129.5, 129.6, 131.7, 136.1, 136.3, 143.7, 1qC not
(S)-N-tert-Butyloxycarbonyl-4-toluenesulfonimid-N0-[(1R,2R)-
2-piperidin-1-yl-cyclohexyl]amide [(S,R,R)-4f]. Prepared accord-
ing to the general procedure starting from sulfinamide (S)-1b
(300 mg, 1.175 mmol), diamine (R,R)-3b (363 mg, 1.991 mmol,
1.7 equiv), and Cs2CO3 (766 mg, 2.350 mmol, 2.0 equiv). Flash
chromatography (silica gel, pentane/diethylether/Et3N = 4:1:0.5)
afforded product (S,R,R)-4f (246 mg, 0.565 mmol, 48%) as a
light-brown solid. 1H NMR (CDCl3, 400 MHz) δ 0.84-1.24
(m, 3H), 1.31-1.50 (m, 13H), 1.61 (quint, J = 5.4 Hz, 4H),
1.66-1.85 (m, 3H), 2.20-2.34 (m, 3H), 2.38 (s, 3H), 2.59 (quint.,
J = 5.4 Hz, 2H), 3.18 (td, J = 4.0 Hz, J = 10.6 Hz, 1H), 7.24 (d,
J = 8.2 Hz, 2H), 7.83 (d, J = 8.2 Hz, 2H), 1 NH not observed; 13
C
NMR (CDCl3, 100 MHz) δ 21.5, 22.8, 24.1, 24.5, 25.2, 25.9, 28.1,
32.1, 49.2, 53.0, 67.6, 79.6, 127.5, 129.1, 138.1, 143.1, 157.2; mp
126-128 °C; IR (KBr) ν 2968, 2930, 2855, 2807, 1655, 1450, 1366,
1277, 1243, 1142, 1095, 904, 869 cm-1; MS (EI, 70 eV) m/z 436
([M], 6%), 362 (5%), 319 (13%), 181 (100%), 164 (21%); HRMS
calcd for C23H37N3O3S ([M]) 435.2550, found 435.2540. [R]24
D
-30.9 (c 1.0, CHCl3).
(S)-N-Benzoyl-4-toluenesulfonimid-N0-[(1S,2S)-2-morpholin-4-
yl-cyclohexyl]amide [(S,S,S)-4g]. Prepared according to the gen-
eral procedure starting from sulfinamide (S)-1a (150 mg, 0.578
mmol), diamine (S,S)-3c (203 mg, 1.099 mmol), and Cs2CO3 (377
mg, 1.157 mmol). Flash chromatography (silica gel, pentane/
diethylether = 1:1) afforded product (S,S,S)-4g (189 mg, 0.428
1
mmol, 74%) as a white solid. H NMR (CDCl3, 400 MHz) δ
1.00-1.27 (m, 3H), 1.36-1.49 (m, 1H), 1.60-1.70 (m, 1H),
J. Org. Chem. Vol. 75, No. 10, 2010 3307

Steurer and Bolm
JOCArticle
1.70-1.79 (m, 1H), 1.80-1.88 (m, 1H), 2.24-2.39 (m, 5H), 2.41
(s, 3H), 2.43-2.51 (m, 1H), 2.72 (dt, J1 = 4.1 Hz, J2 = 10.6 Hz,
1H), 3.75-3.81 (m, 4H), 7.30 (d, J = 8.2 Hz, 2H), 7.35-7.41
(m, 2H), 7.44-7.50 (m, 1H), 7.93 (d, J = 8.2 Hz, 2H), 8.16-8.20
(m, 3H); 13C NMR (CDCl3, 100 MHz) δ 21.6, 23.2, 24.1, 25.1,
33.4, 48.4, 53.8, 67.1, 67.2, 127.0, 127.7, 129.3, 129.6, 131.8, 135.8,
136.3, 143.9, 172.2; mp 178-180 °C; IR (KBr) ν 2934, 2860, 1606,
1572, 1450, 1291, 1259, 1114, 1019, 922, 812, 750, 717 cm-1; MS
(EI, 70 eV) m/z 441 ([M], 1%), 398 (1%), 354 (1%), 321 (2%),
183 (100%), 166 (14%). Anal. Calcd for C24H31N3O3S: C, 65.28;
H, 7.08; N, 9.52. Found: C, 65.14; H, 7.04; N, 9.47. [R]24D þ169.5
(c 1.0, CHCl3).
1279, 1250, 1161, 1140, 1112, 1018, 956, 906, 865, 813, 765, 736
cm-1; MS (EI, 70 eV) m/z 438 ([M], 5%), 364 (10%), 321 (19%),
183 (100%), 166 (51%), 139 (27%), 126 (19%), 96 (25%), 57
(36%); HRMS calcd for C22H35N3O4S ([M]) 437.2343, found
437.2349. [R]24D -23.4 (c 1.0, CHCl3).
(S)-N-Benzoyl-4-toluenesulfonimid-N0-[(1R,2R)-2-acetylamino
cyclohexyl]amide [(S,R,R)-4k]. Prepared according to the general
procedure startingfrom sulfinamide (S)-1a (250 mg, 0.946 mmol),
diamine (R,R)-3d (286 mg, 1.832 mmol), and Cs2CO3 (628 mg,
1.928 mmol). Flash chromatography (silica gel, pentane/ethyl-
acetate = 1:3) afforded product (S,R,R)-4k (295 mg, 0.713 mmol,
74%) as a white solid. 1H NMR (CDCl3, 400 MHz) δ 1.03-1.23
(m, 2H), 1.23-1.45 (m, 2H), 1.59-1.80 (m, 3H), 1.99 (s, 3H),
2.13-2.23 (m, 1H), 2.42 (s, 3H), 3.12-3.24 (m, 1H), 3.67-3.78
(m, 1H), 6.26 (d, J = 6.9 Hz, 1H), 7.06-7.17 (bs, 1H), 7.28-7.40
(m, 4H), 7.43-7.50 (m, 1H), 7.90 (d, J = 8.1 Hz, 2H), 8.07-8.12
(m, 2H); 13C NMR (CDCl3, 100 MHz) δ 21.7, 23.5, 24.4, 24.9,
32.6, 33.3, 53.1, 56.3, 127.2, 127.9, 129.3, 129.7, 132.0, 135.4,
137.6, 144.1, 171.2, 172.7; mp 80-83 °C; IR (KBr) ν 2934, 2859,
1627, 1571, 1544, 1447, 1315, 1282, 1239, 1141, 1092, 1067, 810,
712 cm-1; MS (EI, 70 eV) m/z 414 ([M], 1%), 293 (1%), 203
(21%), 155 (88%), 139 (40%), 105 (100%), 96 (90%), 77 (39%);
HRMS calcd for C22H27N3O3S ([M]) 413.1768, found 413.1767.
[R]24D þ102.5 (c 0.5, CHCl3).
(S)-N-Benzoyl-4-toluenesulfonimid-N0-[(1R,2R)-2-morpholin-
4-yl-cyclohexyl]amide [(S,R,R)-4h]. Prepared according to the
general procedure starting from sulfinamide (S)-1a (511 mg,
1.971 mmol), diamine (R,R)-3c (690 mg, 3.744 mmol), and
Cs2CO3 (1.284 g, 3.941 mmol). Flash chromatography (silica
gel, pentane/diethylether/Et3N = 2:1:0.5) afforded product (S,R,
1
R)-4h (678 mg, 1.535 mmol, 78%) as a white solid. H NMR
(CDCl3, 400 MHz) δ 0.94-1.32 (m, 4H), 1.48-1.60 (m, 1H),
1.71-1.82 (m, 1H), 1.82-1.95 (m, 2H), 2.23-2.33 (m, 1H),
2.33-2.50 (m, 6H), 2.66-2.79 (m, 2H), 3.43 (td, J = 4.0 Hz,
J = 10.7 Hz, 1H), 3.77 (t, J = 4.5 Hz, 4H), 7.30 (d, J = 8.4 Hz,
2H), 7.33-7.42 (m, 2H), 7.43-7.50 (m, 1H), 7.88-7.95 (m, 2H),
8.08-8.14 (m, 2H); 13C NMR (CDCl3, 100 MHz) δ 21.6, 23.0,
24.1, 25.2, 32.5, 48.2, 53.0, 67.0, 67.2, 127.3, 127.8, 129.2, 129.4,
131.7, 135.8, 138.3, 143.6, 172.6; mp 106-108 °C; IR (KBr) ν
2932, 2861, 1615, 1577, 1451, 1311, 1279, 1224, 1172, 1140, 1114,
1067, 1015, 940, 905, 803, 718 cm-1; MS (EI, 70 eV) m/z 442 ([M],
1%), 399 (1%), 355 (1%), 321 (2%), 231 (1%), 183 (100%), 166
(14%), 105 (10%). Anal. Calcd for C24H31N3O3S: C, 65.28; H,
7.08; N, 9.52. Found: C, 65.12; H, 7.06; N, 9.38. [R]24D -39.2 (c
1.0, CHCl3).
(S)-N-tert-Butyloxycarbonyl-4-toluenesulfonimid-N0-[(1S,2S)-
2-morpholin-4-yl-cyclohexyl]amide [(S,S,S)-4i]. Prepared accord-
ing to the general procedure starting from sulfinamide (S)-1b (200
mg, 0.783 mmol), diamine (S,S)-3c (274 mg, 1.488 mmol), and
Cs2CO3 (510 mg, 1.567 mmol). Flash chromatography (silica gel,
pentane/diethylether = 1:1 to elute nonpolar byproducts, pen-
tane/diethylether/Et3N = 2:1:0.5 to elute the product) afforded
product (S,S,S)-4i (175 mg, 0.400 mmol, 51%) as a white solid.
1H NMR (CDCl3, 300 MHz) δ 0.97-1.40 (m, 4H), 1.41 (s, 9H),
1.56-1.87 (m, 4H), 2.15-2.30 (m, 4H), 2.37-2.48 (m, 4H), 2.63
(dt, J1 = 4.2 Hz, J2 = 10.6 Hz, 1H), 3.57-3.69 (m, 4H), 6.88 (bs,
1H), 7.31 (d, J = 8.4 Hz, 2H), 7.82 (d, J = 8.4 Hz, 2H); 13C NMR
(CDCl3, 75 MHz) δ 21.5, 22.9, 24.1, 25.1, 28.1, 33.2, 48.1, 53.0,
67.0, 67.0, 80.0, 127.4, 129.7, 136.3, 143.8, 1 qC not observed; mp
150-153 °C; IR (KBr) ν 2974, 2935, 2858, 2821, 1664, 1452,
1363, 1279, 1252, 1139, 1111, 1089, 1067, 1017, 960, 894, 865, 783,
753 cm-1; MS (EI, 70eV) m/z 438 ([M], 1%), 419 (1%), 364 (9%),
321 (13%), 183 (100%), 166 (36%); HRMS calcd for
(S)-N-Benzoyl-4-toluenesulfonimid-N0-[(1R,2R)-2-amino-cyclo-
hexyl]amide [(S,R,R)-4l]. Prepared according to the general pro-
cedure starting from sulfinamide (S)-1a (300 mg, 1.157 mmol) with
(R,R)-1,2-cyclohexanediamine (R,R)-3e (396 mg, 3.471 mmol,
3 equiv) and Cs2CO3 (754 mg, 2.314 mmol). A first flash chroma-
tography (silica pentane/diethylether = 1:3 to elute nonpolar by-
products, EtOH/acetone = 1:1 to elute the product) afforded a
fraction of pure product (S,R,R)-4l (209 mg) as a yellow solid and
an impure fraction of (S,R,R)-4l. A second chromatography of
the impure fraction (silica gel, acetone/EtOH = 3:2, then acetone/
EtOH = 1:1) afforded another 87 mg of pure product (S,R,R)-4l
(overall, 296 mg, 0.797 mmol, 69%) as a yellow solid. 1H NMR
(CDCl3, 400 MHz) δ 0.99-1.27 (m, 4H), 1.51-1.67 (m, 3H),
2.00-2.07 (m, 1H), 2.42 (s, 3H), 2.65 (dt, J1 = 10.2 Hz, J2 = 3.8
Hz, 1H), 2.98 (dt, J1 = 10.2 Hz, J2 = 3.8 Hz, 1H), 4.12 (bs, 3H),
7.30 (d, J = 8.2 Hz, 2H), 7.36 (t, J = 7.5 Hz, 2H), 7.47 (tt, J1 = 7.4
Hz, J2 = 1.2 Hz, 1H), 7.91 (d, J = 8.4 Hz, 2H), 8.09-8.14 (m, 2H);
13C NMR (CDCl3, 100 MHz) δ 21.6, 24.5, 25.0, 32.2, 34.2, 55.1,
59.0, 127.0, 127.9, 129.4, 129.7, 132.1, 135.6, 138.0, 143.9, 173.0;
mp 79-82 °C;IR(KBr) ν2932, 2859, 1598, 1543, 1447, 1318, 1288,
1141, 1117, 1091, 902, 839, 808, 713 cm-1; MS (EI, 70 eV) m/z 372
([M], 2%), 251 (3%), 139 (18%), 113 (100%), 105 (32%), 96
(95%); HRMS calcd for C20H26N3O2S ([M þ H]þ) 372.1740,
found 372.1742. [R]21D þ83.04 (c 0.42, CHCl3).
Synthesis of (S)-N-Benzoyl-4-toluenesulfonimid-N0-[(1S,2S)-
2-piperidin-1-yl-cyclohexyl]amide [(S,S,S)-4c] and (S)-N-Ben-
zoyl-4-toluenesulfonimid-N0-[(1R,2R)-2-piperidin-1-yl-cyclohex-
yl]amide [(S,R,R)-4d] by the Aziridinium Route. Under an inert
atmosphere of argon methanesulfonyl chloride (18 μL, 0.229
mmol, 1.2 equiv) was added dropwise to a solution of (()-trans-
2-piperidin-1-yl-cyclohexanol (35 mg, 0.191 mmol, 1 equiv) in
dry THF (1.5 mL) at 0 °C. Subsequently the mixture was stirred
for 5 min at 0 °C and then for 3 h at room temperature. After
addition of triethylamine (133 μL, 0.959 mmol, 5 equiv) the
solution was stirred for an additional 1 h, and then (S)-N-
benzoyl-4-toluenesulfonimidamide [(S)-7, 157 mg, 0.572 mmol,
3 equiv] and water (0.2 mL) were added. After the solution was
stirred overnight at room temperature, the phases were sepa-
rated, and the aqueous phase was extracted three times with
ethylacetate. The combined organic phases were washed with an
aqueous solution of NaHCO3 (5 wt %) and dried over MgSO4.
After removal of the solvent under reduced pressure, the pro-
ducts were purified by flash chromatography (silica gel, pen-
tane/diethylether/Et3N = 4:1:0.5). The first fraction afforded
C22H36N3O4S ([M þ H]þ) 438.2421, found 438.2407. [R]24
D
þ89.7 (c 1.0, CHCl3).
(S)-N-tert-Butyloxycarbonyl-4-toluenesulfonimid-N0-[(1R,2R)-
2-morpholin-4-yl-cyclohexyl]amide [(S,R,R)-4j]. Prepared accord-
ing to the general procedure starting from sulfinamide (S)-1b
(200 mg, 0.783 mmol), diamine (R,R)-3c (274 mg, 1.488 mmol),
and Cs2CO3 (510 mg, 1.567 mmol). Flash chromatography (silica
gel, pentane/diethylether/Et3N = 2:1:0.3) afforded product (S,R,
1
R)-4j (203 mg, 0.464 mmol, 59%) as a white solid. H NMR
(CDCl3, 400 MHz) δ 0.79-0.95 (m, 1H), 1.02-1.30 (m, 3H),
1.35-1.56 (m, 10H), 1.63-1.82 (m, 2H), 1.82-2.00 (m, 1H),
2.19-2.32 (m, 1H), 2.31-2.51 (m, 5H), 2.63-2.79 (m, 2H), 3.30
(dt, J1 = 3.6 Hz, J2 = 10.6 Hz, 1H), 3.70-3.87 (m, 4H), 7.28 (d,
J = 8.0Hz, 2H), 7.86 (d, J = 8.0 Hz, 2H), 1 NH not observed; 13
C
NMR (CDCl3, 100 MHz) δ 21.6, 22.8, 24.1, 25.2, 28.2, 32.0, 48.2,
53.0, 66.9, 67.1, 80.1, 127.7, 129.3, 138.0, 143.5, 157.4; mp
143-145 °C; IR (KBr) ν 2932, 2860, 2812, 1650, 1452, 1366,
3308 J. Org. Chem. Vol. 75, No. 10, 2010

Steurer and Bolm
JOCArticle
(S,S,S)-4c (26 mg, 0.059 mmol, 31%) as a white solid, and the
second fraction afforded (S,R,R)-4d (27 mg, 0.064 mmol, 33%)
as a white solid.
The purities of (S,S,S)-4c and (S,R,R)-4d were equal to the
ones obtained by the nucleophilic substitution route. For ana-
lytical data see the protocol of nucleophilic substitution path-
way.
HPLC (Chiralcel OD-H, 20 °C, 210 nm, 85:15 heptane/i-PrOH,
0.8 mL/min) tR = 12.5 min (R), 15.2 min (S); the spectroscopic
data are in agreement with those reported in the literature.27
(R)-1-(4-Chlorophenyl)-2-nitro-ethanol [(R)-9c]. Obtainedusing
sulfonimidamide (S,R,R)-4h (26.5 mg, 0.060 mmol) and aldehyde
8c (84.3 mg, 0.600 mmol) according to the general procedure.
Flash chromatography (silica gel, pentane/diethylether = 3:1)
afforded (R)-9c (74 mg, 0.367 mmol, 61%, 90% ee) as a colorless
oil. 1H NMR (CDCl3, 300 MHz) δ 3.00 (bs, 1H), 4.48 (dd, J1 =
3.4 Hz, J2 = 13.4 Hz, 1H), 4.57 (dd, J2 = 13.4 Hz, J3 = 9.2 Hz,
1H), 5.44 (dd, J1 = 3.4 Hz, J3 = 9.2 Hz, 1H), 7.31-7.41 (m, 4H);
13C NMR (CDCl3, 75 MHz) δ 70.3, 80.9, 127.3, 129.2, 134.8,
Synthesis of (S)-N-Benzoyl-4-toluenesulfonimid-N0-[(1S,2S)-
2-morpholin-4-yl-cyclohexyl]amide [(S,S,S)-4g] and (S)-N-Ben-
zoyl-4-toluenesulfonimid-N0-[(1R,2R)-2-morpholin-4-yl-cyclohexyl]-
amide [(S,R,R)-4h] by the Azirdinium Route. Same procedure as for
the synthesis of (S,S,S)-4c and (S,R,R)-4d using methanesulfonyl
chloride (28.5 μL, 0.363 mmol, 1.2 equiv), (()-trans-2-morpho-
lin-4-yl-cyclohexanol (56 mg, 0.302 mmol, 1 equiv), triethylamine
(210 μL, 1.511 mmol, 5 equiv), (S)-N-benzoyl-4-toluenesulfon-
imidamide [(S)-7, 166 mg, 0.605 mmol, 2 equiv), and water
(0.2 mL). The stirring times were 1.5 and 2 h instead of 3 and
1 h. The first chromatography (silica gel, pentane/diethylether =
2:3) afforded (S,R,R)-4h (38 mg, 0.086 mmol, 28%) as a white
solid and a mixture of (S,S,S)-4g and starting material (S)-7. A
second chromatography (silica gel, pentane/acetone = 6:1) pro-
vided pure (S,S,S)-4g (34 mg, 0.077 mmol, 25%) as a white solid.
The purities of (S,S,S)-4g and (S,R,R)-4h were equal to the
ones obtained by the nucleophilic substitution route. For analy-
tical data see the protocol of nucleophilic substitution pathway.
General Procedure for the Henry Reaction, Optimized Condi-
tions. Under an inert atmosphere of argon CuCl (5.9 mg, 0.060
mmol, 0.1 equiv) and sulfonimidamide 4 (0.060 mmol, 0.1 equiv)
were dissolved in dry CH2Cl2 (3.4 mL) and stirred overnight at
room temperature. After removal of the solvent under reduced
pressure, the resulting green solid was redissolved in EtOH
(1.2 mL). Then, MeNO2 (320 μL, 6.000 mmol, 10 equiv) and
4-methylpyrimidine (65 μL, 0.708 mmol, 1.18 equiv) were
added. After addition of the aldehyde 8 (0.600 mmol, 1 equiv)
the reaction mixture was stirred overnight at room temperature.
The solvent was removed under reduced pressure, and product 9
was purified by flash chromatography.
136.5. [R]22 -38.8 (c 0.55, CHCl3); HPLC (Chiralcel OD-H,
D
20 °C, 210 nm, 85:15 heptane/i-PrOH, 0.8 mL/min) tR = 11.7 min
(R), 14.6 min (S); the spectroscopic data are in agreement with
those reported in the literature.27
(R)-1-(2-Methoxyphenyl)-2-nitro-ethanol [(R)-9d]. Obtained
using sulfonimidamide (S,R,R)-4h (26.5 mg, 0.060 mmol) and
aldehyde 8d (81.7 mg, 0.600 mmol) according to the general
procedure. Flash chromatography (silica gel, pentane/diethy-
lether = 4:1) afforded (R)-9d (98 mg, 0.497 mmol, 83%, 95% ee)
as a yellow oil. [R]22 -50.4 (c 0.54, CHCl3); for the spectro-
D
scopic data and the determination of the enantiomeric ratio see
the preparation of (S)-9d.
(S)-1-(2-Methoxyphenyl)-2-nitro-ethanol [(S)-9d]. Obtained
using sulfonimidamide (S,S,S)-4g (26.5 mg, 0.060 mmol) and
aldehyde 8d (81.7 mg, 0.600 mmol) according to the general
procedure. Flash chromatography (silica gel, pentane/diethy-
lether = 4:1) afforded (S)-9d (74 mg, 0.375 mmol, 63%, 92% ee)
as a yellow oil. 1H NMR (CDCl3, 400 MHz) δ 3.22 (d, J1 = 6.2
Hz, 1H), 3.88 (s, 3H), 4.56 (dd, J2 = 9.1 Hz, J3 = 13.0 Hz, 1H),
4.64 (dd, J3 = 13.0 Hz, J4 = 3.3 Hz, 1H), 5.62 (m, J1 = 6.2 Hz,
J2 = 9.1 Hz, J4 = 3.3 Hz, 1H), 6.91 (d, J = 8.0 Hz, 1H), 7.01 (dt,
J1 = 7.6 Hz, J2 = 0.8 Hz, 1H), 7.33 (dt, J1 = 8.0 Hz, J2 = 1.5
Hz, 1H), 7.44 (dd, J1 = 7.6 Hz, J2 = 1.5 Hz, 1H); 13C NMR
(CDCl3, 100 MHz) δ 55.4, 67.8, 79.8, 110.4, 121.0, 125.8, 127.1,
129.7, 155.8. [R]22 þ47.8 (c 0.51, CHCl3); HPLC (Chiralcel
D
(R)-2-Nitro-1-(4-nitrophenyl)-ethanol [(R)-9a]. Obtained using
sulfonimidamide (S,R,R)-4h (26.5 mg, 0.060 mmol) and aldehyde
8a (90.7 mg, 0.600 mmol) according to the general procedure.
Flash chromatography (silica gel, pentane/diethylether = 1:1)
afforded (R)-9a (105 mg, 0.495 mmol, 82%, 88% ee) as a white
solid. 1H NMR (CDCl3, 400 MHz) δ 3.19 (bs, 1H), 4.57 (dd, J1 =
4.1 Hz, J2 = 13.7 Hz, 1H) 4.61 (dd, J2 = 13.7 Hz, J3 = 8.1 Hz,
1H), 5.61 (dd, J1 = 4.1 Hz, J3 = 8.1 Hz, 1H), 7.63 (d, J = 8.7 Hz,
2H), 8.27 (d, J= 8.7 Hz, 2H); 13CNMR(CDCl3, 100 MHz) δ70.00,
OD-H, 20 °C, 210 nm, 90:10 heptane/i-PrOH, 0.8 mL/min) tR =
13.7 min (R), 16.0 min (S); the spectroscopic data are in
agreement with those reported in the literature.27
(R)-1-(2-Methylphenyl)-2-nitro-ethanol [(R)-9e]. Obtained using
sulfonimidamide (S,R,R)-4h (26.5 mg, 0.060 mmol) and aldehyde
8e (71.5 μL, 0.600 mmol, 97%) according to the general proce-
dure. Flash chromatography (silica gel, pentane/diethylether =
4:1) afforded (R)-9e (78 mg, 0.430 mmol, 72%, 92% ee) as a
1
colorless oil. H NMR (CDCl3, 400 MHz) δ 2.39 (s, 3H), 2.76
80.6, 124.1, 126.8, 144.8, 1 qC not observed. [R]24 -30.4 (c 0.53,
(d, J1 = 3.2 Hz, 1H), 4.43 (dd, J2 = 2.6 Hz, J3 = 13.5 Hz, 1H),
4.54 (dd, J3 = 13.5 Hz, J4 = 9.8 Hz, 1H), 5.68 (m, J2 = 2.6 Hz,
J4 = 9.8 Hz, 1H), 7.16-7.22 (m, 1H), 7.23-7.30 (m, 2H),
7.49-7.55 (m, 1H); 13C NMR (CDCl3, 100 MHz) δ 19.0, 67.9,
80.2, 125.5, 126.7, 128.6, 130.8, 134.3, 136.1. [R]22D -49.5 (c 0.51,
CHCl3); HPLC (Chiralcel OD-H, 20 °C, 210 nm, 85:15 heptane/
i-PrOH, 0.8 mL/min, tR = 10.0 min (R), 14.4 min (S); the spectro-
scopic data are in agreement with those reported in the literature.27
(R)-1-Naphthalen-1-yl-2-nitro-ethanol [(R)-9f]. Obtained using
sulfonimidamide (S,R,R)-4h (26.5 mg, 0.060 mmol) and aldehyde
8f (81.5 μL, 0.600 mmol) according to the general procedure.
Flash chromatography (silica gel, pentane/diethylether = 4:1)
afforded (R)-9f (91 mg, 0.419 mmol, 70%, 93% ee) as a colorless
oil. [R]22D -24.7 (c 0.58, CHCl3); for the spectroscopic data and
the determination of the enantiomeric ratio see the preparation of
(S)-9f.
D
CHCl3); HPLC (Chiralcel OD-H, 20 °C, 210 nm, 85:15 heptane/
i-PrOH, 0.8 mL/min) tR = 19.4 min (R), 24.6 min (S); the spectro-
scopic data are in agreement with those reported in the literature.27
(R)-2-Nitro-1-phenylethanol [(R)-9b]. Obtained using sulfon-
imidamide (S,R,R)-4h (26.5 mg, 0.060 mmol) and aldehyde 8b
(61 μL, 0.600 mmol) according to the general procedure.
Flash chromatography (silica gel, pentane/diethylether =4:1)
afforded (R)-9b (79 mg, 0.473 mmol, 79%, 95% ee) as a colorless
oil. [R]22D -47.1 (c 0.51, CHCl3); for the spectroscopic data and
the determination of the enantiomeric ratio, see the preparation
of (S)-9b.
(S)-2-Nitro-1-phenylethanol [(S)-9b]. Obtained using sulfoni-
midamide (S,S,S)-4g (26.5 mg, 0.060 mmol) and aldehyde 8b
(61 μL, 0.600 mmol) according to the general procedure.
Flash chromatography (silica gel, pentane/diethylether = 4:1)
afforded (S)-9b (47 mg, 0.281 mmol, 47%, 92% ee) as a colorless
(S)-1-Naphthalen-1-yl-2-nitro-ethanol [(S)-9f]. Obtained using
sulfonimidamide (S,S,S)-4g (26.5 mg, 0.060 mmol) and aldehyde
8f (81.5 μL, 0.600 mmol) according to the general procedure.
Flash-chromatography (silica gel, pentane/diethylether =4:1)
afforded (S)-9f (62 mg, 0.285 mmol, 48%, 88% ee) as a color-
less oil. 1H NMR (CDCl3, 400 MHz) δ 3.05 (bs, 1H), 4.62 (dd,
1
oil. H NMR (CDCl3, 300 MHz) δ 2.97 (d, J1 = 3.3 Hz, 1H,
OH), 4.50 (dd, J2 = 3.3 Hz, J3 = 13.3 Hz, 1H), 4.60 (dd, J3 =
13.3 Hz, J4 = 9.4 Hz, 1H), 5.44 (td, J1 = J2 = 3.3 Hz, J4 = 9.4
Hz, 1H), 7.32-7.45 (m, 5H); 13C NMR (CDCl3, 75 MHz) δ 71.0,
81.2, 125.9, 128.9, 129.0, 138.1. [R]23 þ44.5 (c 0.52, CHCl3);
D
J. Org. Chem. Vol. 75, No. 10, 2010 3309

Steurer and Bolm
JOCArticle
J1 = 8.4 Hz, J2 = 13.5 Hz, 1H) 4.67 (dd, J2 = 13.5 Hz, J3 = 3.8
Hz, 1H), 6.19-6.25 (m, 1H), 7.48-7.62 (m, 3H), 7.72-7.77 (m,
1H), 7.85 (d, J = 8.3 Hz, 1H), 7.89-7.93 (m, 1H), 8.02 (d, J = 8.3
Hz, 1H); 13C NMR (CDCl3, 100 MHz) δ 68.2, 80.7, 121.7, 123.7,
125.4, 126.0, 126.9, 129.2, 129.2, 129.4, 133.4, 133.6. [R]21D þ24.5
(c 0.53, CHCl3); HPLC (Chiralcel OD-H, 20 °C, 210 nm, 85:15
heptane/i-PrOH, 0.8mL/min, tR = 15.3 min (R), 21.4 min (S); the
spectroscopic data are in agreement with those reported in the
literature.27
(DFG) within the SPP 1179 (“Organocatalysis”) for finan-
cial support, and we thank Dr. Ingo Schiffers for very helpful
discussions and the synthesis of enantiopure trans-cyclohex-
anediamines and sulfonamide 10. We also appreciate the
help of Pascal Gross in synthesizing various compounds and
^
are grateful to Prof. Dr. Emmanuel Lacote, Paris for provid-
ing information on the synthesis of sulfonimidamides.
1
Supporting Information Available: Copies of H and 13C
Acknowledgment. We are grateful to the Fonds der Che-
mischen Industrie and the Deutsche Forschungsgemeinschaft
NMR spectra of all products. This material is available free of
charge via the Internet at http://pubs.acs.org.
3310 J. Org. Chem. Vol. 75, No. 10, 2010