Novel monodentate phosphoramidites by chiral pool synthesis starting from D-mannitol, and their PdII and RhI complexes

Article abstract of DOI:10.1002/1099-0682(20021)2002:1<199::AID-EJIC199>3.0.CO;2-H

The new monodentate phosphoramidites 6a-e were prepared in an ex-chiral-pool synthesis from readily available D-mannitol in high yields. A ring opening of 1,2;5,6-dianhydro-3,4-0-isopropylidene-D-mannitol (4) with nucleophiles provides the chiral diols 5a-e with different steric demand as key intermediates. The ligands 6a-e are synthesized by refluxing 5a-e with hexamethyltriaminophosphane (HMTAP) and lead, after treatment with [PdCl₂(COD)] or [Rh(COD)₂][SO₃CF₃], to the corresponding Pd. complex 8a and rhodium(I) complexes 7a-e, respectively. The cis-arrangement of the ligands and the C₂-symmetry of the complexes in the solid state is demonstrated by an X-ray structure investigation performed on 8a. In addition, variable temperature NMR experiments show that 8a keeps its C₂-symmetric coordination geometry even at temperatures up to 90°C (decomposition).

Full text of DOI:10.1002/1099-0682(20021)2002:1<199::AID-EJIC199>3.0.CO;2-H

FULL PAPER
Novel Monodentate Phosphoramidites By Chiral Pool Synthesis Starting from
D
-Mannitol, and Their PdII and RhI Complexes
Alexander Bayer,[a] Ulf Thewalt,[b] and Bernhard Rieger*[a]
Keywords: Asymmetric synthesis / Chiral pool / Rhodium / P ligands / Palladium
The new monodentate phosphoramidites 6a−e were pre-
pared in an ex-chiral-pool synthesis from readily available
mannitol in high yields. A ring opening of 1,2;5,6-dianhydro-
3,4-O-isopropylidene-
vides the chiral diols 5a−e with different steric demand as
key intermediates. The ligands 6a−e are synthesized by re- ments show that 8a keeps its C2-symmetric coordination geo-
[SO3CF3], to the corresponding Pd complex 8a and rhodium(I)
D
-
complexes 7a−e, respectively. The cis-arrangement of the li-
gands and the C2-symmetry of the complexes in the solid
D
-mannitol (4) with nucleophiles pro- state is demonstrated by an X-ray structure investigation per-
formed on 8a. In addition, variable temperature NMR experi-
fluxing 5a−e with hexamethyltriaminophosphane (HMTAP)
metry even at temperatures up to 90 °C (decomposition).
and lead, after treatment with [PdCl2(COD)] or [Rh(COD)2]-
We report here on a straightforward and highly variable
synthetic protocol based on an ex-chiral-pool synthesis
starting from -mannitol[6] to generate monodentate phos-
phoramidites bearing four stereogenic centers. This ap-
proach allows us to introduce a variety of substituents with
different steric demand at key positions at the stereogenic
centers by using selected nucleophiles in epoxide ring-open-
ing reactions. The structure and dynamic behavior of the
corresponding PdII and RhI complexes was investigated by
a combination of X-ray diffraction in the solid state and
variable temperature NMR spectroscopy in solution.
Introduction
Worldwide activity in the development of C2-symmetric,
bridged bisphosphane complexes for asymmetric catalyzed
reactions began in the late 1970’s and continued strongly
until the end of the 1980’s. Then, major emphasis was spent
on the development of biocatalysts for catalytic organic
transformations. It is well known that both enzymes and
organometallic complexes occupy their own specific cata-
lytic field. In organometallic chemistry bidentate ligands
were supposed to be superior to the monodentate ones as
the resulting rigidity of the catalysts favors effective chiral
induction.[1] Consequently, monodentate ligands were neg- Results and Discussion
lected in asymmetric hydrogenations until Pringle et al.
The starting material for our synthetic strategy is the
questioned the superiority of bidentate structures. These
authors found higher enantioselectivities (92% ee) using an
asymmetric monophosphonite rather then the correspond-
ing C2-symmetric diphosphonite in the hydrogenation of
methyl-2-acetamido acrylate.[2] Excellent enantioselectivi-
ties (Ͼ99% ee) have also been reported with monodentate
phosphites[3] and phosphoramidites,[4,5] inducing a renais-
sance in the investigation of monodentate ligands of the
above type. However, a disadvantage of these species is their
limitation to the binaphthol backbone, which does not al-
low a rational catalyst design.
commercially available and cheap -mannitol (1), which
was converted into the 1,2;3,4;5,6-tri-O-isopropylidene de-
rivative (2). Subsequent acidic cleavage of two protecting
groups yielded the 3,4-O-isopropylidene--mannitol (3) se-
lectively.[7,8]
1,2;5,6-Dianhydro-3,4-O-isopropylidene--
mannitol (4) was prepared from 3 in a simple one pot syn-
thesis according to a literature procedure.[9] The stereoiso-
mer 1,2;5,6-dianhydro-3,4-O-isopropylidene--iditol,[7] with
a different configuration at carbon atoms C2 and C5, is
also available and provides access to additional chiral diols.
Ring-opening reactions using organolithium or Grignard
compounds afford the chiral key-diols 5aϪe. Nucleophilic
attack of LiAlH4 opens the epoxide ring to form
(2R,3R,4R,5R)-3,4-O-isopropylidene-2,3,4,5-hexanetetraol
(5a).[10] Compounds 5bϪe were prepared by treatment with
[a]
Department of Inorganic Chemistry II, Materials and Catalysis,
University of Ulm
Albert-Einstein-Allee 11, 89069 Ulm, Germany
Fax: (internat.) ϩ 49-731/502-3039
E-mail: bernhard.rieger@chemie.uni-ulm.de
organocuprates
Ϫ
generated from the copper(I)
[b]
Section for X-ray- and electron diffraction, University of Ulm
Albert-Einstein-Allee 11, 89069 Ulm, Germany
bromideϪdimethyl sulfide complex Ϫ and the correspond-
Eur. J. Inorg. Chem. 2002, 199Ϫ203
WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002
1434Ϫ1948/02/0101Ϫ0199 $ 17.50ϩ.50/0
199

A. Bayer, U. Thewalt, B. Rieger
FULL PAPER
Figure 1. a) acetone, H2SO4; b) AcOH, H2O, 40 °C; c) (i) trimethyl orthoacetate, PPTS, (ii) NEt3, AcBr, (iii) K2CO3, MeOH; d) LiAlH4,
Et2O, R ϭ H; e) CuBr·SMe2, RMgBr, THF/Et2O, Ϫ40 °C, R ϭ CH3, C2H5, i-C4H9, C6H5; f) HMTAP, toluene, reflux; g) RhI(COD)2-
(SO3CF3), CH2Cl2, 7aϪe: M ϭ Rh, L1-L2 ϭ COD; h) PdII(COD)Cl2, CH2Cl2, 8a: M ϭ Pd; L1,L2 ϭ Cl
ing alkyl- or phenylmagnesium bromides in diethyl ether.[11] the absolute configuration of hydrogenation products from
The monodentate phosphoramidites (6aϪe) were formed in the chiral cage of the catalyst.[12] We are looking forward to
high yields by refluxing 5aϪe and HMTAP in toluene check these predictions in applying 7aϪe in the asymmetric
(Figure 1).
hydrogenation of prochiral olefins. The rigidity of the C2-
The corresponding yellow-orange RhI complexes 7aϪe symmetric ligand arrangement in solution is further sup-
and the pale yellow PdII complex 8a were prepared by stir- ported by variable temperature 31P NMR spectroscopy. The
ring two equivalents of monodentate ligand 6aϪe with spectra of 8a show a sharp singlet at δ ϭ 102.49, which
[Rh(COD)2][SO3CF3] or [PdCl2(COD)] in dichlorome- remains unaltered between Ϫ30 °C and ϩ90 °C (decom-
thane.
position). The RhI complexes 7aϪe have 31P NMR spectra
We were not able to obtain suitable crystals of one of the with a single sharp doublet. Variable temperature NMR ex-
rhodium(I) complexes for X-ray diffraction, but we suc- periments performed on 7a show an unaltered signal at δ ϭ
ceeded in crystallizing the isoelectronic PdII species 8a from 118.92 between Ϫ30 °C and ϩ60 °C, which again indicates
methanol. Its X-ray structure clearly shows the cis-coor- the presence of a single isomer. At higher temperatures a
dination of the two monodentate phosphoramidite ligands second doublet grows at δ ϭ 86.67, which could be due to
6a and the expected square-planar coordination environ- a further complex species. This second species undergoes
ment of PdII (Figure 2a, Table 1) with a chiral, C2-symmet- decomposition, as we noticed from a NMR measurement
ric arrangement of both P ligands (Figure 2b).
the next day, while the initial RhI complex is still present.
No sign of other diastereomers (rotamers) could be
found, indicating a stable chiral conformation, at least in
the solid state. The side-view (Figure 2b) furthermore shows
that the tunable substituents (Figure 1, CH2ϪR) of the
monodentate phosphoramidites (Figure 2, R ϭ H; C1, C10)
Conclusion
We have introduced an efficient, ex-chiral-pool synthetic
occupy the top-left and bottom-right quadrants, thus defin- route to a new family of chiral, monodentate phosphorus
ing a chiral cage around the metal center, the size of which ligands with different steric demand. Their corresponding
is determined by the nucleophile used for the epoxide ring- C2-symmetric RhI and PdII complexes bear two cis-ar-
opening. Quadrant diagrams have often been used to ex- ranged ligands both in the solid state and in solution. In
plain the achieved enantioselectivity with several known addition, the complexes are thermally stable up to 60 and
asymmetric diphosphane-rhodium catalysts in hydrogena- 90 °C, respectively. Due to the variability of the ligand syn-
tions. Knowles suggested to use X-ray structures to predict thesis, changes of the configuration of the stereogenic cen-
200
Eur. J. Inorg. Chem. 2002, 199Ϫ203

Novel Monodentate Phosphoramidites and Their PdII and RhI Complexes
FULL PAPER
˚
Table 1. Selected bond lengths [A] and angles [°] in 8a
Bond lengths
PdϪCl1
PdϪCl2
PdϪP1
PdϪP2
P1ϪO1
P1ϪO2
P1ϪN1
N1ϪC19
N1ϪC20
O1ϪC5
O2ϪC2
2.3461(9)
2.3416(10)
2.2462(9)
2.2360(9)
1.592(2)
1.6082(18)
1.620(3)
1.474(4)
1.461(4)
1.459(3)
1.462(3)
C1ϪC2
C2ϪC3
C3ϪC4
C4ϪC5
C5ϪC6
C7ϪC8
C8ϪC9
O3ϪC3
O3ϪC8
O4ϪC4
O4ϪC8
1.500(4)
1.510(4)
1.507(4)
1.519(4)
1.503(5)
1.495(5)
1.513(5)
1.419(3)
1.438(4)
1.422(4)
1.447(4)
Bond angles
Cl1ϪPdϪCl2
P1ϪPdϪCl1
P1ϪPdϪP2
P2ϪPdϪCl2
P1ϪPdϪCl2
P2ϪPdϪCl1
PdϪP1ϪO1
PdϪP1ϪO2
PdϪP1ϪN1
O1ϪP1ϪO2
O1ϪP1ϪN1
O2ϪP1ϪN1
P1ϪN1ϪC19
P1ϪN1ϪC20
C19ϪN1ϪC20
P1ϪO1ϪC5
P1ϪO2ϪC2
C1ϪC2ϪO2
C3ϪC2ϪO2
88.90(3)
86.92(3)
93.05(3)
91.16(3)
175.49(3)
179.10(3)
117.44(8)
112.22(7)
113.58(9)
103.26(11)
103.78(13)
105.27(13)
120.8(2)
C1ϪC2ϪC3
C2ϪC3ϪC4
C2ϪC3ϪO3
C3ϪO3ϪC8
O3ϪC3ϪC4
O3ϪC8ϪC7
O3ϪC8ϪC9
O3ϪC8ϪO4
C7ϪC8ϪC9
C7ϪC8ϪO4
C9ϪC8ϪO4
C8ϪO4ϪC4
O4ϪC4ϪC5
O4ϪC4ϪC3
C3ϪC4ϪC5
C4ϪC5ϪC6
C4ϪC5ϪO1
O1ϪC5ϪC6
113.4(2)
115.7(2)
111.3(2)
105.7(2)
101.7(2)
107.7(3)
110.1(3)
105.8(2)
114.3(3)
110.4(3)
108.2(3)
107.1(2)
111.3(2)
101.1(2)
116.4(3)
113.8(3)
108.4(2)
105.8(2)
122.9(2)
116.2(3)
129.59(18)
121.45(18)
108.6(3)
104.1(2)
13C, and 31P NMR spectra were recorded on Bruker DRX 400
spectrometer. Chemical shifts are reported in ppm downfield from
tetramethylsilane with the solvent as the internal standard or 85%
H3PO4 as the external standard.
Figure 2. Molecular structure of 8a; (a) front view: square-planar
environment of PdII; (b) side view: C2-symmetric arrangement; hy-
drogen atoms have been omitted for clarity
ters (Figure 2, C2, C5 and C11, C14) and modifications of
their substitution can easily be introduced. This is a pre-
requisite for adopting the catalysts to new substrates in
asymmetric transformations. Investigations on this topic
are underway.
Synthesis of Chiral Diols 5aϪe: The diols 5a and 5b were prepared
according to known procedures.[10,11]
General Procedure for the Synthesis of 5cϪe: CuBr·SMe2 (3 mmol)
was added to a stirred suspension of the appropriate alkyl- or
phenylmagnesium bromide (120 mmol) in diethyl ether (100 mL)
at Ϫ40 °C. After stirring at Ϫ40 °C for 2 h, 4 (30 mmol) in 30 mL
tetrahydrofuran was added. After 1 h stirring at room temperature
the mixture was poured into a saturated aqueous NH4Cl solution.
The organic layer was extracted, washed with water, dried over
Na2SO4 and the solvents evaporated to dryness to give the pure
products (5cϪe) after flash chromatography (eluting with hexane/
EtOAc; 7:3).
Experimental Section
General Remarks: All reactions and manipulations were performed
using standard Schlenk techniques. The reagents were obtained
from Aldrich, Fluka, Merck and Strem and used without purifica-
tion. Diethyl ether, tetrahydrofuran, toluene and pentane were dis-
tilled from LiAlH4, dichloromethane was distilled from CaH2 un-
der nitrogen.
(4R,5R,6R,7R)-5,6-O-isopropylidene-4,5,6,7-decanetetraol (5c): Oil.
Yield: 6.78 g, 91.8%. [α]2D3 ϭ ϩ25.8 (c ϭ 1.0, CHCl3). 1H NMR
(400 MHz, CDCl3): δ ϭ 3.61Ϫ3.59 (m, 2 H, CH), 3.55Ϫ3.49 (m,
Melting points were determined on a Büchi Melting Point B-540
and are uncorrected. Optical rotation was obtained on a POLAR- 2 H, CH), 1.74Ϫ1.66 (m, 2 H, CH2), 1.58Ϫ1.45 (m, 2 H, CH2),
monitor from IBZ Messtechnik. Elemental analyses were carried
out on a Elementar Vario EL. Mass spectrometry was performed
1.45Ϫ1.33 (m, 4 H, CH2), 1.32 (s, 6 H, CH3), 0.91 (t, 6 H, CH3).
13C NMR: δ ϭ 108.67, 83.24, 72.88, 36.34, 26.85, 18.26, 14.00. MS
on a Finnigan MAT, TSQ 7000 (FAB, matrix: 2-nitrophenyloctyl (CI): MHϩ ϭ 391 (ϩMSTFA). C13H26O4 (246.3): calcd. C 63.39,
1
ether) and a Finnigan MAT, SSQ 7000 (CI: CH4. EI: 70 eV). H,
H 10.64; found C 62.68, H 10.60.
Eur. J. Inorg. Chem. 2002, 199Ϫ203
201

A. Bayer, U. Thewalt, B. Rieger
FULL PAPER
(5R,6R,7R,8R)-6,7-O-isopropylidene-2,11-dimethyl-5,6,7,8-dode- (m, 12 H, CH3). 13C NMR: δ ϭ 109.30, 82.88, 82.61, 75.79, 74.60,
canetetraol (5d): Oil. Yield: 8.63 g, 95.1%. [α]2D4 ϭ ϩ29.2 (c ϭ 1.0,
34.16, 33.97, 33.17, 32.97, 31.44, 31.41, 30.26, 30.19, 27.00, 25.97,
CHCl3). 1H NMR (400 MHz, CDCl3): δ ϭ 3.65Ϫ3.63 (m, 2 H, 25.89, 21.82, 21.45. 31P NMR: δ ϭ 140.83 (s). MS (CI): MHϩ
CH), 3.55Ϫ3.48 (m, 2 H, CH), 1.80Ϫ1.71 (m, 2 H, CH2), 376. C19H38NO4P (375.5): calcd. C 60.78, H 10.20, N 3.73; found
ϭ
1.60Ϫ1.50 (m, 2 H, CH2), 1.44Ϫ1.35 (m, 4 H, CH2), 1.34 (s, 6 H, C 58.54, H 10.10, N 4.28.
CH3), 1.28Ϫ1.18 (m, 2 H, CH), 0.89Ϫ0.86 (m, 12 H, CH3). 13C
NMR: δ ϭ 108.72, 83.16, 73.48, 34.20, 32.06, 28.11, 26.90, 22.81,
22.38. MS (CI): MHϩ ϭ 447 (ϩMSTFA). C17H34O4 (302.5): calcd.
C 67.51, H 11.33; found C 66.37, H 10.97.
(4R,5S,6S,7R)-5,6-O-isopropylidene-2-dimethylamino-4,7-dibenzyl-
1,3,2-dioxaphosphepane-5,6-diol (6e): Yield: 2.61 g, 96.7%; mp: 64
1
°C. [α]2D3ϭ ϩ29.5 (c ϭ 1.0, CHCl3). H NMR (400 MHz, CDCl3):
δ ϭ 7.24Ϫ7.12 (m, 10 H, CHarom.), 4.02Ϫ3.96 (m, 1 H, CH),
3.93Ϫ3.88 (m, 2 H, CH), 3.51Ϫ3.47 (m, 1 H, CH), 3.09Ϫ3.00 (m,
2 H, CH2), 2.90Ϫ2.82 (m, 2 H, CH2), 2.40 (s, 3 H, NϪCH3), 2.38
(s, 3 H, NϪCH3), 1.41 (s, 3 H, CH3), 1.39 (s, 3 H, CH3). 13C NMR:
δ ϭ 137.78, 137.31, 130.24, 129.99, 127.88, 127.70, 126.16, 126.11,
109.58, 81.46, 81.16, 75.83, 74.05, 40.27, 39.18, 35.01, 34.88, 27.01,
26.89. 31P NMR: δ ϭ 141.30 (s). MS (CI): MHϩ ϭ 416.
C23H30NO4P (415.5): calcd. C 66.49, H 7.28, N 3.37; found C
64.02, H 7.33, N 4.22.
(2R,3R,4R,5R)-3,4-O-Isopropylidene-1,6-diphenyl-2,3,4,5-hexa-
netetraol (5e): Oil. Yield: 9.20 g, 89.6%. [α]2D3 ϭ ϩ43.2 (c ϭ 1.0,
CHCl3). 1H NMR (400 MHz, CDCl3): δ ϭ 7.33Ϫ7.20 (m, 10 H,
CHarom.), 3.82Ϫ3.72 (m, 4 H, CH), 3.18Ϫ3.13 (m, 2 H, CH2),
2.74Ϫ2.68 (m, 2 H, CH2), 1.48 (s, 6 H, CH3). 13C NMR: δ ϭ
137.66, 129.68, 128.39, 126.42, 109.02, 82.34, 73.54, 40.26, 26.93.
MS (CI): MHϩ ϭ 343 (ϩMSTFA). C21H26O4 (342.4): calcd. C
73.66, H 7.65; found C 72.56, H 7.63.
Synthesis of Rhodium(I) Complexes. General Procedure for the Syn-
thesis of 7aϪe: A solution of 2 equivalents of the corresponding
monodentate phosphoramidite 6aϪe in 20 mL dichloromethane
was added to a stirred solution of [Rh(COD)2][SO3CF3] (300 mg,
0.64 mmol) in 30 mL of dichloromethane at 0 °C. After stirring for
2 h at room temperature, the solvent was removed under reduced
pressure. The resulting orange solid was washed twice with 50 mL
pentane and dried in vacuo.
General Procedure for the Synthesis of 6aϪe: Chiral diols 5aϪe
(6.5 mmol), HMTAP (8.23 mmol) and 10 mg NH4Cl were refluxed
in toluene for 7 h. The mixture was concentrated under reduced
pressure affording an oil. The oil was stirred in a small amount of
diethyl ether, after which crystals formed.
(4R,5S,6S,7R)-5,6-O-Isopropylidene-2-dimethylamino-4,7-dimethyl-
1,3,2-dioxaphosphepane-5,6-diol (6a): Yield: 1.66 g, 97.2%; m.p. 70
1
°C. [α]2D3ϭ ϩ10.2 (c ϭ 1.0, CHCl3). H NMR (400 MHz, CDCl3):
{Bis[(4R,5S,6S,7R)-5,6-O-isopropylidene-2-dimethylamino-4,7-di-
methyl-1,3,2-dioxaphosphepane]Rh(COD)} Trifluoromethanesulfo-
nate (7a): Yield: 557 mg, 98.2%. 1H NMR (400 MHz, CDCl3): δ ϭ
5.53Ϫ5.45 (m, 2 H, CHCOD), 5.19Ϫ5.11 (m, 2 H, CHCOD),
4.33Ϫ4.23 (m, 2 H, CH), 4.09Ϫ3.99 (m, 2 H, CH), 3.42Ϫ3.36 (m,
2 H, CH), 3.30Ϫ3.24 (m, 2 H, CH), 3.03Ϫ2.98 (m, 12 H, NϪCH3),
2.77Ϫ2.31 (m, 8 H, CH2 COD), 1.39 (s, 6 H, CH3), 1.36 (s, 6 H,
CH3), 1.33 (d, 6 H, CH3), 1.29 (d, 6 H, CH3). 31P NMR: δ ϭ
δ ϭ 3.95Ϫ3.85 (m, 3 H, CH), 3.53Ϫ3.48 (m, 1 H, CH), 2.58 (s, 3
H, NϪCH3), 2.56 (s, 3 H, NϪCH3), 1.38 (d, 3 H, CH3), 1.34 (s, 6
H, CH3), 1.33 (d, 3 H, CH3). 13C NMR: δ ϭ 109.30, 83.72, 83.59,
72.39, 71.16, 35.00, 34.81, 26.95, 21.25, 19.98. 31P NMR: δ ϭ
142.71 (s). MS (CI): MHϩ ϭ 264. C11H22NO4P (263.3): calcd. C
50.18, H 8.42, N 5.32; found C 49.16, H 8.35, N 5.40.
(4R,5S,6S,7R)-5,6-O-isopropylidene-2-dimethylamino-4,7-diethyl-
1,3,2-dioxaphosphepane-5,6-diol (6b): Yield: 1.77 g, 93.7%; m.p. 44
118.92 (d). MS (FAB): [M
Ϫ
SO3CF3Ϫ]ϩ
ϭ
737.
1
°C. [α]2D3ϭ ϩ31.3 (c ϭ 1.0, CHCl3). H NMR (400 MHz, CDCl3):
C31H56F3N2O11P2RhS (886.7): calcd. C 41.99, H 6.37, N 3.16;
found C 41.42, H 5.97, N 3.18.
δ ϭ 3.86Ϫ3.70 (m, 3 H, CH), 3.60Ϫ3.55 (m, 1 H, CH), 2.60 (s, 3
H, NϪCH3), 2.57 (s, 3 H, NϪCH3), 1.88Ϫ1.73 (m, 2 H, CH2),
1.66Ϫ1.51 (m, 2 H, CH2), 1.34 (s, 3 H, CH3), 1.33 (s, 3 H, CH3),
0.97 (t, 3 H, CH3), 0.95 (t, 3 H, CH3). 13C NMR: δ ϭ 109.29,
82.34, 82.10, 76.68, 75.17, 35.09, 34.89, 27.48, 26.91, 26.31, 9.26,
{Bis[(4R,5S,6S,7R)-5,6-O-isopropylidene-2-dimethylamino-4,7-
diethyl-1,3,2-dioxaphosphepane]Rh(COD)} Trifluoromethanesulfon-
1
ate (7b): Yield: 477 mg, 79.1%. H NMR (400 MHz, CDCl3): δ ϭ
5.60Ϫ5.53 (m, 2 H, CHCOD), 5.32Ϫ5.25 (m, 2 H, CHCOD),
4.09Ϫ3.98 (m, 4 H, CH), 3.59Ϫ3.52 (m, 2 H, CH), 3.39Ϫ3.32 (m,
2 H, CH), 3.06Ϫ3.01 (m, 12 H, NϪCH3), 2.76Ϫ2.33 (m, 8 H, CH2
COD), 1.86Ϫ1.77 (m, 4 H, CH2), 1.77Ϫ1.66 (m, 2 H, CH2),
1.55Ϫ1.43 (m, 2 H, CH2), 1.40 (s, 6 H, CH3), 1.37 (s, 6 H, CH3),
0.99Ϫ0.91 (m, 12 H, CH3). 31P NMR: δ ϭ 118.06 (d). MS (FAB):
[M Ϫ SO3CF3Ϫ]ϩ ϭ 793. C35H64F3N2O11P2RhS (942.8): calcd. C
44.59, H 6.84, N 2.97; found C 45.12, H 6.97, N 2.97.
8.83. 31P NMR:
δ ϭ 292.
ϭ 141.72 (s). MS (CI): MHϩ
C13H26NO4P (291.3): calcd. C 53.60, H 9.00, N 4.81; found C
51.59, H 9.02, N 5.04.
(4R,5S,6S,7R)-5,6-O-Isopropylidene-2-dimethylamino-4,7-dipropyl-
1,3,2-dioxaphosphe-pane-5,6-diol (6c): yield: 1.94 g, 93.6%; m.p. 87
1
°C. [α]2D3ϭ ϩ36.8 (c ϭ 1.0, CHCl3). H NMR (400 MHz, CDCl3):
δ ϭ 3.88Ϫ3.76 (m, 3 H, CH), 3.58Ϫ3.54 (m, 1 H, CH), 2.59 (s, 3
H, NϪCH3), 2.57 (s, 3 H, NϪCH3), 1.79Ϫ1.65 (m, 2 H, CH2),
1.64Ϫ1.46 (m, 4 H, CH2), 1.44Ϫ1.35 (m, 2 H, CH2), 1.35 (s, 3 H,
CH3), 1.34 (s, 3 H, CH3), 0.91 (t, 3 H, CH3), 0.90 (t, 3 H, CH3).
13C NMR: δ ϭ 109.32, 82.80, 82.62, 75.35, 74.04, 36.70, 35.46,
35.15, 34.95, 26.94, 26.87, 18.29, 17.89, 13.97. 31P NMR: δ ϭ
141.10 (s). MS (CI): MHϩ ϭ 320. C15H30NO4P (319.4): calcd. C
56.41, H 9.47, N 4.39; found C 54.43, H 9.30, N 4.73.
{Bis[(4R,5S,6S,7R)-5,6-O-isopropylidene-2-dimethylamino-4,7-di-
propyl-1,3,2-dioxaphosphepane]Rh(COD)} Trifluoromethanesulfon-
1
ate (7c): Yield: 558 mg, 87.2%. H NMR (400 MHz, CDCl3): δ ϭ
5.55Ϫ5.46 (m, 2 H, CHCOD), 5.29Ϫ5.21 (m, 2 H, CHCOD),
4.10Ϫ3.98 (m, 4 H, CH), 3.55Ϫ3.47 (m, 2 H, CH), 3.32Ϫ3.27 (m,
2 H, CH), 3.03Ϫ2.97 (m, 12 H, NϪCH3), 2.74Ϫ2.32 (m, 8 H, CH2
COD), 1.79Ϫ1.63 (m, 4 H, CH2), 1.61Ϫ1.50 (m, 2 H, CH2),
1.49Ϫ1.39 (m, 6 H, CH2), 1.38 (s, 6 H, CH3), 1.35 (s, 6 H, CH3),
1.33Ϫ1.20 (m, 4 H, CH2),0.94Ϫ0.87 (m, 12 H, CH3). 31P NMR:
(4R,5S,6S,7R)-5,6-O-Isopropylidene-2-dimethylamino-4,7-di-iso-
pentyl-1,3,2-dioxaphosphe-pane-5,6-diol (6d): Yield: 2.33 g, 95.3%;
δ
ϭ 117.93 (d). MS (FAB): [M Ϫ ϭ 849.
SO3CF3Ϫ]ϩ
1
mp: 67 °C. [α]2D3ϭ ϩ37.5 (c ϭ 1.0, CHCl3). H NMR (400 MHz,
C39H72F3N2O11P2RhS (998.9): calcd. C 46.89, H 7.26, N 2.80;
found C 46.38, H 7.11, N 2.87.
CDCl3): δ ϭ 3.83Ϫ3.72 (m, 3 H, CH), 3.58Ϫ3.53 (m, 1 H, CH),
2.59 (s, 3 H, NϪCH3), 2.56 (s, 3 H, NϪCH3), 1.83Ϫ1.70 (m, 2 H,
CH), 1.61Ϫ1.46 (m, 4 H, CH2), 1.45Ϫ1.35 (m, 2 H, CH2), 1.35 (s, {Bis[(4R,5S,6S,7R)-5,6-O-isopropylidene-2-dimethylamino-4,7-di-
3 H, CH3), 1.34 (s, 3 H, CH3), 1.27Ϫ1.18 (m, 2 H, CH2), 0.88Ϫ0.85 iso-pentyl-1,3,2-dioxaphosphepane]Rh(COD)} Trifluoromethanesul-
202
Eur. J. Inorg. Chem. 2002, 199Ϫ203

Novel Monodentate Phosphoramidites and Their PdII and RhI Complexes
FULL PAPER
fonate (7d): Yield: 692 mg, 97.3%. 1H NMR (400 MHz, CDCl3):
δ ϭ 5.55Ϫ5.48 (m, 2 H, CHCOD), 5.32Ϫ5.25 (m, 2 H, CHCOD), (s, 12 H, CH3), 1.36 (d, 6 H, CH3). 13C NMR: δ ϭ 110.05, 83.61,
4.11Ϫ3.96 (m, 4 H, CH), 3.54Ϫ3.48 (m, 2 H, CH), 3.36Ϫ3.30 (m,
82.38, 74.13, 37.08, 26.75, 26.55, 18.89, 18.82. 31P NMR: δ ϭ
2 H, CH), 3.03Ϫ2.97 (m, 12 H, NϪCH3), 2.75Ϫ2.32 (m, 8 H, CH2 102.49 (s). MS (FAB): [M 669.
SO3CF3Ϫ]ϩ
COD), 1.81Ϫ1.69 (m, 4 H, CH2), 1.68Ϫ1.58 (m, 2 H, CH), C22H44Cl2N2O8P2Pd (703.9): calcd. C 37.54, H 6.30, N 3.98; found
2 H, CH), 2.92Ϫ2.89 (m, 12 H, NϪCH3), 1.47 (d, 6 H, CH3), 1.37
Ϫ
ϭ
1.57Ϫ1.46 (m, 4 H, CH2), 1.45Ϫ1.40 (m, 2 H, CH), 1.39 (s, 6 H, C 36.80, H 6.34, N 4.09.
CH3), 1.36 (s, 6 H, CH3), 1.32Ϫ1.11 (m, 8 H, CH2), 0.91Ϫ0.82
X-ray Crystallography of 8a: The crystal used in this study was
mounted onto the end of an glass fiber. X-ray data were collected
(m, 24 H, CH3). 31P NMR: δ ϭ 118.01 (d). MS (FAB): [M Ϫ
SO3CF3Ϫ]ϩ ϭ 961. C47H88F3N2O11P2RhS (1111.1): calcd. C 50.81,
H 7.98, N 2.52; found C 50.35, H 7.91, N 2.68.
at Ϫ100 °C on a STOE IPDS unit (Imaging Plate Diffraction Sys-
˚
tem). Graphite monochromated Mo-Kα radiation (λ ϭ 0.71073 A)
was used. Crystal data are listed in Table 2 together with refinement
details. Absorption corrections were not applied. The structure was
solved by the Patterson method with the SHELXS-86 program.[13]
The atomic coordinates and anisotropic thermal parameters of the
non-hydrogen atoms were refined using the SHELXL-97 pro-
gram;[14] full-matrix method, F2 data. Hydrogen atoms were in-
cluded in the final refinement cycles in a riding mode.
Crystallographic data (excluding structure factors) for the struc-
ture(s) included in this paper have been deposited with the Cam-
bridge Crystallographic Data Centre as supplementary publication
no. CCDC-165693. Copies of the data can be obtained free
of charge on application to CCDC, 12 Union Road, Cambridge
{Bis[(4R,5S,6S,7R)-5,6-O-ispropylidene-2-dimethylamino-4,7-
dibenzyl-1,3,2-dioxaphosphe-pane]Rh(COD)} Trifluoromethanesul-
fonate (7e): Yield: 743 mg, 97.5%. 1H NMR (400 MHz, CDCl3):
δ ϭ 7.37Ϫ7.08 (m, 20 H, CHarom.), 5.47Ϫ5.39 (m, 2 H, CHCOD),
5.22Ϫ5.16 (m, 2 H, CHCOD), 4.44Ϫ4.38 (m, 2 H, CH), 4.13Ϫ4.05
(m, 2 H, CH), 3.53Ϫ3.48 (m, 2 H, CH), 3.17Ϫ3.10 (m, 2 H, CH),
2.75Ϫ2.33 (m, 8 H, CH2 COD), 2.52Ϫ2.47 (m, 12 H, NϪCH3),
1.50Ϫ1.45 (m, 2 H, CH2), 1.44 (s, 6 H, CH3), 1.43Ϫ1.36 (m, 2 H,
CH2), 1.32Ϫ1.24 (m, 2 H, CH2), 1.24 (s, 6 H, CH3), 1.23Ϫ1.15 (m,
2 H, CH2). 31P NMR: δ ϭ 118.35 (d). MS (FAB): [M Ϫ
SO3CFϪ33]ϩ ϭ 1041. C55H72F3N2O11P2RhS (1191.1): calcd. C 55.46,
H 6.09, N 2.35; found C 54.25, H 6.19, N 2.67.
CB2 1EZ, UK [Fax: (internat.)
deposit@ccdc.cam.ac.uk].
ϩ 44-1223/336-033; Email:
{Bis((4R,5S,6S,7R)-5,6-O-isopropylidene-2-dimethylamino-4,7-di-
methyl-1,3,2-dioxaphosphepane]}PdCl2 (8a): A solution of 2 equiva-
lents of monodentate ligand 6a in 50 mL dichloromethane was ad-
ded to a stirred solution of [PdCl2(COD)] (500 mg, 1.75 mmol) in
70 mL of dichloromethane at 0 °C. After stirring at room temper-
ature for 2 h, the solvent was removed under reduced pressure.
Washing the residue twice with 50 mL of diethyl ether and drying
in vacuo resulted in a pale yellow powder. Yield: 749 mg, 60.8%.
1H NMR (400 MHz, CDCl3): δ ϭ 4.82Ϫ4.73 (m, 2 H, CH),
4.38Ϫ4.31 (m, 2 H, CH), 3.64Ϫ3.60 (m, 2 H, CH), 3.49Ϫ3.45 (m,
Acknowledgments
We thank the Deutsche Forschungsgemeinschaft for financial sup-
port of this work (Ri613/5Ϫ1). Alexander Bayer was further sup-
ported by a scholarship of the state of Baden-Württemberg.
[1]
X. Zhang, Enantiomer 1999, 4, 541.
C. Claver, E. Fernandez, A. Gillon, K. Heslop, D. J. Hyett, A.
[2]
Martorell, A. G. Orpen, P. G. Pringle, Chem. Commun. 2000,
961Ϫ962.
[3]
M. T. Reetz, G. Mehler, Angew. Chem. 2000, 112, 4047Ϫ4049;
Table 2. Crystal data and refinement details for 8a
Angew. Chem. Int. Ed. 2000, 39, 3889Ϫ3891.
[4]
M. van den Berg, A. J. Minnaard, E. P. Schudde, J. van Esch,
8a
A. H. M. de Vries, J. G. de Vries, B. L. Feringa, J. Am. Chem.
Soc. 2000, 122, 11539Ϫ11540.
Phosphoramidites are also frequently used in the enantioselec-
[5]
Formula
Mr
C22H44Cl2N2O8P2Pd
703.83
tive copper-catalyzed conjugate addition of dialkylzinc reagents
to enones, see: A. Alexakis, G. P. Trevitt, G. Bernardinelli, J.
Am. Chem. Soc. 2001, 123, 4358Ϫ4359.
Crystal system
Space group
Monoclinic
P21
[6]
˚
a (A)
8.098(2)
14.460(2)
13.910(3)
96.06(3)
1619.6(6)
2
1.443
0.88
0.40 ϫ 0.30 ϫ 0.10
2.04Ϫ25.98
14673
-Mannitol is also the starting material for the synthesis of
˚
b (A)
bidentate ligands: A. Börner, J. Holz, G. Voss, R. Stürmer, DE
48 084 (18.06.1997); J. Holz, M. Quirmbach, U. Schmidt, D.
Heller, R. Stürmer, A. Börner, J. Org. Chem. 1998, 63,
8031Ϫ8034.
˚
c (A)
β (°)
V (A )
3
˚
[7]
Z
Y. Merrer, A. Dureault, C. Greck, D. Micas-Languin, C. Grav-
Dcalcd. (g·cmϪ3
)
ier, J. Depezay, Heterocycles 1987, 25, 541Ϫ548.
[8]
µ (mmϪ1
)
L. F. Wiggins, J. Chem. Soc. 1946, 13, 13Ϫ14.
[9]
Crystal size (mm3)
θ range (°)
B. B. Lohray, M. Chatterjee, Y. Jayamma, Synth. Commun.
1997, 27, 1711Ϫ1724.
[10]
Measured reflections
Unique reflections
Rint
L. F. Wiggins, D. J. C. Wood, J. Am. Chem. Soc. 1950,
5968
0.039
1566Ϫ1575.
[11]
P. Allevi, M. Anastasia, P. Ciuffreda, A. M. Sanvito, Tetrahed-
Reflections with I Ͼ 2σ(I)
Goodness-of-fit
R1 [F, I Ͼ 2σ(I)]
R1 (F, all data)
wR2 (F2, all data)
5543
1.01
0.025
0.029
0.053
Ϫ0.46/0.37
Ϫ0.03
ron: Asymmetry 1994, 5, 927Ϫ934.
[12]
W. S. Knowles, Acc. Chem. Res. 1983, 16, 106Ϫ112.
[13]
G. M. Sheldrick, SHELXS-86, Program for the Solution of
Crystal Structures, Göttingen, 1986.
G. M. Sheldrick, SHELXL-97, Program for the Refinement of
Crystal Structures, Göttingen, 1997.
Received June 27, 2001
[I01233]
[14]
Ϫ3
˚
Min./max. in ∆F (e·A
)
Absolute struct. parameter
Eur. J. Inorg. Chem. 2002, 199Ϫ203
203