The search for benchrotrenes and ferrocenes containing a chiral sulfoximido group: Preparation and structural properties

Article abstract of DOI:10.1055/s-1999-3518

Syntheses of chiral benchrotrene and ferrocene complexes bearing N- protected sulfonimidoyl moieties are reported. They are obtained by metal- catalyzed imination reactions starting from enantiopure sulfoxides. An X-ray structure analysis was carried out for one of the novel complexes confirming the stereospecificity of the imination process.

Full text of DOI:10.1055/s-1999-3518

FEATURE ARTICLE
1251
The Search for Benchrotrenes and Ferrocenes Containing a Chiral
Sulfoximido Group: Preparation and Structural Properties
Carsten Bolm,* Kilian Muñiz, Núria Aguilar, Martin Kesselgruber, Gerhard Raabe
Institut für Organische Chemie der RWTH Aachen, Professor-Pirlet-Str.1, D-52074 Aachen, Germany
Fax + 49(241)8888391; E-mail: carsten.bolm@oc.rwth-aachen.de
Received 12 April 1999
Dedicated to Professor Dr. Ch. Elschenbroich (Marburg) on the occasion of his 60th birthday
attempts to achieve this transformation including the use
of hexacarbonyl chromium(0), tricarbonyl trisacetoni-
trilochromium(0) and tricarbonyl(η -naphthalene)chrom-
Abstract: Syntheses of chiral benchrotrene and ferrocene complex-
es bearing N-protected sulfonimidoyl moieties are reported. They
are obtained by metal-catalyzed imination reactions starting from
6
enantiopure sulfoxides. An X-ray structure analysis was carried out ium(0) (Kündig’s reagent) as Cr(CO)
for one of the novel complexes confirming the stereospecificity of resulting from complexation were ever isolated. Only in a
the imination process.
single case, when the thermal complexation of N,S-dime-
Key words: sulfoximines, imination of sulfoxides, metal catalysis, thyl S-phenyl sulfoximine and Cr(CO) was stopped after
source, no products
3
6
chromium transition metal complexes, iron transition metal com-
plexes
a reaction time of 7 hours, traces of the expected product
could be detected in the crude proton NMR spectrum.
Similar observations have been reported by Gibson (née
Thomas) who found that the direct complexation of alkyl-
sulfinyl arenes in the presence of the mentioned tricarbo-
nylchromium(0) sources gave the desired chromium
Introduction
4
complexes in yields of only 0–4%. Here, the respective
The synthesis of chiral ferrocene and benchrotrene com-
plexes is of ongoing interest in organometallic chemistry
because these compounds have found various applica-
tions in organic synthesis, catalytic processes and material
6
tricarbonyl(alkylsulfanyl-η -arene)chromium(0)
com-
plexes had to be generated from the alkylsulfanyl precur-
4
sors by oxidation with dimethyldioxirane or Kagan’s
5
1
modified Sharpless reagent. Interestingly, the corre-
sciences. A few years ago, we initiated a program that fo-
sponding sulfonyl complexes could be obtained by the
cussed on the use of bidentate sulfoximines as chiral
ligands for metal complexes, and we began to investigate
usual complexation procedure without any difficulty.6
their applications in several asymmetric catalytic transfor- After these unsuccessful attempts of direct sulfoximine
2
,3
mations.
complexation we decided to change strategy and to focus
on iminations of known alkylsulfinyl-substituted arene
chromium complexes. In particular, our attention was
turned towards two recent procedures for copper(I)-cata-
In the course of these studies we became aware that sulf-
oximines containing an organometallic π-complex as
backbone were unknown and thus decided to investigate
the preparation of such compounds. For benchrotrenes
and ferrocenes of such type, the respective target struc-
tures A and B are depicted in Figure 1. In this feature ar-
ticle we report on our recent results in this area.
7
lyzed imination reactions of aromatic sulfides and sul-
8
foxides. However, employing the conditions described
for the conversion of sulfoxides into sulfoximines by use
6
of copper(I) triflate, imination of tricarbonyl(methyl η -
5
phenyl sulfoxide)chromium(0) (1) led to green and
cloudy reaction mixtures within seconds after the addition
O
of the first portion of N-(p-toluenesulfonyl)iminophenyl-
λ -iodane indicating an oxidative decomposition of the
starting material by the hypervalent iodine. In accordance
with this assumption, the product, which was isolated
from this reaction after the usual workup, was identified
as the uncomplexed sulfoximine 2 (Scheme 1).
NR'
R
O
S
3
S
NR'
Fe
Cr
CO)3
R
(
A
B
Figure 1
O
NTos
Me
O
CuOTf, PhI=NTos
CH3CN, rt
S
S
Synthesis of Benchrotrenyl Sulfoximines
Me
Cr
CO)3
(
6
Tricarbonyl(η -arene)chromium(0) complexes became
our prime targets because complexes like A were expect-
ed to be accessible from direct complexation of the re-
spective aryl sulfoximines. However, despite numerous
1
2
Scheme 1
Synthesis 1999, No. 7, 1251–1260 ISSN 0039-7881 © Thieme Stuttgart · New York

1
252
C. Bolm et al.
FEATURE ARTICLE
Biographical Sketches
Carsten Bolm was born in Sharpless, he worked in Maier-Leibnitz prize, the
Braunschweig in 1960. He Basel with Prof. Giese to ADUC-Jahrespreis for ha-
studied chemistry at the uni- obtain his habilitation. In bilitands, the annual prize
versities in Braunschweig 1993 he became Professor for Chemistry of the Akade-
and Madison, Wisconsin, of Organic Chemistry at the mie der Wissenschaften zu
and obtained his doctorate University of Marburg, and Göttingen, the Otto-Klung
in 1987 under the guidance since 1996 he is full profes- prize, and the Otto-Bayer
of Prof. Reetz in Marburg. sor of Organic Chemistry at award.
After postdoctoral studies at the RWTH Aachen. His
MIT, Cambridge, with Prof. awards include the Heinz-
Kilian Muñiz was born in worked on his PhD in the sis of enantiomerically pure
Hildesheim in 1970. He group of Prof. Bolm at the complexes and their behav-
studied chemistry at the RWTH Aachen (Germany). iour in asymmetric transfor-
Universität Hannover (Ger- Currently, he is a postdoc- mations.
many), at Imperial College, toral fellow with Prof. Noy-
London (UK) and at the ori at Nagoya University
Universidad de Oviedo (Japan). His research inter-
(
Spain) to obtain his Diplo- ests are in the area of orga-
ma in Chemistry in 1996. nometallic chemistry with
From 1996 to 1998 he special focus on the synthe-
Núria Aguilar was born in where she focussed on the tion at the Organic Depart-
Barcelona in 1971. She stereoselective synthesis of ment of the Universitat de
studied Chemistry at Uni- chiral amino alcohols. Dur- Barcelona.
versitat
de
Barcelona ing fall 1998 she joined the
(
Spain) and received her group of Prof. Bolm at the
BSc and MSc degrees from RWTH Aachen (Germany)
this university in 1994 and as an exchange student. She
1
1
995, respectively. Since was awarded her PhD earli-
995 she has been working er this year and is currently
in the group of Prof. Pericàs holding an academic posi-
Martin Kesselgruber was research group of Prof.
born in Mistelbach (Austria) Bolm on the preparation of
in 1974. He studied Chemis- ferrocenyl sulfoximines and
try at the University of their application in asym-
Technology Vienna (Aus- metric catalysis.
tria) and received his MSc
degree in 1998 under the
guidance of Prof. Jordis.
Currently he is carrying out
his PhD studies within the
Gerhard Raabe was born (USA) he worked on the at the RWTH Aachen.
in Obrighoven (Germany) matrix isolation of highly Working in the field of the-
in 1950. He studied chemis- reactive silicon compounds. oretical organic solid state
try and received his degrees After additional postdoctor- chemistry he finished his
from the RWTH Aachen al work with Prof. Fleis- Habilitation in 1998. His re-
(
Diploma 1980, Dr.rer.nat. chhauer he left for a brief search interests concern var-
1
984, both with Prof. Fleis- sojourn in industry (1987/ ious aspects of theoretical
chhauer). During a postdoc- 1988). Since 1989 he is in chemistry especially the
toral stay (1984/1985) with charge of the X-ray struc- structure of and the bonding
Prof. Michl at the Universi- ture division of the Depart- in organic molecular crys-
ty of Utah in Salt Lake City ment of Organic Chemistry tals.
Synthesis 1999, No. 7, 1251–1260 ISSN 0039-7881 © Thieme Stuttgart · New York

FEATURE ARTICLE
The Search for Benchrotrenes and Ferrocenes Containing a Chiral Sulfoximido Group
1253
Imination of enantiomerically enriched complex 1 was fi- of (R)-6 gave access to (R)-configurated ferrocenyl meth-
nally achieved following a recent protocol by Bach and yl sulfoxide (78% yield, 93% ee).
Körber who recommended the use of iron(II) chloride and
The novel ferrocenyl (2-methoxynaphthyl) sulfoxide (5e)
9
t-butyloxycarbonyl azide. Under modified reaction con-
was obtained in a similar fashion from the diastereomeri-
ditions sulfonimidoyl complex 3 was obtained in 67%
chemical yield (Scheme 2).
15
cally pure sulfinyl 7.
5
5
a: R = p-Tol,
b: R = t-Bu,
O
O
O
Ot-Bu
N
5c: R = Ph,
5d: R = Me,
S
R
S
FeCl2 (0.5 eq),
S
Me
O
5e: R =
Me
Fe
t-BuOC(O)N3,
CH2Cl2 (57%)
Cr
Cr
(CO)3
OMe
(CO)3
1
3
O
O
S
NH
Me
O
O
air, TFA,
CH2Cl2
O
O
Me
O
S
O
S
OMe
O
O
4
(
S)-6
7
Scheme 2
As expected, in the proton NMR spectrum the diaste-
reotopic ortho-hydrogens can clearly be identified by
their significant downfield shifts to δ = 5.80 and 4.98.
This is in agreement with the data of the parent sulfoxide
complexes for which comparable shifts were observed.4
Synthesis of Ferrocenyl Sulfoximines
At first, the synthesis of ferrocenylsulfoximines was at-
tempted employing the well-studied O-mesitylensulf-
onylhydroxylamine (MSH) reagent,16 but this procedure
did not lead to the formation of any sulfoximine from the
corresponding sulfoxide, and only starting material was
isolated from the reaction mixture. Consequently, atten-
tion was again turned towards the mentioned copper tri-
,10
In order to determine the stereochemical path of the im-
ination of 2, complex 3 was transformed into known S-
methyl S-phenylsulfoximine (4) by one-pot treatment
with iodine/air and TFA in order to remove both the chro-
mium moiety and the Boc group simultaneously. GC-
analysis of 4 revealed that the imination had been ste-
reospecifically indeed.
8
flate catalyzed imination since it was assumed that in the
case of ferrocenyl sulfoxides no oxidative decomposition
should occur. Thus, ferrocene 5a was submitted to imina-
tion, but under literature conditions the conversion re-
mained very low. However, by changing the copper salt to
Synthesis of Ferrocenyl Sulfoxides
Cu(I)PF and by careful optimization of the reaction con-
6
ditions, an increase in chemical yield was achieved. Rep-
resentative data are summarized in Table 1.
Because direct complexation of sulfoximido precursors is
not feasible in the case of ferrocenyl sulfoximines, sulfox-
ide imination occurred as the route of choice. Enantiopure
ferrocenes 5a–d were synthesized according to literature
protocols from Kagan, Riant and co-workers employing
either Kagan’s asymmetric oxidation of the correspond-
O
O
NSO p-Tol
2
S
S
p-Tol
copper(I) salt,
p-Tol
1
1
ing ferrocenyl sulfides or reaction of lithio ferrocene
with the respective diastereomerically pure sulfinyl pre-
Fe
Fe
PhI=NSO2p-Tol
1
2
cursors. Application of an alternative system for enan-
tioselective sulfide oxidation as recently reported from
1
3
5a
8a
our laboratories gave ferrocenyl methyl sulfoxide (5d)
with only 39% ee. A very convenient route towards enan-
tiopure 5d was finally developed starting from the two
methylsulfinates of diacetone-D-glucose which are readi-
Scheme 3
1
4
ly accessible in diastereomerically pure form. Thus, re- Subsequently, ferrocenyl sulfoxides 5a–d were submitted
action of 6 having S-configuration at sulfur with in situ- to imination under the optimized reaction conditions us-
generated ferrocenyl lithium yielded 1d with 90% enan- ing 20 mol% of Cu(I)PF as catalyst and N-(p-toluene-
6
tiomeric excess in 65% chemical yield. Consequently, use
Synthesis 1999, No. 7, 1251–1260 ISSN 0039-7881 © Thieme Stuttgart · New York

1
254
C. Bolm et al.
FEATURE ARTICLE
3
sulfonyl)iminophenyl-λ -iodane as nitrene source in
acetonitrile (Table 2).
O
O
NSO p-Tol
2
Cu(I)PF6
S
S
R
R
(20 mol-%),
Fe
Fe
PhI=NSO2p-Tol,
CH3CN
5a-d
8a-d
Scheme 4
a
Table 1 Copper(I)-catalyzed imination of ferrocenyl sulfoxide 5a
Entry
Metal catalyst Solvent
ReactionTime Chemical
[h]
(
mol %)
Yield [%]c
a
d
1
2
3
4
CuOTf (5)
CuPF6b (5)
Toluene
Toluene
50
47
46
49
8
d
10
d
CuPF (5)
CuPF (20)
CH CN
20
6
3
CH CN
58
6
3
a
CuOTf(C H )
.
6
6 0.5
b
c
d
CuPF (CH CN) .
6
3
4
Isolated after column chromatography and/or recrystallization.
As determined from the H NMR spectrum of the crude reaction
1
mixture.
Figure 2 Selected bond lengths (Å) and angles (°) for 8b: S1–C5
1
1
1
.734(7), S1–O1 1.443(4), S1–C18 1.825(7), S1–N 1.542(5), N–S2
.602(5), O1–S1–C5 109.7(3), O1–S1–C18 108.0(3), C5–S1–C18
05.4(3), O1–S1–N 120.8(2).
Table 2 Copper(I)-catalyzed imination of ferrocenyl sulfoxides
5
a–d
Entry Ferrocene
Rest R
Product Reaction Chemical
Time [h] Yield [%]
b
It is interesting to compare the structural features of this
compound to those of related ferrocenyl sulfoxides.
Apparently, the geometry around the sulfur atom and the
bond lengths between the sulfur and the two attached car-
bon atoms are not altered significantly by the introduction
of the imido moiety.
1
2
3
4
5a
5b
5c
5d
p-Tolyl
t-Butyl
Phenyl
Methyl
8a
8b
8c
8d
49
44
39
53
53
46
51
43
12b,18
a
CuPF (CH CN) .
Isolated after column chromatography and/or recrystallization.
6
3
4
b
Moreover, as for all new compounds 8a–d the proton
NMR spectrum of 8b contains two signals for either
ortho-hydrogen on the substituted ferrocene ring display-
ing the diastereotopicity of these hydrogens. While the
All ferrocenyl sulfoximines prepared by this modified im-
ination procedure are air-stable, orange to brownish sol-
ids, which can easily be separated from unreacted
ferrocenyl sulfoxides by column chromatography. No fer-
rocene-containing byproducts were detected and chemical
yields are nearly quantitative based on the amounts of re-
covered starting material. On the other hand, neither a
higher catalyst loading nor carrying out the reaction at
higher reaction temperature led to an improvement in con-
version.
chemical shift of δ = 4.77 for the pro-S -hydrogen is only
p
slightly changed relative to the δ = 4.69 in the parent fer-
rocenyl sulfoxide, the second ortho-hydrogen experiences
a significant downfield shift from δ = 4.35 in 5b to δ =
4
.59 in 8b. Such a displacement can be rationalized by the
proximity of this hydrogen to the newly introduced imido
group.
The imination of ferrocenyl sulfoxides can also be carried
The solid state structure of complex 8b is shown in Figure
3
out employing N-(p-nitrophenylsulfonyl)iminophenyl-λ -
1
7
2
. In 8b, the absolute configuration at sulfur S1 was de-
iodane as the nitrogen source. So far, examples for the use
termined to be S, which is in agreement with a stereospe-
of this hypervalent iodane in catalytic transformation are
cific imination under retention of configuration as already
19,20
still rare,
and to date none has been reported for the
8
described for the original catalytic system.
conversion of sulfides or sulfoxides.
Synthesis 1999, No. 7, 1251–1260 ISSN 0039-7881 © Thieme Stuttgart · New York

FEATURE ARTICLE
The Search for Benchrotrenes and Ferrocenes Containing a Chiral Sulfoximido Group
1255
Table 3 Copper(I)-catalyzed imination of ferrocenyl sulfoxides
a–e
O
5
SnBu3
SnBu3
S
p-Tol
Entry Ferrocene Rest R
Product Reaction Chemical
Time [h] Yield [%]
Fe
b
Fe
1
2
3
4
5
5a
5b
5c
5d
5e
p-Tolyl
t-Butyl
Phenyla
Methyl
9a
9b
9c
9d
41
55
48
64
61
69
62
66
68
74
SnBu3
10
11
2-Methoxy- 9e
O
naphthyl
N-SO2p-NO2Ph
p-Tol
S
a
Racemic material was used.
Isolated after column chromatography and/or recrystallization.
Cu(I)PF6
(20 mol-%),
b
Fe
PhI=NSO2p-NO2Ph,
CH3CN (64%)
SnBu3
The results for the synthesis of the N-nosyl-protected fer-
rocenylsulfoximines are given in Table 3.
12
Scheme 6
O
O
NSO2p-NO2Ph
R
Cu(I)PF6
S
S
R
Unfortunately, compound 12 proved unstable during puri-
fication. Even when stored under argon partial decompo-
sition occurred.
(20 mol-%),
Fe
Fe
PhI=NSO2p-NO2Ph,
CH3CN
In summary, we have described the syntheses of the first
enantiopure sulfoximines bearing benchrotrenyl and fer-
rocenyl backbones. We are currently investigating the re-
moval of the N-protecting groups,25 the incorporation of
the ferrocenyl sulfoximido moiety into catalyst systems,2
and we try to generate planar chiral derivatives starting
from the N-protected ferrocenyl sulfoximines.2
5
a-e
9a-e
Scheme 5
6,27
It is notable that this process of imidonosylation gives
higher yields as in comparable cases where the tosyl pre-
cursor is employed. Such behavior has already been ob-
served by Andersson in Cu-catalyzed aziridinations of
All manipulations except workup and purification steps were per-
formed in oven-dried glass ware under Ar using common Schlenk
techniques. Chromium hexacarbonyl, ferrocene, butyllithium and
1
9a
alkenes.
Again, the product ferrocenes 9a–e are air-stable, light tributyltin chloride were obtained from Merck-Schuchardt and used
yellow to orange solids that are generated without forma- as received. Copper(I) triflate and copper(I) hexafluorophosphate
were purchased from Aldrich and stored under Ar. THF, hexane,
tion of ferrocene-containing byproducts. Their spectro-
dibutyl ether and toluene were distilled from sodium/benzophenone
scopic properties are similar to those of the tosyl
ketyl radical under Ar. CH Cl was distilled from CaH under Ar.
2
2
2
derivatives including the distinct diastereotopicity of the
ortho-hydrogens as clearly observed in the proton NMR
spectra. For example, significant downfield shifts to δ =
All other solvents were reagent grade and used as received. Sulfox-
ide complexes 1 and 5a–c were obtained following literature proto-
5
,11,12
cols.
(R)-
and
(S)-1,2:5,6-di-O-isopropylidene-α-D-
14
4
.79 and δ = 4.62 for the two ortho-protons of complex 9b glucofuranosylmethanesulfinate,
(–)-menthyl-(S)-(2-meth-
1
5
24
were detected.
oxynaphthyl)sulfinate, (–)-menthyl-(S)-(p-tolyl)sulfinate, N-(p-
toluenesulfonyl)iminophenyl-λ -iodane,
nyl)iminophenyl-λ -iodane and t-butyloxycarbonyl azide were
3
30
N-(p-nitrophenylsulfo-
Next, we wondered about a 1,1’-substitution pattern on
the ferrocene. Such functionalization should allow future
incorporation of ferrocenyl sulfoximines into dendritic
structures or polymers via the “lower” cyclopentadienyl
3
30
9
synthesized according to literature protocols.
If not stated otherwise, "standard workup" refers to quenching the
mixture with distilled water, followed by extraction with CH Cl
2
2
2
1,22
ring.
A tributyltin moiety was considered suitable for and washing of the organic layer with brine and water followed by
this purpose and thus, (1’-tributyltinferrocenyl)sulfox- drying of the combined organic phases with anhyd MgSO4.
imine (11) was synthesized by transmetalation of 1,1’-
1H NMR spectra were recorded at 300 MHz and chemical shifts are
bis(tributyltin)ferrocene (10) with 1.1 equiv. of reported in ppm with internal referencing to TMS. Splitting pattern
2
3
butyllithium followed by reaction of the resulting mono- are designated as s (singlet), d (doublet), t (triplet), m (multiplet).
1
3
C NMR spectra were recorded at 75 MHz and chemical shifts are
lithiated complex with (–)-menthyl-(S)-p-tolyl sulfinate
(
lent yield. Imination of this compound employing the con-
ditions described above furnished sulfoximine 12 in the
good chemical yield of 64% which is comparable to that
of the 1’-unsubstituted complex 9a.
Andersen’s reagent12c, 24) to give sulfoxide 11 in excel-
reported in ppm with internal referencing to TMS. Generally, spec-
tra were recorded in CDCl ; other solvents were used as indicated.
Optical rotations were measured at r.t. Elemental analyses and
HRMS were carried out at the Institutes of Organic and Inorganic
Chemistry at RWTH Aachen, respectively. All new syntheses were
3
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1
256
C. Bolm et al.
FEATURE ARTICLE
repeated at least twice in order to ensure reproduceability. Given
yields are average values.
mg, 0.1 mmol) in 2.5 mL of freshly distilled THF under argon. The
deep red solution was stirred for 5 min at r.t. before distilled H O
2
(27 µL, 1.5 mmol) was added. After stirring for 55 min, ferrocenyl
S-Methyl-S-phenyl-N-p-tolylsulfonylsulfoximine (2)
A solution of (S)-tricarbonyl[methyl η -phenyl sulfoxide]chrom-
ium(0) (1) (106 mg, 0.384 mmol) and copper(I) triflate (28.5 mg,
methyl sulfide (100 mg, 0.5 mmol) was added and stirring was con-
tinued for 30 min before the mixture was cooled to 0°C. At this tem-
6
perature, a solution of TBHP (70% in H O, 75 µL, 0.55 mmol) was
2
added and the mixture was stirred for 22.5 h before it was submitted
to standard workup. The crude product was purified by column
chromatography [silica gel, EtOAc/hexanes (70/30), then EtOAc,
then THF] to yield the title compound in form of a dark highly vis-
cous oil (94.0 mg, 0. 435 mmol, 87% yield).
0
.077 mmol) in freshly distilled MeCN (10 mL) was treated por-
3
tionwise with N-(p-toluenesulfonyl)iminophenyl-λ -iodane (172
mg, 0.461 mmol). The mixture was stirred for 2 days and the
progress was monitored by tlc which showed complete consump-
tion of starting material. Standard workup and purification by col-
umn chromatography (silica gel, Et O) gave the title compound
2
(69.6 mg, 0.273 mmol, 71% yield) as a yellowish solid.
Procedure B
1H NMR: δ = 2.37 (s, 3H); 3.40 (s, 3H); 7.22–7.29 (m, 2H); 7.55–
A solution of ferrocenyl tributylstannane (663 mg, 1.395 mmol) in
freshly distilled THF (20 mL) at –78°C was treated dropwise with
BuLi (0.97 mL, 1.6M in hexane, 1.55 mmol). The mixture was
stirred for 45 min and then transferred dropwise via cannula into a
second solution of (S)-6 (500 mg, 1.55 mmol) in freshly distilled
THF (20 mL) at –78°C. The resulting yellow solution was main-
tained at –78°C for 10 min before quenching. Standard workup and
column chromatography [silica gel, hexanes/i-PrOH (90/10)] af-
forded the title complex (250 mg, 1.01 mmol, 65.3% yield) in form
of an orange solid. HPLC revealed an enantiomeric excess of 90%.
The product could be recrystallized from hexane at r.t. to yield the
title complex with 96% ee.
7
2
.58 (m, 2H); 7.65–7.69 (m, 1H); 7.81–7.83 (m, 2H); 7.96–7.98 (m,
H).
13C NMR: δ = 21.60; 46.60; 126.68; 127.51; 129.38; 129.80;
1
34.51; 138.26; 140.71; 142.98.
6
(
S)-Tricarbonyl[η -N-tert-butyloxycarbonyl-S-methyl-S-phen-
ylsulfoximine]chromium(0) (3)
In a well-dried Schlenk tube under Ar, 1 (200 mg, 0.72 mmol) and
FeCl2 (46 mg, 0.36 mmol) were dissolved in freshly distilled
CH Cl (10 mL) and stirred at r.t. t-Butyloxycarbonyl azide (115
2
2
mg, 0.796 mmol) was added dropwise and the mixture was stirred
at r.t. for 29 h while the progress was monitored by tlc. Standard
workup and column chromatography [silicagel, Et O, then Et O/
1H NMR: δ = 2.76 (s, 3H); 4.35 (s, 5H); 4.35–4.49 (m, 3H); 4.69–
4
.72 (m, 1H).
2
2
13C NMR: δ = 42.34; 66.06; 66.36; 69.85; 70.09; 70.16; 93.01.
MeOH (70/30)] gave a first fraction containing the title complex
and a second containing unreacted starting material. After removal
of the solvent, the title complex was obtained in form of a yellow
solid [189 mg, 0. 483 mmol, 67% yield (98% based on recovered
starting material)]. In order to avoid decomposition, the solid prod-
uct was stored under argon at –24°C.
The enantiomeric excess of the respective product samples was de-
termined by chiral HPLC on solid phase employing a Daicel
CHIRACEL OD-H column. Eluent: hexane/i-PrOH (97/3); flow
–1
rate: 0.4 mLmin ; retention times: 127.5 (S-enantiomer), 137.5 (R-
enantiomer).
[
α] = –33 (c = 0.35, CH Cl ).
D 2 2
1
(S)-Ferrocenyl (2-Methoxy)naphthyl Sulfoxide (5e)
H NMR (C D ): δ = 1.07 (s, 9H); 2.75 (s, 3H); 3.88–3.94 (m, 2H);
6
6
A solution of ferrocenyl tributylstannane (760 mg, 1.60 mmol) in
freshly distilled THF (10 mL) at –78°C was treated dropwise with
BuLi (1.00 ml, 1.60 mmol, 1.6 M solution in hexane). The mixture
was stirred for 45 min and then transferred dropwise via cannula
into a second solution of (–)-menthyl-(S)-(2-methoxynaphthyl)sul-
finate (550 mg, 1.52 mmol) in freshly distilled THF (20 mL) at –
4
.34–4.38 (m, 1H); 4.97–4.99 (m, 1H); 5.79–5.81 (m, 1H).
1
3
C NMR (C D ): δ = 14.98; 27.54; 42.86; 85.54; 85.68; 91.33;
6
6
9
4.44; 94.60; 107.88; 229.46.
MS (EI, 70 eV): m/z (%) = 335 (M+ – 2 CO, 4), (307 M+ – 3 CO, 7),
2
5
51 (7), 200 (25), 182 (100), 156 (20), 124 (115), 94 (35), 77 (21),
7 (33).
7
8°C. The resulting yellow solution was maintained at –78°C for 2
h before warmed to –40°C over a period of 4 h. Standard workup
~
IR (KBr): n = 3019, 2978, 1984, 1966, 1920, 1895, 1659, 1367,
1
and column chromatography [silica gel, Et O/hexanes (70/30)] af-
–
1
2
307, 1279, 756 cm .
forded the title complex (512 mg, 1.31 mmol, 86% yield) in form of
a yellow solid.
(S)-S-Methyl-S-phenylsulfoximine (4)
[
α] = +297 (c = 0.3, CH Cl ).
A solution of 3 (160 mg, 0.41 mmol) in CH Cl (10 mL)was treated
D 2 2
2
2
1H NMR: δ = 4.00 (s, 3H); 4.14–4.19 (m, 2H); 4.32 (s, 5H); 4.33–
4.37 (m, 1H); 4.98–5.00 (m, 1H); 7.20 (d, J = 9.1 Hz, 1H); 7.32–
7.39 (m, 1H); 7.46–7.53 (m, 1H); 7.76 (dd, J = 0.8, 8.3 Hz, 1H);
7.88 (d, J = 9.1 Hz, 1H); 8.98 (d, J = 8.8 Hz, 1H).
with trifluoroacetic acid (1.0 mL) and exposed to air. After 4 hours,
a small amount of iodine was added directly and the mixture was
stirred for a further 28 h. The crude mixture was filtered through a
pad of Kieselgur and diluted with H O. Subsequent acid/base ex-
2
traction afforded a colourless solid (29.3 mg, 0.189 mmol, 46%
yield).
1H NMR: δ = 2.75 (s, 3H); 7.46–7.57 (m, 3H); 7.62–7.67 (m, 2H).
13C NMR: δ = 56.57; 67.24; 67.71; 69.21; 69.46; 69.56; 91.76;
1
12.58; 123.71; 124.06; 127.18; 128.01; 128.29; 129.90; 131.35;
133.74; 155.57.
MS (EI, 70 eV): m/z (%) = 392 (M+2, 8), 392 (M+1, 25), 390 (M+,
100), 324 (37), 295 (25), 233 (28), 121 (29).
The enantiomeric excess of the product sample derived from 1 (ca.
5
9
0% ee ) was 89% and was determined by GC on chiral phase em-
ploying a Lipodex E column (50 m ¥ 0.25 mm). Oven temperature:
~
IR (KBr): n = 1617, 1589, 1504, 1464, 1427, 1333, 1270, 1248,
1
60°C (isothermic); head column pressure: 75 kPa N ; retention
2
–1
1
150, 1046, 1021, 816, 751 cm .
times: 54.15 min (S-enantiomer), 50.47 min (R-enantiomer).
Anal. C H FeO S (390.27): calcd C, 64.63; H, 4.65; found C,
2
1
18
2
6
4.63; H, 4.80.
(S)-S-Ferrocenyl S-Methyl Sulfoxide (5c)
Procedure A
Titanium tetraisopropoxide (15 µL; 0.05 mmol) was added to a so-
lution of (S,S)-4,4’-bis(3-hydroxy-estra-1,3,5(10),6,8-pentane) (50
Synthesis 1999, No. 7, 1251–1260 ISSN 0039-7881 © Thieme Stuttgart · New York

FEATURE ARTICLE
The Search for Benchrotrenes and Ferrocenes Containing a Chiral Sulfoximido Group
1257
General Procedure for the Imination of Ferrocenyl Sulfoxides
a–d by Means of Hypervalent N-(P-Toluenesulfonyl)imi-
nophenyl-λ -iodane
(S)-S-Ferrocenyl-S-phenyl-N-p-tolylsulfonysulfoximine (8c)
5
Following the general procedure detailed above, (S)-S-ferrocenyl-
S-phenyl sulfoxide 5c (85 mg, 0.274 mmol) was reacted with N-(p-
3
3
The ferrocenyl sulfoxide and the copper catalyst were placed in a
dry schlenk flask under Ar and were dissolved in freshly distilled
MeCN (10 mL per mmol of substrate). The solution was stirred at
toluenesulfonyl)iminophenyl-λ -iodane (113 mg, 0.303 mmol) in
the presence of copper(I) hexafluorophosphate (20 mg, 0.054
mmol). Purification by column chromatography [silica gel, CH Cl /
2
2
3
r.t. while N-(p-toluenesulfonyl)iminophenyl-λ -iodane (1.2 mmol
acetone (95/5)] yielded the title complex (67 mg, 0.140 mmol, 51%
yield) in form of an orange to brownish solid.
per 1 mmol of substrate) was added in small portions over a period
of 2 h. The mixture was then sealed and stirred at r.t. Conversion
was monitored by tlc and after 48–60 h the mixture was filtered
through a G3 frit followed by standard workup.
[
α] = –71 (c = 0.1, CH Cl ).
D 2 2
1H NMR: δ = 2.37 (s, 3H); 4.30 (s, 5H); 4.38–4.40(m, 1H); 4.44–
4
2
.46 (m, 1H); 4.52–4.54 (m, 1H); 4.92–4.93 (m, 1H); 7.21–7.25 (m,
H); 7.42–7.47 (m, 2H); 7.50–7.55 (m, 1H); 7.86–7.90 (m, 2H).
The crude mixtures were purified as stated below.
13C NMR: δ = 21.65; 68.05; 70.61; 71.21; 71.90; 90.60; 126.71;
(
S)-N-p-Tolylsulfonyl-S-p-tolyl-S-ferrocenylsulfoximine (8a)
1
27.18; 129.32; 133.21; 141.55; 142.61.
Following the general procedure detailed above, (S)-S-ferrocenyl S-
p-tolyl sulfoxide 5a (549 mg, 1.695 mmol) was reacted with N-(p-
toluenesulfonyl)iminophenyl-λ -iodane (697 mg, 1.87 mmol) in the
+
MS (EI, 70 eV): m/z (%) = 479 (M , 100), 414 (73), 310 (9), 121
3
(14), 91 (14), 66 (29).
presence of copper(I) hexafluorophosphate (126 mg, 0.339 mmol).
Purification by column chromatography (silica gel, CH Cl ) yielded
the title complex (443 mg, 0.899 mmol, 53% yield) in form of an
~
IR (KBr): n = 1319, 1242, 1152, 1090, 1060, 1030, 805, 757, 524
2
2
–1
cm .
Anal. C H FeNO S (479.03): calcd C, 57.62; H, 4.42; N, 2.92;
orange solid. Recrystallization from hexane/Et O afforded a light
23 21
3 2
2
found C, 57.38; H, 4.54; N, 2.99.
brown solid.
[
α] = –245 (c = 0.4, CH Cl ).
D 2 2
(
S)-S-Ferrocenyl-S-methyl-N-p-tolylsulfonylsulfoximine (8d)
1H NMR: δ = 2.37 (s, 3H); 2.38 (s, 3H); 4.29 (s, 5H); 4.37–4.39 (m,
Following the general procedure detailed above, (S)-ferrocenyl me-
thyl sulfoxide 5d (265 mg, 1.07 mmol) was reacted with N-(p-tolu-
enesulfonyl)iminophenyl-λ -iodane (439 mg, 1.18 mmol) in the
presence of copper(I) hexafluorophosphate (79 mg, 0.213 mmol).
Purification by column chromatography [silica gel, CH Cl /acetone
1
7
1
H); 4.41–4.45 (m, 1H); 4.50–4.53 (m, 1H); 4.90–4.92 (m, 1H);
.23–7.26 (m, 4H); 7.75–7.79 (m, 2H); 7.88–7.91 (m, 2H).
3
H NMR (C D ): δ = 1.48 (s, 3H); 1.55 (s, 3H); 3.42–3.44 (m, 1H);
6
6
3
1
8
.52–3.55 (m, 1H); 3.83 (s, 3H); 4.05–4.06 (m, 1H); 4.51–4.53 (m,
H); 6.41 (d, J = 8.3 Hz, 2H); 6.54 (d, J = 8.2 Hz, 2H); 7.74 (d, J =
.3 Hz, 2H); 8.27 (d, J = 8.2 Hz, 2H).
2
2
(90/10)] followed by recrystallisation from hexane/diethylether
yielded the title complex (192 mg, 0.460 mmol, 43% yield) in form
of an orange solid.
1
3
C NMR (C D ): δ = 21.21; 21.26; 67.48; 70.01; 70.73; 71.03;
6
6
[α] = –112 (c = 0.1, CH Cl ).
7
1
1.32; 90.59; 126.29; 126.81; 128.84; 129.58; 138.33; 141.24;
42.14; 143.89.
D 2 2
1H NMR: δ = 2.56 (s, 3H); 3.68 (s, 3H); 4.43 (s, 5H); 4.61–4.67 (m,
2
8
H); 4.82–4.85 (m, 1H); 4.98–5.01 (m, 1H); 7.43–7.48 (m, 2H);
.10–8.14 (m, 2H).
MS (EI, 70 eV): m/z (%) = 493 (M, 100), 428 (91), 91 (42).
~
–1
IR (KBr): n = 1318, 1242, 1151, 1090, 1061, 547 cm .
13C NMR: δ = 21.22; 47.12; 67.89; 70.09; 70.67; 71.37; 88.18;
26.17; 129.00; 141.11; 142.35.
Anal. C H FeNO S (493.42): calcd C, 58.42; H, 4.70; N, 2.84;
24
23
3 2
1
found C, 58.35; H, 4.78; N, 2.55.
+
MS (EI, 70 eV): m/z (%) = 417 (M , 93), 352 (100), 225 (18), 129
(
18), 121 (37), 91 (47), 65 (23), 56 (41).
(
S)- S-t-Butyl-S-ferrocenyl-N-p-tolylsulfonylsulfoximine (8b)
~
–1
Following the general procedure detailed above, (S)-S-t-butyl S-fer-
rocenyl sulfoxide (5b) (234 mg, 0.77 mmol) was reacted with N-(p-
toluenesulfonyl)iminophenyl-λ -iodane (317 mg, 0.85 mmol) in the
presence of copper(I) hexafluorophosphate (68 mg, 0.154 mmol).
Purification by column chromatography [silica gel, CH Cl /acetone
IR (KBr): n = 1314, 1230, 1151, 1091, 1053, 1030, 717, 537 cm .
Anal. C H FeNO S (417.33): calcd C, 51.80; H, 4.59; N, 3.36;
found C, 51.44; H, 4.78; N, 3.18.
3
18 19
3 2
2
2
General Procedure for the Imination of Ferrocenyl Sulfoxides
5
nophenyl-λ -iodane
The ferrocenyl sulfoxide and the copper catalyst were placed in a
dry schlenk flask Ar and were dissolved in freshly distilled MeCN
(95/5)] yielded the title complex (162 mg, 0.35 mmol, 46% yield)
a–e by Means of Hypervalent N-(P-Nitrophenylsulfonyl)imi-
in form of a yellow to orange solid.
3
Suitable crystals of complex 22 for X-ray structure determination
were grown from a solution in CH Cl /hexane at r.t.
2
2
(
10 mL per mmol of substrate). The solution was stirred at r.t. while
[
α] = –189 (c = 0.15, CH Cl ).
D 2 2
3
N-(p-nitrophenylsulfonyl)iminophenyl-λ -iodane (1.4 mmol per 1
mmol of substrate) was added in small portions over a period of 2
h. The mixture was then sealed and stirred at r.t. Conversion was
monitored by tlc and after 48–60 h the mixture was filtered through
a G3 frit followed by standard workup.
1H NMR: δ = 1.25 (s, 9H); 2.40 (s, 3H); 4.42 (s, 5H); 4.49–4.50 (m,
2
7
H); 4.57–4.61 (m, 1H); 4.75–4.80 (m, 1H); 7.26–7.30 (m, 2H);
.95–7.98 (m, 2H).
13C NMR: δ = 21.20; 23.24, 64.84; 69.07; 70.89; 72.55; 85.05;
26.07; 126.13; 128.89; 141.79; 141.83.
1
The crude mixtures were purified as stated below.
MS (EI, 70 eV): m/z (%) = 459 (M, 1), 264 (48), 210 (66), 97 (83),
9
1 (100), 57 (88).
(S)-S-Ferrocenyl-N-p-nitrophenylsulfonyl-S-p-tolylsulfoximine
~
–1
(9a)
IR (KBr): n = 1302, 1233, 1151, 1115, 1090, 545 cm .
Following the general procedure detailed above, 5a (400 mg, 1.24
Anal. C H FeNO S (459.41): calcd C, 54.90; H, 5.48; N, 3.05;
found C, 54.75; H, 5.52; N, 3.05.
3
21
25
3 2
mmol) is reacted with N-(p-nitrophenylsulfonyl)iminophenyl-λ -
iodane (590 mg, 1.49 mmol) in the presence of copper(I) hexafluo-
rophosphate (90.3 mg, 0.248 mmol). Purification by column chro-
matography [silica gel, CH Cl /acetone (95/5)] yielded the title
2
2
Synthesis 1999, No. 7, 1251–1260 ISSN 0039-7881 © Thieme Stuttgart · New York

1
258
C. Bolm et al.
FEATURE ARTICLE
complex (448.3 mg, 0.856 mmol, 69% yield) in form of an orange
solid.
chromatography [silica gel, CH Cl /acetone (95/5)] followed by re-
2
2
crystallization from hexane/Et O yielded the title complex (275.7
2
mg, 0.615 mmol, 68% yield) in form of an orange solid.
[
α] = –85 (c = 0.9, CH Cl ).
D 2 2
1H NMR: δ = 2.39 (s, 3H); 4.29 (s, 5H); 4.41–4.44 (m, 1H); 4.47–
[α] = –90 (c = 0.1, CH Cl ).
D 2 2
1
4
2
.50 (m, 1H); 4.51–4.53 (m, 1H); 4.91–4.93 (m, 1H); 7.26–7.29 (m,
H); 7.73–7.70 (m, 2H); 8.16–8.21 (m, 2H); 8.28–8.33 (m, 2H).
H NMR (CD Cl ): δ = 3.57 (s, 3H); 4.26 (s, 5H); 4.47–4.55 (m,
2 2
2H); 4.62–4.64 (m, 1H); 4.83–4.85 (m, 1H); 8.28 (d, J = 9.0 Hz,
2H); 8.37 (d, J = 9.0 Hz, 2H).
13C NMR: δ = 21.61; 67.80; 70.34; 71.09; 71.62; 72.02; 90.34;
1
3
1
23.92; 126.99; 128.00; 130.05; 137.98; 144.83; 149.50; 149.83.
C NMR (CD Cl ): δ = 47.77; 68.10; 70.34; 71.01; 71.97; 72.06;
2 2
+
87.92; 124.09; 127.95; 149.66; 149.77.
MS (EI, 70 eV): m/z (%) = 524 (M , 1), 346 (1), 340 (9), 308 (4),
2
+
04 (20), 85 (68), 83 (100), 77 (24).
MS (EI, 70 eV): m/z (%) = 448 (M , 100), 383 (56), 121 (13).
~
IR (KBr): n = 1527, 1349, 1331, 1305, 1239, 1174, 1156, 1090,
IR (KBr): n = 1530, 1351, 1325, 1306, 1224, 1170, 1153, 1108,
–
1
–1
1
055, 1030, 1013, 766 cm .
1093, 1069, 1053, 980, 855 cm .
Anal. C H FeN O S (524.39): calcd C, 52.68; H, 3.84; N, 5.34;
HRMS for C H FeN O S : calcd 447.9850; found 447.9851.
23
20
2
5
2
17 16
2
5 2
found C, 52.51; H, 4.09; N, 5.33.
(S)-S-Ferrocenyl-S-(2-methoxynaphthyl)-N-p-nitrophenylsul-
(S)-S-t-Butyl-S-ferrocenyl-N-p-nitrophenylsulfonylsulfoximine
fonylsulfoximine (9e)
(
9b)
Following the general procedure detailed above, 5e (100 mg, 0.26
mmol) was reacted with N-(p-nitrophenylsulfonyl)iminophenyl-λ -
3
Following the general procedure detailed above, 5b (120 mg, 0.41
mmol) was reacted with N-(p-nitrophenylsulfonyl)iminophenyl-λ -
3
iodane (124 mg, 0.31 mmol) the presence of copper(I) hexa-
fluorophosphate (19 mg, 0.051 mmol). Purification by column
chromatography [silica gel, CH Cl /acetone (95/5)] followed by a
iodane (200 mg, 0.492 mmol) in the presence of copper(I) hexa-
fluorophosphate (31 mg, 0.083 mmol). Purification by column
chromatography [silica gel, CH Cl /acetone (95/5)] yielded the title
complex (124.6 mg, 0.25 mmol, 62% yield) in form of an orange
solid.
2
2
second chromatographic purification [silica gel, EtOAc/hexanes
(30/70)] in order to remove some nosyl amide byproduct yielded the
title complex (113.5 mg, 0.192 mmol, 74% yield) in form of an or-
ange solid.
2
2
[
α] = –131 (c = 0.15, CH Cl ).
D 2 2
1
[α] = +69 (c = 0.2, CH Cl ).
D 2 2
H NMR (CD Cl ): δ = 1.22 (s, 9H); 4.49 (s, 5H); 4.54–4.59 (m,
2
2
2
2
H); 4.61–4.63 (m, 1H); 4.78–4.80 (m, 1H); 8.26 (d, J = 9.1 Hz,
H); 8.36 (d, J = 9.1 Hz, 2H).
1H NMR: δ = 3.73 (s, 3H); 4.21–4.40 (m, 1H); 4.44 (s, 5H); 4.45–
4.48 (m, 1H); 4.51–4.55 (m, 1H); 5.12–5.13 (m, 1H); 7.01 (d, J =
9.0 Hz, 1H); 7.42–7.47 (m, 1H); 7.59–7.66 (m, 1H); 7.74–7.76 (m,
1
3
C NMR (CD Cl ): δ = 23.32; 65.47; 69.33; 71.37; 71.42; 71.67;
2
2
1
8
H); 7.91 (d, J = 8.8 Hz, 2H); 7.96 (d, J = 9.1 Hz, 1H); 8.06 (d, J =
.9 Hz, 2H); 9.17 (d, J = 9.1 Hz, 1H).
7
2.97; 84.78; 124.01; 127.74; 149.39; 150.28.
+
MS (EI, 70 eV): m/z (%) = 490 (M , 13), 434 (50), 322 (59), 233
13C NMR: δ = 56.34; 68.30; 70.27; 71.16; 71.36; 72.02; 93.27;
(47), 217 (68), 202 (53), 138 (56), 56 (100).
1
1
12.27; 118.96; 123.32; 123.82; 124.77; 127.94; 128.85; 129.20;
31.58; 137.50; 149.16; 149.28; 157.19.
~
–1
IR (KBr): n = 3103, 1528, 1347, 1329, 1235, 1156, 1098, 658 cm .
Anal. C H FeN O S (490.38): calcd C, 48.99; H, 4.52; N, 5.71;
found C, 48.89; H, 4.55; N, 5.79.
+
20
22
2
5
2
MS (EI, 70 eV): m/z (%) = 590 (M , 100), 525 (7), 233 (11), 115
(10).
~
IR (KBr): n = 3433, 3095, 1527, 1510, 1351, 1328, 1302, 1253,
N-S-ferrocenyl-p-nitrophenylsulfonyl-S-phenylsulfoximine (9c)
Following the general procedure detailed above, 5c (150 mg, 0.48
mmol) was reacted with N-(p-nitrophenylsulfonyl)iminophenyl-λ -
–
1
1
220, 1154, 1106, 1085, 1042, 976, 823, 769, 747, 603 cm .
3
HRMS for C27 : calcd 590.0269; found 590.0268.
H22FeN O S
2 6 2
iodane (234 mg, 0.578 mmol) in the presence of copper(I) hexa-
fluorophosphate (36 mg, 0.096 mmol). Purification by column
chromatography [silica gel, CH Cl /acetone (95/5)] followed by re-
(S)-S-p-Tolyl S-(1’-Tributylstannylferrocenyl) Sulfoxide (11)
A solution of 1,1’-bis(tributylstannyl)ferrocene 10 (1.80 g, 2.44
mmol) in freshly distilled THF (20 mL) under Ar was cooled to
–78°C. At this temperature, BuLi (1.68 mL, 2.69 mmol, 1.6-M so-
lution in hexane) was added dropwise via syringe and the resulting
mixture was stirred for a further 90 min before it was added via can-
nula to a precooled solution of of (–)-menthyl-(S)-(p-tolyl)sulfinate
2
2
crystallization from hexane/Et O yielded the title complex (161.6
2
mg, 0.317 mmol, 66% yield) in form of an orange solid.
1
H NMR (CD Cl ): δ = 4.22 (s, 5H); 4.24–4.39 (m, 1H); 4.44–4.48
2
2
(m, 2H); 4.84–4.85 (m, 1H); 7.38–7.46 (m, 2H); 7.49–7.56 (m, 1H);
7
.75–7.78 (m, 2H); 8.02–8.07 (m, 2H); 8.18–8.23 (m, 2H).
(1.30 g, 4.40 mmol) in THF (40 mL). The mixture was allowed to
1
3
C NMR (CD Cl ): δ = 68.54; 71.08; 71.69; 72.45; 72.90; 124.55;
2
2
reach –30°C within 3 h before it was worked up under standard con-
ditions. The crude product was purified by column chromatography
1
27.49; 128.47; 129.94; 134.18; 141.18; 150.16; 150.30.
+
[silica gel, Et O/hexanes (50/50)] to afford the title compound (1.42
MS (EI, 70 eV): m/z (%) = 510 (M , 100), 445 (38).
2
g, 2.32 mmol, 95% yield) as a deep red oil that was stored under Ar
at –24°C.
~
IR (KBr): n = 1526, 1346, 1326, 1300, 1229, 1162, 1089, 1045,
–1
1
006, 733 cm .
[
α] = +116 (c = 2.0, CH Cl ).
D 2 2
HRMS for C H FeN O S : calcd 510.0007; found 510.0007.
2
2
18
2
5 2
1H NMR: δ = 0.91 (t, J = 7.1 Hz, 9H); 1.03 (t, J = 8.0 Hz, 6H); 1.35
(
dt, J = 7.1, 8.0 Hz, 6H), 1.50–1.61 (m, 6H); 2.36 (s, 3H); 4.17–4.21
(
S)-S-Ferrocenyl-S-methyl-N-p-nitrophenylsulfonylsulfox-
(m, 2H); 4.21–4.24 (m, 1H); 4.26–4.29 (m, 2H); 4.57–4.63 (m, 3H);
imine (9d)
7
.21–7.25 (m, 2H); 7.50–7.54 (m, 2H).
Following the general procedure detailed above, 5d (210 mg, 0.905
mmol) was reacted with N-(p-nitrophenylsulfonyl)iminophenyl-λ -
iodane (439 mg, 1.09 mmol) in the presence of copper(I) hexa-
fluorophosphate (67.4 mg, 0.18 mmol). Purification by column
3
13C NMR: δ = 9.94; 13.42; 21.07; 27.08; 28.86; 64.72; 67.31; 69.64;
69.76; 70.92; 72.21; 75.92; 75.98; 93.88; 124.05; 129.29; 140.64;
142.75.
Synthesis 1999, No. 7, 1251–1260 ISSN 0039-7881 © Thieme Stuttgart · New York

FEATURE ARTICLE
The Search for Benchrotrenes and Ferrocenes Containing a Chiral Sulfoximido Group
1259
+
MS (EI, 70 eV): m/z (%) = 613 (M , 2), 575(100), 541 (13), 434 (7),
8079.
3
14 (8), 211(4).
Bolm, C.; Felder, M. Synlett 1994, 655.
Bolm, C.; Müller, J. Tetrahedron 1994, 50, 4355.
Bolm, C.; Kaufmann, D.; Zehnder, M.; Neuburger, M.
Tetrahedron Lett. 1996, 37, 3985.
~
IR (KBr): n = 2955, 2925, 2870, 2852, 1493, 1463, 1419, 1378,
1
–
1
161, 1084, 1049, 1028, 830, 809, 755 cm .
HRMS for C H FeOSSn: calcd 613.1249; found 613.1258.
2
9
41
Bolm, C.; Müller, J.; Harms, K. Acta Chem. Scand. 1996, 50,
05.
3
(
S)-N-p-Nitrophenylsulfonyl-S-p-tolyl-S-(1’-tributylstannylfer-
Bolm, C.; Bienewald, F.; Harms, K. Synlett 1996, 775.
(3) For applications of sulfoximines in asymmetric stoichiometric
synthesis (reviews and selected recent work), see:
Johnson, C. R. Aldrichim. Acta 1985, 18, 3.
rocenyl)sulfoximine (12)
Following the procedure given above, a reaction of ferrocene 11
(400 mg, 0.65 mmol) with N-(p-nitrophenylsulfonyl)-iminophenyl-
3
λ -iodane (316 mg, 0.78 mmol) in the presence of copper(I)
hexafluorophosphate (49 mg, 0.13 mmol) yielded a crude brown oil
after standard workup. Purification by column chromatography [sil-
ica gel, CH Cl /acetone (90/10)] followed by a second chromato-
Johnson, C. R. Acc. Chem. Res. 1973, 6, 341.
Johnson, C. R. In Comprehensive Organic Chemistry; Barton,
D.; Ollis, W. D. Eds.; Pergamon: Oxford, 1979, Vol. 3, 223.
Pyne, S. G. Sulfur Reports 1992, 12, 57.
2
2
graphy [silica gel, Et O/hexanes (20/80)] afforded the title com-
pound (338 mg, 0.416 mmol, 64% yield) as a deep red oil that was
stored under Ar at –24°C.
Bolm, C.; Müller, J. Chem. Eur. J. 1995, 1, 312.
Gais, H.-J.; Bosshammer, S. Synthesis 1998, 919.
Reggelin, M.; Heinrich, T. Angew. Chem. Int. Ed. 1998, 37,
2
2
883.
[
α] = –49 (c = 0.7, CH Cl ).
D 2 2
(
4) Pérez-Encabo, A.; Perrio, S.; Slawin, A. M. Z.; Thomas, S. E.;
Wierzchleyski, A. T.; Williams, D. J. J. Chem. Soc., Chem.
Commun. 1993, 1059.
1H NMR: δ = 0.91 (t, J = 7.1 Hz, 9H); 1.00 (t, J = 8.0 Hz, 6H); 1.33
dt, J = 7.1, 7.9 Hz, 6H), 1.46–1.58 (m, 6H); 2.39 (s, 3H);); 4.09–
(
4
3
2
.12 (m, 2H); 4.30–4.33 (m, 1H); 4.37–4.40 (m, 1H); 4.44–4.49 (m,
H); 4.86–4.87 (m, 1H); 7.29–7.32 (m, 2H); 7.74 (d, J = 8.6 Hz,
H); 8.19 (d, J = 9.1 Hz, 2H); 8.31 (d, J = 9.1 Hz, 2H).
Pérez-Encabo, A.; Perrio, S.; Slawin, A. M. Z.; Thomas, S. E.;
Wierzchleyski, A. T.; Williams, D. J. J. Chem. Soc. Perkin
Trans I 1994, 629.
13C NMR: δ = 10.22; 13.70; 21.61; 27.30; 29.09; 67.54; 69.98;
7
1
(5) Griffiths, S. L.; Perrio, S.; Thomas, S. E. Tetrahedron:
Asymmetry 1994, 5, 545.
Griffiths, S. L.; Perrio, S.; Thomas, S. E. Tetrahedron:
Asymmetry 1994, 5, 1847.
6) Marcos, C. F.; Perrio, S.; Slawin, A. M. Z.; Thomas, S. E.;
1.63; 72.07; 73.00; 73.96; 77.13; 77.29; 90.06; 123.89; 127.00;
28.05; 130.04; 138.23; 144.74; 149.50; 149.91.
+
MS (EI, 70 eV): m/z (%) = 613 (M , 2), 556 (100), 541 (13), 434 (7),
3
(
14 (8), 91 (8).
Williams, D. J. J. Chem. Soc., Chem. Commun. 1994, 753.
~
IR (KBr): n = 2956, 2926, 1530, 1349, 1332, 1307, 1241, 1180,
1
(7) Takada, H.; Nishibayashi, Y.; Ohe, K.; Uemura, S.; Baird, C.
T.; Sparey, T. J.; Taylor, P. C. J. Org. Chem. 1997, 62, 6512.
Takada, H.; Nishibayashi, Y.; Ohe, K.; Uemura, S.
Phosphorus Sulfur Silicon Relat. Elem. 1997, 120–121, 363.
Takada, H.; Nishibayashi, Y.; Ohe, K.; Uemura, S. Chem.
Commun. 1996, 931.
–
1
158, 1092, 1065, 1051, 730, 657 cm .
HRMS for C H FeN O S Sn (M – C H ): calcd 757.0515; found
7
31
37
2
5
2
4
9
57.0524.
Acknowledgement
(8) Müller, J. F. K.; Vogt, P. Tetrahedron Lett. 1998, 39, 4805.
(
9) Bach, T.; Körber, C. Tetrahedron Lett. 1998, 39, 5015.
We thank J. P. Hildebrand and Dr. O. A. G. Dabard for several fruit-
ful discussions, A. Grenz for a preparative contribution and Dr. H.
Maisch for the measurement of HRMS spectra. We are grateful to
the Fonds der Chemischen Industrie and the Deutsche Forschungs-
gemeinschaft (DFG) within the Collaborative Research Center
(
(
(
10) Davies, S. G.; Loveridge, T.; Clough, J. M. J. Chem. Soc.,
Chem. Commun. 1995, 817.
11) Diter, P.; Samuel, O.; Taudien, S.; Kagan, H. B. Tetrahedron:
Asymmetry 1994, 5, 549.
12) (a) Rebiére, F.; Samuel, O.; Kagan, H. B. Tetrahedron Lett.
(SFB) 380 ‘Asymmetric Synthesis by Chemical and Biological Me-
1
(
990, 31, 3121.
b) Rebiére, F.; Riant, O.; Ricard, L.; Kagan, H. B. Angew.
Chem. Int. Ed. Engl. 1993, 32, 568.
c) Guillaneux, D.; Kagan, H. B. J. Org. Chem. 1995, 60,
502.
thods’ for financial support. N. A. and M. K. thank CIRIT (Genera-
litat de Catalunya) and DFG (Graduiertenkolleg), respectively, for
predoctoral fellowships.
(
2
Supporting information available: A complete reproduction of
the spectral characterization ( H and C NMR) for all new fer-
rocene compounds is available from the authors upon request.
(
(
13) Bolm, C.; Dabard, O. A. G. Synlett 1999, 360.
14) Llera, J. M.; Fernández, I.; Alcudia, F. Tetrahedron Lett.
1
13
1991, 32, 7299.
Fernández, I.; Khiar, N.; Llera, J. M.; Alcudia, F. J. Org.
Chem. 1992, 57, 6789.
15) Pyne, S. G.; Hajipour, A. R.; Prabakaran, K. Tetrahedron Lett.
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(
(
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(
17) Crystallographic data for 8b: C H S O NFe; M : 459.41;
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9
.927(2) Å, α = 69.81(2), β = 76.46(2), γ = 72.48(2) °, V =
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526.7 Å , Z = 1. 3230 independent reflections measured at 225
(
K on a CAD4 Enraf-Nonius diffractometer. MoKα radiation.
The final full-matrix least-squares refinement including 2875
reflections with I > 2σ(I) and 251 variables yields R = 0.052
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Synthesis 1999, No. 7, 1251–1260 ISSN 0039-7881 © Thieme Stuttgart · New York

1
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FEATURE ARTICLE
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−2 28
and R = 0.063 (w = σ ). The absolute configuration of 8b
w
as depicted in Figure 2 was determined by calculation of
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Crystallographic data (excluding structure factors) for the
structure have been deposited at the Cambridge
Crystallographic Data Centre CCDC 118720 Copies of the
data can be obtained free of charge from The Director,
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2
9
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(
(
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Synthesis 1999, No. 7, 1251–1260 ISSN 0039-7881 © Thieme Stuttgart · New York