Combining planar and central chirality in ferrocene thiophosphine- sulfoxides

Article abstract of DOI:10.1016/j.tetasy.2013.04.002

Novel chiral ferrocenylthiophosphine-sulfoxide and phosphine-sulfoxide derivatives possessing planar chirality for the ferrocene moiety and central chirality at the sulfur atom have been synthesized. These ligands can be obtained as pure diastereoisomers

Full text of DOI:10.1016/j.tetasy.2013.04.002

Tetrahedron: Asymmetry 24 (2013) 612–620
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Tetrahedron: Asymmetry
journal homepage: www.elsevier.com/locate/tetasy
Combining planar and central chirality in ferrocene phosphine–sulfoxides
Raluca Malacea a,b, Jean-Claude Daran a,b, Rinaldo Poli a,b,c, Eric Manoury a,b,
⇑
a CNRS, LCC (Laboratoire de Chimie de Coordination), 205 route de Narbonne, BP 44099, F-31077 Toulouse Cedex 4, France
b Université de Toulouse, UPS, INPT, F-31077 Toulouse Cedex 4, France
c Institut Universitaire de France, 103, bd Saint-Michel, 75005 Paris, France
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 25 March 2013
Accepted 12 April 2013
Novel chiral ferrocenylthiophosphine–sulfoxide and phosphine–sulfoxide derivatives possessing planar
chirality for the ferrocene moiety and central chirality at the sulfur atom have been synthesized. These
ligands can be obtained as pure diastereoisomers in both racemic and enantiomerically pure forms. Com-
plete characterization by XRD analysis has allowed the assignment of the absolute configuration in each
case. Preliminary coordination studies of the phosphine–sulfoxide ligands on platinum are also reported.
These show chelating complexation by the phosphorous and sulfur atoms.
Ó 2013 Elsevier Ltd. All rights reserved.
1. Introduction
and enantiomerically pure forms [(RFc)- or (SFc)-configuration],
and reported on their coordination chemistry and applications to
Various chiral bidentate ligands have been developed over the
past few decades, which possess chiral information on the carbon
backbone or on the donor atom. Ligands with various combina-
tions of donor atoms (in particular, P–P, P–N, or N–N ligands) have
been studied extensively and a few P-chirogenic compounds such
as QuinoxP1 or dipamp2 have been shown to be very effective in
a variety of asymmetric catalytic processes. Recently, very efficient
systems for asymmetric catalysis using P–S ligands with various
backbones, have been reported.3,4 Several reports have described
the preparation and coordination chemistry of chiral phosphine
sulfoxide ligands possessing the chirality on the sulfur atom, for
asymmetric catalysis, namely in asymmetric allylic substitutions,
alkene methoxycarbonylations, and ketone hydrogenations.11
Herein we report the synthesis of new
c-ferrocenyl phosphine–
sulfoxide ligands (Fig. 1) and preliminary studies on their coordi-
nation chemistry with platinum.
2. Results and discussion
Starting from the chiral phosphine–thioether ligands already
synthesized in our group, we have developed a new class of
ferrocenyl phosphine–sulfoxide ligand based on the selective
oxidation of the thioether functionality to a sulfoxide. Thus, a ste-
reogenic center on the sulfur atom [(RS) or (SS)] is added to the pla-
nar chirality of ferrocene [(RFc) or (SFc)]. The two diastereoisomers
that can be formed must therefore be subsequently separated.
The first potential issue in the synthetic pathway to the thio-
phosphine–sulfoxides 2 from thiophosphine–thioethers 1 (see
Scheme 1) is the possible over-oxidation to the corresponding sulf-
example
a
-phosphinosulfoxides (PCSO5and PNSO6) or b-phosphi-
nosulfoxides7 (Fig. 1). Riera and Verdaguer8 described ligands with
an extra chiral center in the central carbon atom between the P and
SO and also camphor derivatives combining a stereogenic carbon
backbone with sulfur chirality.9 Kagan’s methodology based on
diastereoselective ortho-lithiation of ferrocenesulfoxide deriva-
tives was used in order to synthesize phosphine–sulfoxide ligands
with additional planar chirality.10 We have recently developed
O
syntheses of new chiral ferrocenyl
c-P,S ligands in both racemic
R
S
PPh2
S
S
H2O2
O
+
Fe
Fe
Fe
PPh2
S
R
PPh2
S
O
S
O
S
R
O
S
O
S
phenol
S
R2
Y
R2
R2
R2
PR1
PHR1
Fe
Fe
2
2
(RS)Fc-2a-c
PR1
(RS)Fc-1a-c
2
PR1
1a
(R=Ph)
2
Y = C, C* or NR
1b (R=Et)
isolated
isolated
1c (R=tBu)
Dia1 + Dia2
2a
Dia2
γ-phosphine sulfoxides
c-Phosphine–sulfoxides.
Dia1
β-phosphine sulfoxides
α-phosphine sulfoxides
91%
2b 93%
2c
41%
44%
Figure 1.
a
-, b-, and
44%
43%
42%
40%
92%
⇑
Corresponding author. Tel.: +33 561333173; fax: +33 561553003.
E-mail address: manoury@lcc-toulouse.fr (E. Manoury).
Scheme 1.
0957-4166/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tetasy.2013.04.002

R. Malacea et al. / Tetrahedron: Asymmetry 24 (2013) 612–620
613
t
ones as well as oxidation of the iron atom to ferrocenium or
conversion of the thiophosphine into a phosphine oxide, as already
observed in the oxidation of related (2-diphenylthiophosphinoferr-
ocenyl)methanol to the corresponding aldehyde.12 Therefore, the
mild method described by Liang Xu13 using an aqueous solution
of H2O2 in the presence of phenol was selected. Under these condi-
tions, the racemic compounds 1a–c (R = Ph, Et, Bu) were trans-
formed into the corresponding thiophosphine–sulfoxides 2a–c
with total conversion and chemoselectivity (no sulfone or other
by-products were observed). For each thioether, two diastereoiso-
mers (each one as a pair of enantiomers) were obtained in a 1:1 ra-
tio. These reactions are rapid (2–3 min) and strongly exothermic.
2a-Dia1 (RFc,SS)/(*)
2a-Dia2 (SFc,SS)/(*)
2b-Dia1 (RFc,RS)/(*)
2c-Dia1 (SFc, RS)/(*)
2c-Dia2 (SFc, SS)/(*)
Figure 2. ORTEP views of 2a-Dia1, 2a-Dia2, 2b-Dia1, 2c-Dia1, and 2c-Dia2 (⁄ the other enantiomer is present in the crystal structure but not represented in the picture) with
the atom labeling scheme. Ellipsoids are drawn at the 50% probability level. H atoms have been omitted for the sake of clarity.

614
R. Malacea et al. / Tetrahedron: Asymmetry 24 (2013) 612–620
For safety reasons, we therefore limited the thioether amount (typ-
ically 250 mg) transformed in each run. Each diastereomer could
be isolated in good yields after separation by column chromatogra-
phy (Scheme 1).
After the diastereomers were separated, the configuration of the
sulfur atom was established by single crystal X-ray diffraction
analysis. The single crystals of 2a-Dia1, 2a-Dia2, 2b-Dia1, 2c-
Dia1, and 2c-Dia2 were obtained by slow diffusion of pentane va-
pors into a dichloromethane solution. These products were ob-
tained from the racemic thiophosphine–thioethers 1a–c (RSFc
)
and crystallize as racemates, except for 2c-Dia2 which afforded a
twin by inversion, therefore also containing both enantiomers
(70:30) in the crystal (see Fig. 2).
To the best of our knowledge, these compounds are the first
structurally characterized ferrocenylthiophosphine–sulfoxides.
Selected geometrical parameters are reported in Table 1. The five
compounds have similar structures with the protecting S(1) endo
with respect to the Cp ring whereas the sulfido S(2) is exo (Table 1).
The distances and angles within the sulfoxide moiety are identical
within experimental error. The two Cp rings are either nearly
eclipsed for 2a-Dia2, 2c-Dia1, and 2c-Dia2B or in between
Figure 3. Molecular fitting of the two molecules 2c-Dia2A and 2c-Dia2B.
eclipsed-staggered for 2a-Dia1, 2b-Dia1, and 2c-Dia2A (s values
in Table 1). In compound 2c-Dia2, there are two molecules within
the asymmetric unit. These molecules have similar configurations
as indicated by the molecular fitting shown in Figure 3. The only
marked difference is the twist angles observed between the two
Cp rings, 12.7(3)° for molecule A and 4.5(3)° for B.
As stated above, no diastereoselectivity was observed under
these oxidation conditions. Other achiral oxidants such as meta-
chloroperbenzoic acid,14 tBuOOH/MoO2(acac)2,15 and chiral ones
such as tBuOOH/diethyltartrate/Ti(OiPr)416 and tBuOOH/diethyltar-
trate/MoO2(acac)2 were then employed. However, all of them gave
lower conversions and no significant improvement in the diastere-
oselectivity relative to Xu’s method. Therefore, our investigations
were continued using the H2O2/phenol system. The next step
S
S
S
PPh2
PPh2
PPh2
H2O2
O
S
R
Fe
Fe
Fe
S
R
S
R
+
OH
phenol
2a-c
(RFc)-1a-c
2a
2b
2c
87% [(RFc, RS)+(RFc, SS)]
87% [(RFc, RS)+(RFc, SS)]
90% [(RFc, RS)+(RFc, SS)]
Scheme 2.
obtained using the compounds in racemic form. Thus, we have ac-
cess to the desired ferrocenylthiothiophosphine-sulfoxides in dia-
stereoisomerically and enantiomerically pure forms.
Since the thioether oxidations were performed on ferrocene
derivatives with the thiophosphine group in order to prevent
was the oxidation of enantiomerically pure thiophosphine–thio-
11a,12
ethers (RFc)-1a-c
which gave the corresponding thiothio-
phosphine-sulfoxides 2a–c as a mixture of two diastereomers in
enantiomerically pure form (Scheme 2). The results obtained
working with enantiomerically pure thioethers are similar to those
Table 1
Selected geometrical parameters for the structures of compounds 2, 3, and 4
2a-Dia1
2a-Dia2
2b-Dia1
2c-Dia1
2c-Dia2A
2c-Dia2B
3a-Dia2a
4ab
Distances (Å)
Fe(1)–Cp(1)
Fe(1)–Cp(2)
C(1)–P(1)
1.6440(11)
1.6582(14)
1.788(2)
1.9611(8)
1.491(3)
1.817(2)
1.499(2)
1.782(3)
1.642(4)
1.654(6)
1.788(8)
1.958(3)
1.502(11)
1.828(8)
1.485(6)
1.787(9)
1.635(1)
1.652(2)
1.802(3)
1.957(1)
1.502(4)
1.825(3)
1.508(2)
1.803(3)
1.640(1)
1.655(1)
1.792(2)
1.9584(8)
1.500(3)
1.811(3)
1.494(2)
1.841(3)
1.642(2)
1.655(2)
1.788(4)
1.958(2)
1.496(5)
1.820(4)
1.495(4)
1.826(5)
1.644(2)
1.659(2)
1.798(4)
1.956(2)
1.495(5)
1.817(4)
1.480(4)
1.840(4)
1.639(1)
1.653(1)
1.816(2)
1.646(2)
1.661(3)
1.796(5)
P(1)–S(1)
C(2)–C(21)
C(21)–S(2)
S(2)–O(2)
1.487(3)
1.823(2)
1.470(2)
1.790(2)
1.481(8)
1.810(5)
1.459(3)
1.782(6)
S(2)–C(22)
Angles (°)
Cp(1)–Fe(1)–Cp(2)
C(2)–C(21)–S(2)
C(21)–S(2)–O(2)
C(21)–S(2)–C(22)
O(2)–S(2)–C(22)
178.53(7)
177.7(2)
111.0(5)
105.5(4)
94.4(4)
177.29(8)
113.1(2)
105.5(1)
97.8(2)
177.42(7)
110.5(2)
105.0(1)
101.0(1)
108.0(1)
178.5(1)
108.1(3)
103.8(2)
100.4(2)
108.0(2)
178.2(1)
107.5(3)
105.8(2)
100.6(2)
108.0(2)
177.90(5)
110.3(1)
105.6(1)
95.65(9)
107.5(1)
176.21(13)
116.2(3)
108.1(2)
97.5(2)
115.90(17)
103.28(13)
100.84(12)
107.50(13)
106.8(4)
106.9(2)
109.1(2)
Distances from plane (Å)
S(1)ꢀ ꢀ ꢀCp(1)
ꢁ0.859(1)
1.500(1)
1.228(2)
ꢁ1.06(2)
1.63(1)
2.49(1)
ꢁ0.921(6)
1.647(5)
1.619(8)
ꢁ1.063(5)
0.457(5)
1.945(5)
ꢁ0.992(8)
1.751(7)
1.654(9)
ꢁ1.154(9)
1.757(7)
1.895(8)
S(2)ꢀ ꢀ ꢀCp(1)
1.619(4)
2.236(4)
0.970(9)
2.186(9)
O(2)ꢀ ꢀ ꢀCp(1)
Twist angle for the Cp rings (°)
12.5(2)
s°
4.0(9)
13.3(2)
1.6(3)
12.7(3)
4.5(3)
4.7(2)
14.5(3)
a
3a Dia2: (SFc,SS)/(RFc,RS)-3a.
4a: (RFc,RS)/(SFc,SS)-4a.
b

R. Malacea et al. / Tetrahedron: Asymmetry 24 (2013) 612–620
615
R
R
(SFc, RS)/(RFc, SS)-3a (93%)
(SFc, SS)/(RFc, RS)-3a (85%)
(SFc, SS)/(RFc, RS)-3b (66%)
(SFc, RS)/(RFc,SS)-3b (65%)
(SFc, RS)/(RFc, SS)-3c (76%)
(SFc, SS)/(RFc, RS)-3c (86%)
S
S
P(NMe2)3
toluenere flux
O
O
Fe
PPh2
Fe
PPh2
S
3 h
2a-c (Dia 1 or Dia 2)
3
Scheme 3.
phosphorus oxidation, the next step was a phosphorus deprotec-
tion in order to liberate the free phosphine group and generate
ferrocenyl phosphine–sulfoxides that could be used as chiral
bidentate P–S ligands. This reaction was carried out using
tris(dimethylamino)phosphine in refluxing toluene for 3 h
(Scheme 3).11a A longer reaction time caused partial deoxygenation
of the sulfoxide group. Since the phosphine–sulfoxide compounds
3a–c were air sensitive, their purification was accomplished by col-
umn chromatography under argon with yields of isolated products
ranging from 65% to 93%. Single crystals of (SFc,SS)-/(RFc,RS)-3a were
obtained by slow diffusion of pentane vapors into a dichlorometh-
ane solution; the XRD structure is shown in Figure 4. The confor-
mation of this unprotected ligand did not show any significant
differences relative to the protected one (SFc,SS)-/(RFc,RS)-3a
(Table 1).
Figure 5. ORTEP view of platinum complex (RFc,RS)-4a with the atom labeling
scheme. The other enantiomer (not shown) is also present in the crystal. Ellipsoids
are drawn at the 50% probability level. H atoms have been omitted for the sake of
0
clarity. Selected bond lengths (AÅ): Pt–P: 2.2350(12); Pt–S: 2.2291(12); Pt–Cl1(trans
S): 2.2973(12); Pt–Cl2(trans P): 2.3312(13); S–O: 1.459.
(d1 = 0.72 ppm, JP–Pt = 3338 Hz and d2 = 0.47 ppm, JP–Pt = 3444 Hz)
in a 1:1 ratio. The 1JPtP value is characteristic of square planar com-
plexes with cis chlorine atoms.18 Crystals of one complex were ob-
tained by diffusion of pentane into a dichloromethane solution, and
thus the coordination mode of the sulfoxide group as
determined from the XRD structure (see Fig. 5).
j
2-PS was
The Pt atom is surrounded by the S2, P1, Cl1 and Cl2 donor
atoms in a square planar coordination geometry. It deviates from
the least squares plane defined by these four atoms by only
ꢁ0.0181(7) Å. The C1, C2, C21, S2, Pt1, and P1 metallacycle display
a boat conformation as indicated by the puckering parameters
u
= 302.6(3)° and h = 87.9(3).19 The S2 and O2 atoms are endo with
respect to the Cp1 ring by ꢁ0.970(9) and ꢁ2.186(9) Å, respectively.
The coordination has induced a slight twist of the two Cp rings
(s = 14.5(4)°) when compared to the uncoordinated ligand which
was roughly eclipsed with a twist angle of 4.7(2)°.
The crystallized compound corresponds to the racemic diaste-
reomer with the (RFc,RS)/(SFc,SS)-configuration. Given the similarity
of the NMR signals, we attribute structure 4a0 to the second com-
pound with the (SFc,RS)/(RFc,SS)-configuration (Scheme 4).
Figure 4. ORTEP view of the phosphine sulfoxide 3a-Dia2 (SFc,SS) with the atom
labeling scheme. Ellipsoids are drawn at the 50% probability level. H atoms have
been omitted for the sake of clarity.
The presence of two complexes in a 1:1 ratio in the product sug-
gests that the two diastereomeric ferrocenyl phosphine–sulfoxide
ligands do not have significantly different reactivities with the
platinum precursor. This might be surprising given that in the case
of the corresponding ferrocenyl phosphine thioethers, we observed
a total discrimination between the two electron pairs for coordina-
tion with platinum, palladium,20 or iridium.21 Our attempts to ob-
tain complex 4a via oxidation of the sulfur atom in the
Since the P, SO ligands could adopt different coordination modes
(j j j
2-PS, 2-PO, or 1-P),17 we carried out preliminary coordination
chemistry investigations with platinum, by reacting the phos-
phine–sulfoxide ligand 3a (as the racemic diastereoisomeric mix-
ture, Dia1/Dia2 = 1/1) with the platinum precursor PtCl2(CH3CN)2.
The 31P{1H} NMR analysis of the final mixture shows the presence
of two signals corresponding to two similar platinum complexes
O
S
Cl
Pt
Ph2
P
Ph
Cl
O
S
Cl
+ PtCl2(CH3CN)2
Ph
Pt
Fe
Ph
S
P
PPh2
Fe
Fe
toluene
Ph2
reflux 3h
Cl
O
4a
4a'
(SFc, RS)/(RFc, SS)
3a
(Dia 1 + Dia 2)
(RFc, RS)/(SFc, SS)
Scheme 4.

616
R. Malacea et al. / Tetrahedron: Asymmetry 24 (2013) 612–620
coordination sphere of the corresponding phosphine–thioether
platinum precursor (Ph2P–Fc–CH2SPh)PtCl2 were unsuccessful
(conditions: mCPBA, THF, reflux, 20 h). The oxidation reaction did
not occur and the starting material was recovered quantitatively.
JCP = 9 Hz, subst Cp); 74.6 (d, JCP = 12 Hz, subst Cp); 71.6 (s, Cp);
70.4 (d, JCP = 10 Hz, subst Cp); 58.0 (s, CH2Cp). 31P{1H} NMR (d,
202.5 MHz, CDCl3): 43.5. Elemental analysis: C29H25FePS2O; %C
(calcd 64.44, found 62.84), %H (calcd 4.63, found 5.03).
20
(RFc,RS)/(SFc,SS)-2a: 1H NMR (d, 500 MHz, CDCl3): 7.89 (2H, m,
Ph); 7.87 (2H, m, Ph); 7.6–7.40 (11H, m, Ph); 5.34 (1H, d(AB),
JHH = 13 Hz, CH2Cp); 4.85 (1H, m, subst Cp); 4.49 (1H, m, subst
Cp); 4.30 (5H, s, Cp); 3.87 (1H, m, subst Cp); 3.61 (1H, d(AB),
JHH = 13 Hz, CH2Cp). 13C{1H} NMR (d, 125.8 MHz, CDCl3): 134.9 (d,
JCP = 87 Hz, quat PPh2); 133.2 (d, JCP = 87 Hz, quat PPh2); 132.7 (d,
JCP = 11 Hz, PPh2); 132.4 (d, JCP = 11 Hz, PPh2); 132.1 (d, JCP = 3 Hz,
PPh2); 132.0 (d, JCP = 3 Hz, PPh2); 130.9 (s, SPh); 129.5 (s, SPh);
129.4 (s, quatSPh); 128.8 (d, JCP = 13 Hz, PPh2); 128.6 (d,
JCP = 13 Hz, PPh2); 123.9 (s, SPh); 83.0 (d, JCP = 12 Hz, quat Cp);
76.2 (d, JCP = 9 Hz, subst Cp); 75.8 (d, JCP = 12 Hz, subst Cp); 74.8
(d, JCP = 95 Hz, quat Cp); 71.4 (s, Cp); 71.1 (d, JCP = 10 Hz, subst
Cp); 61.1 (s, CH2Cp). 31P{1H} NMR (d, 202.5 MHz, CDCl3): 43.9. Ele-
mental analysis: C29H25FePS2O; %C (calcd 64.44, found 64.12), %H
(calcd 4.63, found 4.32).
3. Conclusion
In conclusion, we have described the synthesis of new ferroce-
nyl derivatives thiophosphine–sulfoxides 2a–c and phosphine–
sulfoxides 3a–c with aromatic or aliphatic substituents on the
sulfur atom. These ligands possess planar chirality for the ferro-
cene moiety and a stereogenic center at the sulfur atom and could
be obtained as pure diastereoisomers in both racemic and enanti-
omerically pure forms. Most of these compounds were fully char-
acterized by XRD analysis allowing the assignment of the
absolute configuration for each stereoisomer. Preliminary coordi-
nation studies of these ligands were carried out with platinum,
demonstrating bidentate
j
2-PS complexation in this case. The
enantiomerically pure ligands are currently being tested in various
catalytic asymmetric reactions in our laboratories and our results
will be presented in due course.
4.3. 2-Thiodiphenylphosphino-(ethyl-sulfoxymethyl)-ferrocene
2b
4. Experimental
4.1. General
Following the same procedure described above for the synthesis
of 2a, the reaction was realized starting from 250 mg (0.52 mmol)
of racemic thioether (R/S)Fc-1b, 500 mg of phenol and 0.10 ml of an
aqueous solution of H2O2 (30%). Compound 2b was recovered as an
orange solid (yield: 241 mg, 93%). The two diastereomers were
separated by chromatography on silica using a mixture of ether
and dichloromethane (1/1) as eluent to give 114 mg of 2b-Dia1,
(RFc,RS)/(SFc,SS)-2b (yield: 44%) and 109 mg of 2b-Dia2, (RFc,SS)/
(SFc,RS)-2b (yield: 42%). MS (DCI, NH3): m/z = 493 (M+1, 45%);
510 (M+NH4, 100%).
All reactions were carried out under argon using standard
Schlenk line techniques. Solvents were carefully dried by conven-
tional methods and distilled under argon before use. The NMR
spectra were recorded on a Bruker DRX-500 Avance instrument
with degassed solvents. Elemental analyses were recorded on Per-
kin Elmer 2400 II. The mass spectra were recorded on a Nermag R-
10-10H spectrometer.
(RFc,RS)/(SFc,SS)-2b: 1H NMR (d, 500 MHz, CDCl3): 7.85–7.81 (2H,
m, PPh2); 7.66–7.47 (6H, m, PPh2); 7.43 (2H, br s, PPh2); 4.90 (1H, s,
subst Cp); 4.47 (1H, s, subst Cp); 4.36 (5H, s, Cp); 4.45–4.28 (2H, m,
CH2Cp); 3.87 (1H, s, subst Cp); 2.35 (2H, br s, CH2CH3); 1.1 (3H, br s,
CH2CH3). 13C{1H} NMR (d, 125.8 MHz, CDCl3): 133.9 (d, JCP = 87 Hz,
quat PPh2); 132.1 (d, JCP = 86 Hz, quat PPh2); 132.0 (d, JCP = 11
Hz, PPh2); 131.9 (s, PPh2); 131.8 (br s, PPh2); 128.7 (d, JCP = 12 Hz,
PPh2); 128.5 (d, JCP = 12 Hz, PPh2); 82.0 (d, JCP = 12 Hz, quat Cp);
74.8 (s, subst Cp); 74.7 (d, JCP = 12 Hz, subst Cp); 74.0 (d,
JCP = 96 Hz, quat Cp); 71.3 (s, Cp); 70.8 (d, JCP = 10 Hz, subst Cp);
50.6 (s, CH2Cp); 44.7 (s, CH2CH3); 7.6 (s, CH2CH3). 31P{1H} NMR
(d, 202.5 MHz, CDCl3): 41.06. Elemental analysis: C25H25FePS2O;
%C (calcd 60.98, found 61.08), %H (calcd 5.08, found 5.17).
(RFc,SS)/(SFc,RS)-2b: 1H NMR (d, 500 MHz, CDCl3): 7.83–7.79 (2H,
m,PPh2); 7.59–7.48 (6H, m, PPh2); 7.41 (2H, br s, PPh2); 5.26 (1H,
d(AB),JHH = 13 Hz, CH2Cp); 4.81 (1H, s, subst Cp); 4.47 (1H, s, subst
Cp); 4.32 (5H, s, Cp); 3.82 (1H, s, subst Cp); 3.53 (1H, d(AB),
JHH = 13 Hz, CH2Cp); 2.65 (2H, q, JHH = 7 Hz, CH2CH3); 1.5 (3H, br
s, CH2CH3). 13C{1H} NMR (d, 125.8 MHz, CDCl3): 134.1 (d,
JCP = 88 Hz, quat PPh2); 132.3 (d, JCP = 88 Hz, quat PPh2); 132.0 (d,
JCP = 11 Hz, PPh2); 131.9 (br s, PPh2); 128.6 (d, JCP = 12 Hz, PPh2);
128.5 (d, JCP = 13 Hz, PPh2); 82.5 (d, JCP = 10 Hz, quat Cp); 75.8 (d,
JCP = 9 Hz, subst Cp); 75.5 (d, JCP = 12 Hz, subst Cp); 73.1 (d,
JCP = 95 Hz,quat Cp); 71.2 (s, Cp); 71.1 (s, subst Cp); 53.4 (s, CH2Cp);
46.7 (s, CH2CH3); 7.1 (s, CH2CH3). 31P{1H} NMR (d, 202.5 MHz,
CDCl3):41.6. Elemental analysis: C25H25FePS2O; %C (calcd 60.98,
found 60.98), %H (calcd 5.08, found 4.83).
4.2. 2-Thiodiphenylphosphino-(phenyl-sulfoxymethyl)ferro-
cene 2a
In
a Schlenk tube under argon were introduced 240 mg
(0.45 mmol) of racemic thioether (R/SFc)-1a and 500 mg
(5.4 mmol) of phenol. The mixture was heated to 35 °C, then
0.1 ml of an aqueous solution of H2O2 (30%) was slowly added to
the reaction medium. The reaction was highly exothermic and
within minutes the solution turned black. After 5 min, 10 ml of
ethyl acetate, then 10 ml of a saturated solution of Na2SO3, and fi-
nally 20 ml of an aqueous solution of NaOH (10%) were added. The
phases were separated and the aqueous phase was extracted with
three portions (10 ml) of ethyl acetate. The combined organic lay-
ers were washed with water, dried over MgSO4 and then the sol-
vent was removed by evaporation under reduced pressure.
Compound 2a was recovered as an orange solid (yield: 226 mg,
92%). The two diastereomers were separated by chromatography
on silica using a mixture of ether and dichloromethane (1/1) as elu-
ent to give 100 mg of 2a-Dia1, (RFc,SS)/(SFc,RS)-2a (yield: 41%) and
108 mg of 2a-Dia2, (RFc,RS)/(SFc,SS)-2a (yield: 44%). MS (DCI,
NH3): m/z = 541 (M+1, 20%); 558(M+NH4, 100%).
(RFc,SS)/(SFc,RS)-2a: 1H NMR (d, 500 MHz, CDCl3): 7.86 (2H, m,
Ph); 7.65–7.40 (13H, m, Ph); 4.48 (1H, br s, subst Cp); 4.44 (5H,
s, Cp); 4.35 (1H, br s, subst Cp); 4.32 (1H, d(AB), JHH = 13 Hz,
CH2Cp); 4.30 (1H, d(AB), JHH = 13 Hz, CH2Cp); 3.87 (1H, br s, subst
Cp).13C{1H} NMR (d, 125.8 MHz, CDCl3):144.5 (s, quatSPh); 134.8
(d, JCP = 87 Hz, quat PPh2); 133.1 (d, JCP = 86 Hz, quat PPh2); 132.5
(d, JCP = 11 Hz, PPh2); 132.3 (d, JCP = 11 Hz, PPh2); 131.96 (s,
PPh2); 131.9 (s, PPh2); 131.3 (s, SPh); 129.4 (s, SPh); 128.9 (d,
JCP = 13 Hz, PPh2); 128.6 (d, JCP = 13 Hz, PPh2); 124.8 (s, SPh); 83.1
(d, JCP = 12 Hz, quat Cp); 75.8 (d, JCP = 95 Hz, quat Cp); 75.4 (d,
4.4. 2-Thiodiphenylphosphino-(tert-butyl-sulfoxymethyl)-
ferrocene 2c
Following the same procedure described above for the synthesis
of 2a, the reaction was carried out starting from 250 mg

R. Malacea et al. / Tetrahedron: Asymmetry 24 (2013) 612–620
617
(0.496 mmol) of racemic thioether (R/S)Fc-1c, 500 mg of phenol,
and 0.10 ml of an aqueous solution of H2O2 (30%). Compound 2c
was recovered as an orange solid (yield: 237 mg, 92%). The two dia-
stereomers were separated by chromatography on silica using a
mixture of ether and acetone (5%) as eluent to give 111 mg of
2c-Dia1, (RFc,SS)/(SFc,RS)-2c (yield: 43%) and 103 mg of 2c-Dia2,
(RFc,RS)/(SFc,SS)-2c (yield: 40%). MS (DCI, NH3): m/z = 521 (M+1,
100%); 538 (M+NH4, 80%).
4.8. (RFc,SS)/(SFc,RS)-2-Diphenylphosphino-(phenyl-sulfoxymeth-
yl)-ferrocene 3a-Dia1
In
a Schlenk tube under argon were introduced 81 mg
(0.15 mmol) of racemic sulfoxide (RFc,SS)/(SFc,RS)-2a-Dia1 in 5 ml
of toluene and 0.2 ml (0.18 g, 1.1 mmol) of tris(dimethyl-
amino)phosphine. After refluxing for 3 h, the solvent was removed
by evaporation and the crude reaction mixture was purified by col-
umn chromatography on silica using degassed ether as eluent. The
sulfoxide phosphine (RFc,SS)/(SFc,RS)-3a-Dia1 was obtained as an
orange liquid (yield: 71 mg, 93%). 1H NMR (d, 500 MHz, CDCl3):
7.64–7.49 (4H, m, Ph); 7.49–7.32 (6H, m, Ph); 7.32–7.12 (5H, m,
Ph); 4.43 (1H, dd(ABX), JHH = 13 Hz, JHP = 2 Hz, CH2Cp); 4.42 (1H,
br s, subst Cp); 4.22 (1H, t, JHH = 2 Hz, subst Cp); 4.01 (5H, s, Cp);
3.90 (1H, br s, subst Cp); 3.74 (1H, d(AB), JHH = 13 Hz, CH2Cp).
31P{1H} NMR (d, 202.5 MHz, CDCl3): ꢁ22.5.
(RFc,SS)/(SFc,RS)-2c: 1H NMR (d 500 MHz, CDCl3): 7.8 (2H, m,
PPh2); 7.58–7.47 (6H, m, PPh2); 7.40 (2H, m, PPh2); 5.07 (1H, br
s, subst Cp); 4.47 (1H, br s, CH2Cp); 4.41(5H, s, Cp); 4.41 (1H, s,
subst Cp); 3.78 (1H, s, subst Cp); 3.05 (1H, d(AB), JHH = 14 Hz,
CH2Cp); 1.32 (9H, s, C(CH3)3). 13C{1H} NMR (d,125.8 MHz, CDCl3):
134.6 (d, JCP = 87 Hz, quat PPh2); 132.4 (d, JCP = 86 Hz, quat PPh2);
131.9 (d, JCP = 11 Hz, PPh2); 131.7 (d, JCP = 11 Hz, PPh2); 131.6 (d,
JCP = 3 Hz, PPh2); 131.5 (d, JCP = 3 Hz, PPh2); 128.6 (d, JCP = 13 Hz,
PPh2); 128.2 (d, JCP = 13 Hz, PPh2); 85.2 (d, JCP = 12 Hz, quat Cp);
74.9 (d, JCP = 96 Hz, quat Cp); 73.8 (d, JCP = 12 Hz, subst Cp); 73.6
(d, JCP = 19 Hz, subst Cp); 71.1 (s, Cp); 70.0 (d, JCP = 9 Hz, subst
Cp); 54.2 (br s, C(CH3)3); 44.9 (s, CH2Cp); 23.1 (s, C(CH3)3).
31P{1H} NMR (d,202.5 MHz, CDCl3): 41.8. Elemental analysis:
4.9. (RFc,RS)/(SFc,SS)-2-Diphenylphosphino-(phenyl-sulfoxymeth-
yl)-ferrocene 3a-Dia2
Following the same procedure described above for the desulfur-
ization of (RFc,SS)/(SFc,RS)-2a-Dia1, the reaction was realized from
92 mg (0.17 mmol) of racemic sulfoxide (RFc,RS)/(SFc,SS)-2a-Dia2
and 0.2 ml (0.18 g, 1.1 mmol) of tris(dimethylamino)phosphine.
The crude reaction mixture was purified by column chromatogra-
phy on silica using degassed ether as eluent. The sulfoxide phos-
phine product (RFc,RS)/(SFc,SS)-3a-Dia2 was obtained as an orange
solid (yield: 73 mg, 85%). 1H NMR (d,500 MHz, CDCl3): 7.65–7.5
(3H, m, Ph); 7.5–7.35 (6H, m, Ph); 7.35–7.2 (6H, m, Ph); 4.77 (1H,
d, JHH = 1 Hz, subst Cp); 4.43 (1H, t, JHH = 3 Hz, subst Cp); 4.17
(1H, dd(ABX), JHH = 13 Hz, JHP = 3 Hz, CH2Cp); 3.99 (5H, s, Cp);
3.85 (1H, t, JHH = 1 Hz, subst Cp); 3.77 (1H, d(AB), JHH = 13 Hz,
CH2Cp). 31P{1H} NMR (d, 202.5 MHz, CDCl3): ꢁ20.9.
C
27H29FePS2O; %C (calcd 62.31, found 62.16), %H (calcd 5.58, found
5.54).
(RFc,RS)/(SFc,SS)-2c: 1H NMR (d,500 MHz, CDCl3): 7.83 (1H, dd,
JHH = 2 Hz, JHP = 14 Hz, C6H5); 7.82 (1H, dd, JHH = 2 Hz,
m
JHP = 15 Hz, m C6H5); 7.66 (1H, dd, JHH = 2 Hz, JHP = 15 Hz, m
C6H5); 7.65 (1H, dd, JHH = 2 Hz, JHP = 15 Hz, m C6H5); 7.58–7.53
(1H, m, p C6H5); 7.52–7.45 (3H, m, p+2o C6H5); 7.42–7.37 (2H, m,
2o C6H5); 5.09 (1H, d(AB). JHH = 13 Hz, CH2Cp); 4.89 (1H, m, subst
Cp); 4.43 (1H, m, subst Cp); 4.37 (5H, s, Cp); 3.75 (1H, m, subst
Cp); 3.28 (1H, d(AB), JHH = 13 Hz, CH2Cp); 1.04 (9H, s,C(CH3)3).
13C{1H} NMR (d,125.8 MHz, CDCl3):134.02 (d, JCP = 87 Hz, quat
PPh2); 132.87 (d, JCP = 82 Hz, quat PPh2); 132.53 (d, JCP = 10 Hz, m
PPh2); 131.97 (d, JCP = 10 Hz, m PPh2); 131.50 (d, JCP = 3 Hz, pPPh2);
131.45 (d, JCP = 3 Hz, p PPh2); 128.23 (d, JCP = 4 Hz, o PPh2); 128.13
(d. JCP = 4 Hz, o PPh2); 83.50 (d, JCP = 12 Hz, quat Cp); 75.20 (d,
JCP = 9 Hz, subst Cp); 75.07 (d, JCP = 13 Hz, subst Cp); 74.47 (d,
JCP = 95 Hz, quat Cp); 71.04 (s, Cp); 70.41 (d, JCP = 10 Hz, subst
Cp); 53.23 (s, C(CH3)3); 47.84 (s, CH2Cp); 22.75 (s, C(CH3)3).
31P{1H} NMR (d, 202.5 MHz, CDCl3): 41.4. Elemental analysis:
C27H27FePS2O; %C (calcd 62.31, found 59.81), %H (calcd 5.58, found
5.58).
4.10. (RFc,RS)/(SFc,SS)-2-Diphenylphosphino-(ethylsulfoxymeth-
yl)ferrocene 3b-Dia1
In
a Schlenk tube under argon were introduced 77 mg
(0.157 mmol) of the racemic sulfoxide (RFc,RS)/(SFc,SS)-2b-Dia1 in
5 ml of toluene and 0.2 ml (0.18 g, 1.1 mmol) of tris(dimethyl-
amino)phosphine. After reflux for 2 h, the solvent was evaporated
under reduced pressure and the crude reaction product was puri-
fied by column chromatography on silica using degassed ether/
dichloromethane mixture (1/0–1/1) as eluent. The sulfoxide-phos-
phine product (RFc,RS)/(SFc,SS)-3b-Dia1 was obtained as an orange
solid (yield: 48 mg, 66%).1H NMR (d, 500 MHz, CDCl3): 7.62–7.50
(3H, m, Ph); 7.44–7.35 (2H, m, Ph); 7.28–7.08 (5H, m, Ph); 4.62
(1H, q, JHH = 1 Hz, subst Cp); 4.39 (1H, t, JHH = 3 Hz, subst Cp);
4.15 (1H, dd(ABX), JHH = 14 Hz, JHP = 2 Hz, CH2Cp); 4.03 (5H, s,
Cp); 3.93 (1H, d, JHH = 1 Hz subst Cp); 3.76 (1H, d(AB), JHH = 14 Hz,
CH2Cp); 2.37 (1H, dq, JHH = 7.7 Hz, JHP = 2.7 Hz, CH2CH3); 1.12 (1H,
t, JHH = 7.7 Hz, CH2CH3). 31P{1H} NMR (d, 202.5 MHz, CDCl3): ꢁ22.5,
MS (DCI, NH3): m/z = 461(M+1, 100%).
4.5. Synthesis of enantiomerically pure (RFc)-2-thiodiphenyl
phosphino-(phenylsulfoxymethyl)ferrocene (RFc)-2a
The reaction was carried out using enantiomerically pure (RFc)-
1a following the same procedure described above for the synthesis
of racemic 2a. Dia1, (RFc,SS)-2a: ½a D21
¼ ꢁ100:2 (c 0.49, CHCl3);
ꢂ
Dia2, (RFc,RS)-2a: ½a D21
¼ þ14:2 (c 0.49, CHCl3).
ꢂ
4.6. (RFc)-2-Thiodiphenylphosphino-(ethylsulfoxymethyl)ferro-
cene (RFc)-2b
The reaction was carried out using enantiomerically pure (RFc)-
1b following the same procedure described above for the synthesis
4.11. (RFc,SS)/(SFc,RS)-2-Diphenylphosphino-(ethylsulfoxymeth-
yl)ferrocene 3b-Dia2
of racemic 2b. Dia1, (RFc,RS)-2b: ½a D21
¼ ꢁ110:2 (c 0.5, CHCl3); Dia2,
ꢂ
(RFc,SS)-2b: ½a D21
ꢂ
¼ þ32:1 (c 0.505, CHCl3).
Following the same procedure described above for the desulfur-
ization of (RFc,RS)/(SFc,SS)-2b-Dia1, the reaction was realized from
55 mg (0.112 mmol) of racemic sulfoxide (RFc,SS)/(SFc,RS)-2b-Dia2
and 0.2 ml (0.18 g, 1.1 mmol) of tris(dimethylamino)phosphine.
The crude reaction product was purified by column chromatogra-
phy on silica using a degassed ether/methanol mixture (1/0–95/
5) as the eluent. The sulfoxide phosphine product (RFc,SS)/(SFc,RS)-
3b-Dia2 was obtained as an orange solid (yield: 33 mg, 65%). 1H
NMR (d, 500 MHz, CDCl3): 7.62–7.48 (3H, m, Ph); 7.43–7.35 (3H,
4.7. (RFc)-2-Thiodiphenylphosphino-(tert-butylsulfoxymethyl)
ferrocene (RFc)-2c
The reaction was carried out using enantiomerically pure (RFc)-
1c following the same procedure described above for the synthesis
of racemic 2c. Dia1, (RFc,SS)-2c: ½a D21
¼ ꢁ152:2 (c 0.5, CHCl3); Dia2,
ꢂ
(RFc,RS)-2c: ½a D21
¼ þ5:0 (c 0.515, CHCl3).
ꢂ

618
R. Malacea et al. / Tetrahedron: Asymmetry 24 (2013) 612–620
Table 2
Crystal data and structure refinement parameters
Identification code
2a-Dia1
29H25FeOPS2
540.43
180(2)
0.71073
Monoclinic
Cc
14.5928(10)
18.4079(11)
9.4244(6)
90.0
2a-Dia2
2b-Dia1
Empirical formula
Formula weight
Temperature (K)
Wavelength (Å)
Crystal system
Space group
a (Å)
C
C29H25FeOPS2
540.43
180(2)
0.71073
Monoclinic
P21/a
12.812(2)
9.4172(16)
21.896(4)
90.0
C25H25FeOPS2
492.39
180(2)
0.71073
Orthorhombic
Pcab
8.1197(6)
16.9489(11)
33.823(2)
90.0
b (Å)
c (Å)
a
(°)
b (°)
93.858(5)
90.0
2525.9(3)
4
1.421
0.847
104.832(16)
90.0
2553.8(8)
4
1.322
0.754
90.0
90.0
4654.7(5)
8
1.405
0.911
2048
0.52 ꢃ 0.39 ꢃ 0.12
3.32–26.37
33297
c
(°)
Volume (Å3)
Z
Density (calcd) (Mg/m3)
Absorption coefficient (mmꢁ1
F(000)
)
1120
1056
Crystal size (mm3)
Theta range (°)
Reflections collected
0.45 ꢃ 0.42 ꢃ 0.2
3.56–27.81
9974
0.16 ꢃ 0.10 ꢃ 0.05
2.71–26.03
18130
Independent reflections [R(int)]
Completeness (%)
4487 (0.0242)
99.7
5055 (0.1527)
99.7
4751 (0.0634)
99.8
Absorption correction
Max., min. transmission
Refinement method
Multiscan
0.8415 and 0.6881
F2
Multi-scan
1.0500 and 0.8078
F2
Multi-scan
0.8230 and 0.6750
F2
Data/restraints/parameters
4487/2/308
1.055
5055/0/307
0.892
4751/0/272
1.081
Goodness-of-fit on F2
Final R indices [I >2sigma(I)]
R indices (all data)
0.0278, 0.0642
0.0305, 0.0656
0.019(14)
0.326 and ꢁ0.219
0.0662, 0.1564
0.1713, 0.2309
0.0514, 0.1035
0.0704, 0.1118
Absolute structure parameter
Largest diff. peak and hole (e Åꢁ3
)
0.711 and ꢁ0.865
0.417 and ꢁ0.367
Empirical formula
Formula weight
Temperature (K)
Wavelength (Å)
Crystal system
Space group
a (Å)
C27H29FeOPS2
520.44
180(2)
0.71073
Monoclinic
Cc
11.8130(12)
14.8503(12)
13.9653(16)
90.0
91.394(13)
90.0
2449.2(4)
4
1.411
C27H29FeOPS2
520.44
180(2)
0.71073
Monoclinic
P21
14.7673(14)
10.1912(7)
17.0533(18)
90.0
98.030(12)
90.0
2541.3(4)
4
1.360
C29H25FeOPS
508.37
180(2)
0.70930
Triclinic
P-1
7.8035(8)
9.3075(9)
17.5040(15)
79.331(7)
87.727(7)
77.299(8)
1218.8(2)
2
1.385
0.790
528
0.35 ꢃ 0.32 ꢃ 0.2
3.47–28.22
10784
b (Å)
c (Å)
a
(°)
b (°)
c
(°)
Volume (Å3)
Z
Density (calcd) (Mg/m3)
Absorption coefficient (mmꢁ1
F(000)
)
0.870
1088
0.76 ꢃ 0.22 ꢃ 0.2
2.62–26.04
11892
0.838
1088
0.56 ꢃ 0.52 ꢃ 0.02
2.33–26.08
21668
Crystal size (mm3)
Theta range (°)
Reflections collected
Independent reflections [R(int)]
Completeness (%)
4769 (0.0442)
98.8
9539 (0.0730)
97.7
6009 (0.0237)
99.1
Absorption correction
Max., min. transmission
Refinement method
Multi-scan
0.943 and 0.610
F2
Multi-scan
0.8058 and 0.7391
F2
Multi-scan
0.7521 and 0.6862
F2
Data/restraints/parameters
4769/2/292
1.025
9539/1/584
0.843
6009/0/298
0.991
Goodness-of-fit on F2
Final R indices [I>2sigma(I)]
R indices (all data)
0.0302, 0.0778
0.0314, 0.0785
ꢁ0.004(11)
0.318 and ꢁ0.384
0.0379, 0.0611
0.0716, 0.0685
0.284(14)
0.328 and ꢁ0.425
0.0389, 0.1012
0.0507, 0.1067
Absolute structure parameter
Largest diff. peak and hole (e Åꢁ3
)
1.418 and ꢁ0.385
Identification code
Empirical formula
Formula weight
Temperature (K)
Wavelength (Å)
Crystal system
Space group
a (Å)
4a
C
29H25Cl2FeOPPt S
774.36
180(2)
0.71073
Monoclinic
P21/n
18.6057(14)
7.5780(7)
19.3027(14)
90.0
b (Å)
c (Å)
a
(°)
(continued on next page)

R. Malacea et al. / Tetrahedron: Asymmetry 24 (2013) 612–620
619
Table 2 (continued)
b (°)
107.659(8)
90.0
2593.3(4)
4
1.983
6.319
1504
0.18 ꢃ 0.08 ꢃ 0.08
2.21–26.06
24800
c
(°)
Volume (Å3)
Z
Density (calcd) (Mg/m3)
Absorption coefficient (mmꢁ1
F(000)
)
Crystal size (mm3)
Theta range (°)
Reflections collected
Independent reflections [R(int)]
Completeness (%)
5081 (0.0562)
99.0
Absorption correction
Max., min. transmission
Refinement method
Multi-scan
0.5281 and 0.4506
F2
Data/restraints/parameters
5081/0/325
0.981
Goodness-of-fit on F2
Final R indices [I>2sigma(I)]
R indices (all data)
0.0289, 0.0585
0.0445, 0.0624
Absolute structure parameter
Largest diff. peak and hole (e Åꢁ3
)
0.907 and ꢁ0.927
m, Ph); 7.30–7.13 (4H, m, Ph); 4.72 (1H, d, JHH = 1.5 Hz, subst Cp);
4.41 (1H, t, JHH = 1 Hz, subst Cp); 4.10 (1H, dd(ABX), JHH = 13 Hz,
JHP = 3 Hz, CH2Cp); 4.01 (5H, s, Cp); 3.87 (1H, t, JHH = 1 Hz, subst
Cp); 3.72 (1H, d(AB), JHH = 13 Hz, CH2Cp); 2.45 (1H, dq, JHH = 7.6 Hz,
JHP = 3 Hz, CH2CH3); 1.10 (1H, t, JHH = 7.6 Hz, CH2CH3). 31P{1H} NMR
(d, 202.8 MHz, CDCl3): ꢁ21.5.
cryostream of either an Oxford-Diffraction XCALIBUR CCD dif-
fractometer for 2a-Dia1, 2a-Dia2, 2b-Dia1, and 3a-Dia2 or on a
Stoe IPDS diffractometer for 2c-Dia1, 2c-Dia2, and 4a. Data were
collected using the monochromatic MoKa radiation (k = 0.71073).
The structures were solved by direct methods (SIR9722) and re-
fined by least-squares procedures on F2 using SHELXL-97.23 All
H atoms attached to carbon were introduced in calculation in
idealized positions and treated as riding models. The drawing
of the molecules was realized with the help of ORTEP32.24 The
molecular fitting of 2c-Dia2A and 2c-Dia2B has be realised with
the help of PLATON.25 Crystal data and refinement parameters
are shown in Table 2.
4.12. (RFc,SS)/(SFc,RS)-2-Diphenylphosphino-(tert-butylsulfoxy-
methyl)ferrocene 3c-Dia1
In
a Schlenk tube under argon were introduced 50 mg
(0.096 mmol) of the sulfoxide compound (RFc,SS)/(SFc,RS)-2c-Dia1
in 5 ml of toluene and 0.1 ml (90 g, 0.55 mmol) of tris(dimethyl-
amino)phosphine. After refluxing for 2 h, the solvent was removed
and the crude reaction product was purified by column chromatog-
raphy on silica using a degassed ether/dichloromethane mixture
(1/1) as the eluent. The sulfoxide phosphine product (RFc,SS)/
(SFc,RS)-3c-Dia1 was obtained as an orange liquid (yield: 36 mg,
76%).1H NMR (d, 500 MHz, CDCl3): 7.58–7.42 (2H, m, Ph); 7.43–
7.32 (3H, m, Ph); 7.30–7.18 (3H, m, Ph); 7.18–7.05 (2H, m, Ph);
4.79 (1H, s broad, subst Cp); 4.34 (1H, t, JHH = 1 Hz, subst Cp);
4.08 (5H, s, Cp); 3.82 (1H, t, JHH = 1 Hz, subst Cp); 3.73 (1H,
dd(ABX), JHH = 12 Hz, JHP = 2 Hz, CH2Cp); 3.30 (1H, d(AB),
JHH = 12 Hz, CH2Cp); 1.2 (9H, s, C(CH3)3). 31P{1H} NMR (d,
202.8 MHz, CDCl3): ꢁ20.6.
Full crystallographic data for the crystal structures herein have
been deposited with the Cambridge Crystallographic Data Centre
as supplementary publications CCDC 927621 for 2a-Dia1, 927622
for 2a-Dia2, 927623 for 2b-Dia1, 927624 for 2c-Dia1, 927625 for
2c-Dia2, 927626 for 3a-Dia2, and 927627 for (RFc,RS)-4a. These
data can obtained free of charge on application to CCDC, 12, Union
Road, Cambridge CB2 1EZ, UK; fax: +44 (1223)336033; or e-mail:
deposit@ccdc.cam.ac.uk.
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Following the same procedure described above for the desulfur-
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70 mg (0.135 mmol) of the sulfoxide compound (RFc,RS)/(SFc,SS)-
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7.28–7.12 (5H, m, Ph); 4.78 (1H, d, JHH = 2 Hz, subst Cp); 4.38
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JHP = 2 Hz, CH2Cp); 4.04 (5H, s, Cp); 3.75 (1H, d, JHH = 1 Hz, subst
Cp); 3.36 (1H, d(AB), JHH = 13 Hz, CH2Cp); 1.05 (9H, s, C(CH3)3).
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