Chiral mono- and bidentate ligands derived from D-mannitol and their application in rhodium(I)-catalyzed asymmetric hydrogenation reactions

Article abstract of DOI:10.1002/1099-0682(200210)2002:10<2614::AID-EJIC2614>3.0.CO;2-2

The new monodentate phosphoramidites 8a-g and bidentate phospholanes 13a-e are prepared in an ex-chiral-pool synthesis from D-mannitol. Chiral diols 7a-g, obtained via nucleophilic ring opening of bis(epoxides) 6a-b, are the key intermediates for the production of both classes of ligands. Treatment of 8a-g or 13a-e with [PdCl₂(COD)] or [Rh(COD)₂][-SO₃CF₃] yield the corresponding Pd (10a, 10f, 15a) and Rh compounds (9a-g and 14a-e), respectively. The C₂ symmetry of the complexes in the solid state is demonstrated by X-ray structure investigations performed on 10a, 10f and 15a. Surprisingly high enantioselectivities in the asymmetric hydrogenation of itaconic acid (94% ee) and a-acetamidocinnamic acid (89% ee) are observed on using the Rh complex 9g bearing two monodentate phosphoramidite ligands. Although the chelating bis(phospholanes) described herein are more effective, the adjustable synthesis of the monodentate phosphoramidites may permit the optimization of asymmetric catalytic reactions. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.

Full text of DOI:10.1002/1099-0682(200210)2002:10<2614::AID-EJIC2614>3.0.CO;2-2

FULL PAPER
Chiral Mono- and Bidentate Ligands Derived from -Mannitol and Their
D
Application in Rhodium( )-Catalyzed Asymmetric Hydrogenation Reactions
I
Alexander Bayer,[a] Petra Murszat,[a] Ulf Thewalt,[b] and Bernhard Rieger*[a]
Keywords: Chiral pool / P ligands / Rhodium / Asymmetric catalysis / Hydrogenation
The new monodentate phosphoramidites 8a−g and bidentate
phospholanes 13a−e are prepared in an ex-chiral-pool syn-
prisingly high enantioselectivities in the asymmetric hydro-
genation of itaconic acid (94% ee) and α-acetamidocinnamic
thesis from
ophilic ring opening of bis(epoxides) 6a−b, are the key inter-
mediates for the production of both classes of ligands. Treat- chelating bis(phospholanes) described herein are more ef-
ment of 8a−g or 13a−e with [PdCl2(COD)] or [Rh(COD)2][- fective, the adjustable synthesis of the monodentate phos-
SO3CF3] yield the corresponding Pd (10a, 10f, 15a) and Rh phoramidites may permit the optimization of asymmetric
D
-mannitol. Chiral diols 7a−g, obtained via nucle- acid (89% ee) are observed on using the Rh complex 9g bear-
ing two monodentate phosphoramidite ligands. Although the
compounds (9a−g and 14a−e), respectively. The C2 symmetry
of the complexes in the solid state is demonstrated by X-ray
structure investigations performed on 10a, 10f and 15a. Sur-
catalytic reactions.
( Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany,
2002)
Introduction
(92% ee) when using an asymmetric monophosphonite
compared with the corresponding C2-symmetric diphos-
phonite in the hydrogenation of methyl 2-(acetamido)acryl-
ate.[9] Excellent enantioselectivities (Ͼ 99% ee) are also re-
ported with monodentate phosphites[10] and phosphorami-
dites.[11] These new monodentate ligands have an enantiom-
erically pure binaphthol fragment in common. Based on the
X-ray data of a platinum() complex, Pringle showed that
the cis coordination of two sterically demanding monopho-
sphonite ligands favors one stable conformation at the
metal center, so that rotation about the MϪP bond is pre-
vented. Quadrant diagrams demonstrate the edge-on con-
formation of the bulky binaphthol moiety, presumably
causing the asymmetric induction.[9]
Our approach to achieve high enantioselectivities in
asymmetric hydrogenation reactions is not based on a single
chiral auxiliary group. We present a highly variable ex-
chiral-pool synthesis in order to generate monodentate
phosphoramidites bearing four stereogenic centers, differing
in the absolute configuration of carbon atoms and the steric
demand of the substituents. This synthetic protocol also of-
fers access to functionalized bidentate DuPHOS derivatives.
Both types of ligands were tested in the rhodium()-cata-
lyzed hydrogenation reaction of itaconic and α-(acetamido)-
cinammic acid. The hydrogenation results can be explained
with the help of quadrant diagrams based on X-ray data of
corresponding palladium() complexes.
The enantioselective hydrogenation of prochiral olefins
plays an important role in the application of homogeneous
catalysts. The development of suitable ligands for rhodi-
um() species started in 1968 with Wilkinson-type com-
plexes.[1,2] They used chiral monophosphane ligands, e.g.
methyl(phenyl)(n-propyl)phosphane, which led to poor en-
antioselectivities in rhodium()-catalyzed hydrogenation re-
actions (3Ϫ15% ee). Also, other monodentate ligands failed
to produce high enantioselectivities, while cyclohexyl(o-ani-
syl)methylphosphane (CAMP) was one of the rare excep-
tions (90% ee for hydrogenation of dehydroamino acids).[3]
With the introduction of Kagan’s DIOP, the first chiral di-
phosphane,[4] the research focussed on bidentate ligands.
Knowles et al. showed that DIPAMP, another chelating di-
phosphane, is superior to PAMP, the corresponding mon-
odentate species, with respect to rhodium-catalyzed hydro-
genation reactions.[5] The use of bidentate ligands such as
BINAP[6] and DuPHOS,[7] have also led to extremely high
enantiomeric excess values. These chelating compounds are
supposed to be superior because of the resulting rigid cata-
lysts which favor effective chiral induction.[8] Monodentate
ligands have been neglected in asymmetric hydrogenation
reactions until Pringle et al. questioned the superiority of
the bidentate species. They found higher enantioselectivities
[a]
Department of Inorganic Chemistry II, Materials and Catalysis,
University of Ulm
Albert-Einstein-Allee 11, 89069 Ulm, Germany
Fax: (internat.) ϩ 49-(0)731/502-3039
E-mail: bernhard.rieger@chemie.uni-ulm.de
Ligand and Complex Synthesis
Our approach starts with the chiral building block -
mannitol[12] (1, Figure 1), which is converted into the
[b]
Section for X-ray and Electron Diffraction, University of Ulm
Albert-Einstein-Allee 11, 89069 Ulm, Germany
2614
 WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002 1434Ϫ1948/02/1010Ϫ2614 $ 20.00ϩ.50/0 Eur. J. Inorg. Chem. 2002, 2614Ϫ2624

Chiral Mono- and Bidentate Ligands Derived from -Mannitol
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 (7a); e) CuBr·SMe2, RMgBr, THF/Et2O, Ϫ40 °C, R ϭ CH3 (7b), C2H5 (7c), iC4H9 (7d), C6H5 (7e); f) HMTAP, toluene,
reflux; g) [Rh(COD)2][SO3CF3], CH2Cl2, 9aϪe: M ϭ Rh, L1ϪL2 ϭ COD; h) [PdCl2(COD)], CH2Cl2, 10a: M ϭ Pd, L1 ϭ L2 ϭ Cl
1,2;3,4;5,6-tri-O-isopropylidene (2) and the 3,4-O-isopropy-
The highly variable synthetic strategy allows for the
lidene derivative (3).[13,14] The syntheses of 1,2;5,6-dianhy- conversion of compound 3 (Figure 1) to the diastereomeric
dro-3,4-O-isopropylidene--mannitol (6a),[15] the corres- bis(epoxide) 1,2;5,6-dianhydro-3,4-O-isopropylidene--iditol
ponding chiral diols 7aϪe,[16,17] the monodentate phos- (6b, Figure 2), with a changed configuration at carbon
phoramidites 8aϪe, the Rh complexes 9aϪe and the Pd atoms C2 and C5 (dibenzoylation of 3, ditosylation of 4,
complex 10a were recently reported by us.[18]
subsequent transesterification with concomitant intramole-
Figure 2. i) benzoyl chloride, pyridine, CH2Cl2, Ϫ80 °C; j) tosyl chloride, NEt3, 4-(dimethylamino)pyridine, CH2Cl2; k) K2CO3, MeOH;
l) LiAlH4, Et2O, R ϭ H (7f); m) CuBr·SMe2, PhMgBr, THF/Et2O, Ϫ40 °C, R ϭ C6H5 (7g); n) HMTAP, toluene, reflux; o) [Rh(COD)2][-
SO3CF3], CH2Cl2, 9fϪg: M ϭ Rh, L1ϪL2 ϭ COD; p) [PdCl2(COD)], CH2Cl2, 10f: M ϭ Pd, L1 ϭ L2 ϭ Cl
Eur. J. Inorg. Chem. 2002, 2614Ϫ2624
2615

A. Bayer, P. Murszat, U. Thewalt, B. Rieger
FULL PAPER
cular SN2 reaction of 5).[13] Nucleophilic attack of LiAlH4 orange Rh complexes 14aϪe and the pale yellow Pd analog
opens the epoxide rings of 6b to form (2S,3R,4R,5S)-3,4- 15a by stirring 1 equiv. of 13aϪe with [Rh(COD)2][SO3CF3]
O-isopropylidene-2,3,4,5-hexanetetraol (7f) in a clean reac- or [PdCl2(COD)] in tetrahydrofuran or dichloromethane,
tion.[16,19] Larger substituents [e.g. (2S,3R,4R,5S)-3,4-O- respectively.
isopropylidene-1,6-diphenyl-2,3,4,5-hexanetetraol, 7g, R ϭ
phenyl] can be introduced by nucleophilic ring-opening of
6b with organocuprate reagents generated from the cop-
per() bromideϪdimethylsulfide complex and suitable Grig-
Structure of PdCl2 Complexes
We were not able to grow suitable crystals of the rhodium
nard reagents in diethyl ether.[17,20] Subsequently, the mon- complexes for X-ray analysis, but we succeeded in crystalliz-
odentate phosphoramidites 8fϪg were synthesized in high ing the isoelectronic PdCl2 species 10a, 10f (from methanol)
yields by refluxing 7fϪg and hexamethyltriaminophos- and 15a (from acetone/ethyl acetate). The crystallographic
phane (HMTAP) in toluene. The corresponding orange Rh data of 10a (Figure 4) were already reported on in our latest
complexes 9fϪg and the pale yellow Pd compound 10f were report.[18] The X-ray structure of 10a (C2, C11, C5, C14:
prepared by stirring 2 equiv. of monodentate ligand 9fϪg R; C3, C12, C4, C13: S; ‘‘RSSR’’) indicates the cis coor-
with [Rh(COD)2][SO3CF3] or [PdCl2(COD)] in dichlorome- dination of the two monodentate ligands 8a, and the ex-
thane.
pected square-planar coordination environment of PdII [see
Access to functionalized DuPHOS ligands was offered by (a) in Figure 4, front-view] with a chiral, C2-symmetric ar-
branching off from the key intermediates 7aϪe (Figure 3), rangement of both ligands [see (b) in Figure 4, side-view].
which were readily converted into the corresponding cyclic Furthermore, Figure 4 (b) clearly shows that the tunable
sulfates 11aϪe by reaction with thionyl chloride, followed substituents (Figure 1, CH2ϪR) of the monodentate phos-
by in situ oxidation of the intermediate cyclic sulfite with phoramidites (Figure 4; C1, C10: R ϭ H) occupy the top-
catalytic amounts of RuO4.[21,22] The 1,2-bis(phospholano)- left and bottom-right quadrants [see (c) in Figure 4],
benzenes 12aϪe were prepared by successive treatment of thereby defining a chiral cage around the metal center. The
1,2-bis(phosphanyl)benzene with 2 equiv. of nBuLi, fol- size of the cage is influenced by the nucleophile (R) used
lowed by the addition of 2 equiv. of the corresponding cyc- for the epoxide ring opening.
lic sulfate 11aϪe and an additional 2.2 equiv. of nBuLi.[8]
The diastereomeric PdCl2 complex 10f (C2ϪC5,
The chiral bis(phospholanes) 13aϪe bearing four free hy- C11ϪC14: S; ‘‘SSSS’’) also bears two cis-coordinated mon-
droxy groups were synthesized by cleavage of the protecting odentate phosphoramidites 8f. The C2 symmetry and the
groups (refluxing 12aϪe with methanesulfonic acid in square-planar geometry around the PdII center was deter-
water/methanol).[23Ϫ25] The resulting chiral bis(phosphol- mined by an X-ray structure investigation (Figure 5). The
anes) 13aϪe were converted into the corresponding yellow- corresponding crystallographic data are listed in Table 1
Figure 3. q) (i) SOCl2, NEt3, CH2Cl2; (ii) NaIO4/RuCl3, CH2Cl2/MeCN/H2O; r) (i) 1,2-bis(phosphanyl)benzene, nBuLi, THF; (ii) nBuLi,
THF; s) CH3SO3H, MeOH/H2O, reflux; t) [Rh(COD)2][SO3CF3], THF, 14aϪe: M ϭ Rh, L1ϪL2 ϭ COD; u) [PdCl2(COD)], CH2Cl2,
15a: M ϭ Pd, L1 ϭ L2 ϭ Cl
2616
Eur. J. Inorg. Chem. 2002, 2614Ϫ2624

Chiral Mono- and Bidentate Ligands Derived from -Mannitol
FULL PAPER
Figure 4. Molecular structure of 10a (RSSR); (a) front-view:
square-planar environment of PdII; (b) side-view: C2-symmetric ar-
rangement; hydrogen atoms have been omitted for clarity; (c) quad-
rant diagram
Figure 5. Molecular structure of 10f (SSSS); (a) front-view: square-
planar environment of PdII; (b) side-view: C2-symmetric arrange-
ment; hydrogen atoms have been omitted for clarity; (c) quadrant
diagram
and 3. The side-view shows that the tunable substituents
(Figure 2, CH2ϪR) of the monodentate ligands (Figure 5;
C1, C10: R ϭ H) now occupy the top-right and bottom-left
quadrants less effectively than in 10a [see (c) in Figure 5].
free hydroxy groups (O2, O4) in the axial positions of the
five-membered rings [Figure 6 (c); Table 2 and 3].
In contrast to 10a and 10f, which bear two monodentate Results in the Asymmetric Hydrogenation
ligands each, the PdII complex 15a (C2ϪC5, C8ϪC11: S;
‘‘SSSS’’) consists of a chelating bis(phospholane) (13a).
Reactions
Figure 6 (a) shows the five-membered phospholane rings
The synthesized RhI complexes bearing two monodentate
and the planarity of the 1,2-phenylene moiety. The top view phosphoramidite ligands (9aϪg) or a chelating bis(phos-
in Figure 6 (b) verifies the almost perpendicular orientation pholan)e (14aϪe) were tested in the asymmetric hydrogena-
of the substituents (C1, C6, C7, C12 ϭ CH3) in the equator- tion reactions of α-(acetamido)cinnamic acid (16) and ita-
ial positions of the phospholane ring relative to the square- conic acid (18). Complexes 9aϪe [‘‘RSSR’’, see (A) in Fig-
planar PdII environment. The effective occupation of the ure 7] produce a small excess of N-acetyl-(R)-phenylalanine
top-right and bottom-left quadrants is especially due to the in the hydrogenation of 16 (Table 4, Entries 1Ϫ5), ranging
Eur. J. Inorg. Chem. 2002, 2614Ϫ2624
2617

A. Bayer, P. Murszat, U. Thewalt, B. Rieger
FULL PAPER
˚
Table 1. Selected bond lengths [A] and angles [°] in 10f
Bond lengths
PdϪCl1
PdϪCl2
PdϪP1
PdϪP2
P1ϪO1
P1ϪO2
P1ϪN1
N1ϪC19
2.3581(11)
2.3518(10)
2.2412(8)
2.2324(10)
1.585(2)
1.599(2)
1.631(3)
1.471(6)
1.441(5)
1.461(4)
1.475(4)
C1ϪC2
C2ϪC3
C3ϪC4
C4ϪC5
C5ϪC6
C7ϪC8
C8ϪC9
O3ϪC3
O3ϪC8
O4ϪC4
O4ϪC8
1.501(6)
1.499(5)
1.506(5)
1.534(5)
1.510(6)
1.512(6)
1.498(7)
1.420(4)
1.441(5)
1.426(5)
1.430(5)
N1ϪC20
O1ϪC5
O2ϪC2
Bond angles
Cl1ϪPdϪCl2
P1ϪPdϪCl1
P1ϪPdϪP2
P2ϪPdϪCl2
P1ϪPdϪCl2
P2ϪPdϪCl1
PdϪP1ϪO1
PdϪP1ϪO2
PdϪP1ϪN1
O1ϪP1ϪO2
O1ϪP1ϪN1
O2ϪP1ϪN1
P1ϪN1ϪC19
P1ϪN1ϪC20
C19ϪN1ϪC20
P1ϪO1ϪC5
P1ϪO2ϪC2
C1ϪC2ϪO2
C3ϪC2ϪO2
90.20(5)
88.57(4)
90.77(4)
90.53(5)
177.57(3)
177.82(4)
113.13(10)
115.58(9)
113.88(12)
103.14(13)
106.15(15)
103.80(15)
121.3(3)
123.4(3)
114.6(3)
124.4(2)
123.2(2)
105.8(3)
106.8(3)
C1ϪC2ϪC3
C2ϪC3ϪC4
C2ϪC3ϪO3
C3ϪO3ϪC8
O3ϪC3ϪC4
O3ϪC8ϪC7
O3ϪC8ϪC9
O3ϪC8ϪO4
C7ϪC8ϪC9
C7ϪC8ϪO4
C9ϪC8ϪO4
C8ϪO4ϪC4
O4ϪC4ϪC5
O4ϪC4ϪC3
C3ϪC4ϪC5
C4ϪC5ϪC6
C4ϪC5ϪO1
O1ϪC5ϪC6
116.5(3)
115.8(3)
113.4(3)
106.4(3)
102.2(3)
107.8(4)
110.4(4)
106.1(3)
113.8(4)
111.1(4)
107.4(4)
106.4(3)
114.3(3)
100.1(3)
116.8(3)
113.8(4)
110.9(3)
106.1(4)
from 3 to 36% ee. The highest value in this series (36% ee) is
achieved with 9e which bears the sterically most demanding
benzyl substituent. The absolute configuration (R) of our
hydrogenation products is in accordance with the prediction
of Knowles[26] that the reaction to form (R)-amino acids is
favored if the top-right quadrant of the catalyst’s chiral cage
is not occupied [Figure 4 (c)]. On the other hand, the dia-
stereomeric RhI complexes 9fϪg [‘‘SSSS’’, Figure 7 (B)],
Figure 6. Molecular structure of 15a (SSSS); (a) front-view:
square-planar environment of PdII; (b) top-view: C2-symmetric ar-
rangement; hydrogen atoms have been omitted for clarity; (c) quad-
rant diagram
with the opposite quadrant geometry [cf. PdII complex 10f, 9g, and induces high enantioselectivities due to the ‘‘front
Figure 5 (c)], deliver an excess of the (S) form of N-acetyl- orientation’’ of the phenyl fragments. In contrast, the small
phenylalanine (17) (Entries 6Ϫ7). Complex 9g remarkably methyl substituents in 9f lead to an ‘‘open chiral cage’’ of
yields an 89% ee (S) due to the benzyl groups, whereas the low enantioselectivity.
methyl-substituted analog 9f only gives a 14% ee (S).
Itaconic acid (18), our second test olefin, gave the (S)-
The methyl substituents in 9a [Figure 7 (a), RSSR, C1, configured product after hydrogenation with 9aϪe
C10] occupy the ‘‘front-side’’ of the catalyst, whereas the (‘‘RSSR’’). The % ee values are higher with increasing steric
same groups in 9f [Figure 7 (B), SSSS, C1, C10] are ori- demand of the substituents at the stereogenic centers C2
ented ‘‘sidewards’’. This leads to overall low enantioselec- and C11 (Table 5, Entries 1Ϫ5). Therefore, 9e gives the best
tivities in the case of the methyl derivatives 9a, 9f (R ϭ H), result (61% ee) in this series; 9f also produces a small excess
but with a trend to better results for 9a. This situation (10% ee) of (S)-methylsuccinic acid (19); 9g follows the op-
changes completely for the benzyl-substituted species 9e posite quadrant geometry relative to the former diastereom-
[Figure 7 (A)] and 9g [Figure 7 (B)]. Computer models sug- eric complexes, yielding 19 in an outstanding 94% ee (R)
gest that the sterically demanding benzyl groups (R ϭ Ph) (Entries 6Ϫ7). This indicates that the steric arguments used
in 9e are most probably oriented away from the P1ϪPdϪP2 above (Figure 7) also hold true for other substrates.
plane, pointing into the ‘‘free-areas’’ above and below the
The RhI complexes 14aϪe bearing bidentate ligands once
coordination plane [Figure 7 (A)]. The changed stereochem- again demonstrate their outstanding ability to induce excel-
istry of C2 and C11 (both S) in 9g provides a ‘‘tight chiral lent enantioselectivities in asymmetric hydrogenation reac-
cage’’ in the case of the demanding benzyl substituents in tions. Compounds 14aϪe, with a quadrant diagram ident-
2618
Eur. J. Inorg. Chem. 2002, 2614Ϫ2624

Chiral Mono- and Bidentate Ligands Derived from -Mannitol
FULL PAPER
˚
Table 2. Selected bond lengths [A] and angles [°] in 15a
Bond lengths
PdϪCl1
PdϪP1
P1ϪC2
P1ϪC5
P1ϪC13
C1ϪC2
C2ϪC3
C3ϪO1
2.3786(7)
2.2301(7)
1.852(3)
1.856(4)
1.815(3)
1.525(5)
1.542(4)
1.421(4)
C3ϪC4
C4ϪO2
C4ϪC5
C5ϪC6
C13ϪC14
C13ϪC18
C17ϪC18
C16ϪC17
1.535(5)
1.417(4)
1.555(5)
1.528(5)
1.386(7)
1.399(5)
1.375(6)
1.371(10)
Bond angles
Cl1ϪPdϪCl2
P1ϪPdϪCl1
P1ϪPdϪP2
94.85(3)
88.66(2)
87.95(4)
175.73(3)
113.95(10)
121.13(11)
107.90(11)
114.9(2)
105.2(2)
117.4(2)
105.9(2)
118.11(10)
121.7(3)
120.2(2)
C13ϪC18ϪC17
C18ϪC17ϪC16
C1ϪC2ϪC3
C2ϪC3ϪC4
C2ϪC3ϪO1
O1ϪC3ϪC4
C3ϪC4ϪC5
C3ϪC4ϪO2
O2ϪC4ϪC5
C4ϪC5ϪC6
C2ϪP1ϪC5
C2ϪP1ϪC13
C5ϪP1ϪC13
118.6(4)
121.2(3)
116.1(3)
108.5(2)
112.5(3)
107.8(3)
106.6(3)
111.6(3)
113.9(3)
114.8(3)
95.09(15)
110.33(14)
107.73(15)
P1ϪPdϪCl2
PdϪP1ϪC2
PdϪP1ϪC5
PdϪP1ϪC13
P1ϪC2ϪC1
P1ϪC2ϪC3
P1ϪC5ϪC6
P1ϪC5ϪC4
P1ϪC13ϪC14
P1ϪC13ϪC18
C14ϪC13ϪC18
Figure 7. A) Section of Figure 4 (b); ‘‘RSSR’’ stereochemistry: aryl
substituents occupy top-left and bottom-right quadrant ‘‘face-on’’;
B) section of Figure 5 (b); ‘‘SSSS’’ stereochemistry: ‘‘edge-on’’ ori-
entation of aryl substituents in top-right and bottom-left quadrant,
defining an effective chiral cage; the given % ee values of asymmet-
ric hydrogenation reactions using 9a,e,f,g are related to N-acetyl-
phenylalanine (17)
Table 3. Crystal data and refinement details for 15a and 10f
15a
10f
Formula
Mr
C18H28Cl2O4P2Pd
547.64
trigonal
P3121
C22H44Cl2N2O8P2Pd
703.83
orthorhombic
P212121
293
13.969(3)
14.464(3)
15.756(4)
3183.5(12)
4
Crystal system
Space group
T [K]
203
Table 4. Asymmetric hydrogenation of α-(acetamido)cinnamic acid
(16); the reactions were carried out at room temp. under 1.3 bar of
H2 for 20 h in 5 mL of MeOH with a substrate/[Rh] (10 µmol)
ratio of 244; all reactions achieved 100% conversion; the absolute
configurations and % ee values were determined by chiral HPLC
using Daicel chiral column Chiralpak WH 10 µm (250 mm ϫ 4.6)
with a Waters HPLC 2690 with UV/Vis detection (λ ϭ 254 nm)
˚
a [A]
10.554(1)
10.554(1)
17.876(2)
1724.3(2)
3
1.582
1.20
˚
b [A]
˚
c [A]
3
˚
V [A ]
Z
Dcalcd. [g cmϪ3
]
1.469
0.89
µ [mmϪ1
]
Crystal size [mm]
θ range [°]
Measured reflections 13451
Unique reflections
Rint
Reflections with
I Ͼ 2σ(I)
0.30 ϫ 0.18 ϫ 0.12 0.50 ϫ 0.50 ϫ 0.30
2.23-25.85
2.82Ϫ25.98
33823
6165
2218
0.048
2049
0.060
5008
Goodness-of-fit
R1[F, I Ͼ 2σ(I)]
R1(F, all data)
wR2(F2, all data)
Min./Max. in
0.949
0.020
0.023
0.047
0.993
0.029
0.041
0.067
Entry
Catalyst
ee (%)
1
2
3
4
5
6
7
8
9
9a
9b
18 (R)
3 (R)
5 (R)
Ϫ0.33/0.33
Ϫ0.23/0.39
9c
Ϫ3
˚
∆F [e A
]
9d
10 (R)
36 (R)
14 (S)
89 (S)
99 (S)
98 (S)
98 (S)
97 (S)
96 (S)
Absolute struct.
parameter
Ϫ0.01(3)
Ϫ0.02(2)
9e
9f
9g
14a
14b
14c
14d
14e
ical to 10f, also produce the (S) form of 17 in excellent
enantioselectivities (up to 99% ee for N-acetylphenylalan-
ine). This is clearly a consequence of the enhanced rigidity
of the phenylene backbone (Table 4, Entries 8Ϫ12). The %
10
11
12
Eur. J. Inorg. Chem. 2002, 2614Ϫ2624
2619

A. Bayer, P. Murszat, U. Thewalt, B. Rieger
FULL PAPER
responding metal complexes for given prochiral substrates.
A suitable design strategy can be based on relatively simple
steric considerations, e.g. the ‘‘quadrant model’’ of Knowles
et al. Our results were in accordance with the carefully
drawn structure-selectivity relations based on such quad-
rant diagrams derived from X-ray structures of the corres-
ponding PdII species.
Table 5. Asymmetric hydrogenation of itaconic acid (18); the reac-
tions were carried out at room temp. under 1.3 bar of H2 for 20 h
in 5 mL of MeOH with a substrate/[Rh] (10 µmol) ratio of 192; all
reactions achieved 100% conversion; the absolute configurations
and % ee values were determined by chiral HPLC using Daicel
chiral column Chiralcel OD 10 µm (250 mm ϫ 4.6) with a Waters
HPLC 2690 with UV/Vis detection (λ ϭ 220 nm)
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. Dry methanol (secco solv) was purchased from
Merck. Melting points were determined using a Büchi Melting
Point B-540 apparatus and are uncorrected. Optical rotations were
obtained using a POLAR monitor from IBZ Messtechnik. Ele-
mental analyses were carried out using an Elementar Vario EL.
Mass spectrometry was performed using a Finnigan MAT, TSQ
7000 (FAB; matrix: 2-nitrophenyl octyl ether) and a Finnigan
Entry
Catalyst
ee (%)
1
2
3
4
5
6
7
8
9
9a
9b
18 (S)
27 (S)
27 (S)
44 (S)
61 (S)
10 (S)
94 (R)
Ͼ 99 (R)
Ͼ 99 (R)
98 (R)
99 (R)
98 (R)
9c
9d
9e
9f
9g
14a
14b
14c
14d
14e
10
11
12
1
MAT, SSQ 7000 (CI: CH4; EI: 70 eV). H, 13C, 31P NMR spectra
were recorded with a 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. Enantiomeric excess (% ee) values were measured using
Daicel chiral HPLC columns Chiralcel OD and Chiralpak WH 10
ee values obtained with the hydroxy-substituted bis(phos-
pholanes) 13aϪe are as high as that for the DuPHOS case,
but we did not find a maximal enantioselectivity for the n- µ m (250 mm ϫ 4.6) with a Waters HPLC 2690 with a Knauer
propyl derivative.[8] An increase in the steric demand of our
variable UV/Vis detector. Hydrogen (5.0) was purchased from mti.
All compounds shown in Figure 1 were reported in our latest re-
tunable ligands 13aϪe lowers the resulting enantiomeric ex-
cess of the amino acids produced. Figure 6 (b) shows that
port.[18]
mainly the free hydroxy groups in the axial positions claim
the top-right and bottom-left quadrant. Raising the steric
demand of the equatorial substituents cannot improve the
occupation of the crucial areas.
The (R) form of methylsuccinic acid (19) is produced
throughout with very high enantiomeric excess values (up
to Ͼ 99% ee) (Table 5, Entries 8Ϫ12). The best enantiose-
lectivities are again produced with the catalysts 14a,b with
the smallest substituents in the 2,5-positions of the phos-
pholane moiety.
Synthesis of Chiral Diols 7fϪg
(2S,3R,4R,5S)-3,4-O-Isopropylidene-2,3,4,5-hexanetetraol (7f):
A
solution of 6b (8.85 g, 47.5 mmol) in 50 mL of diethyl ether was
slowly added to a stirred suspension of LiAlH4 (3.61 g, 95.1 mmol)
in 130 mL of diethyl ether. After refluxing for 3 h, the reaction
mixture was carefully hydrolyzed at 0 °C, subsequently with water
and diluted sulfuric acid until the white precipitate dissolved. Ex-
traction with diethyl ether, washing the organic layer with
NaHCO3, drying with Na2SO4 and evaporation of the solvent
25
yielded 7f as a colorless oil. Yield: 5.60 g, 62.0%. [α]D ϭ ϩ26.1
(c ϭ 0.44, CHCl3). 1H NMR (400 MHz, CDCl3): δ ϭ 1.21 (d, 6
H, CH3), 1.40 (s, 6 H, CH3), 3.68Ϫ3.75 (m, 2 H, CH), 3.76Ϫ3.78
(m, 2 H, CH) ppm. 13C NMR: δ ϭ 20.1, 27.4, 67.1, 81.4, 109.4
ppm. MS (CI): m/z ϭ 335 [MHϩ] (ϩMSTFA). C9H18O4 (190.24):
calcd. C 56.82, H 9.54; found C 54.43, H 9.31.
Conclusion
Recently developed chiral monodentate P-ligands based
on binaphthol as the chiral building block show remarkable
(2S,3R,4R,5S)-3,4-O-Isopropylidene-1,6-diphenyl-2,3,4,5-hexa-
selectivities in asymmetric hydrogenation reactions. Here, netetraol (7g): CuBr·SMe2 (0.62 g, 3 mmol) was added to a stirred
suspension of phenylmagnesium bromide (120 mmol) in 100 mL of
diethyl ether at Ϫ40 °C. After stirring at Ϫ40 °C for 2 h, a solution
of 6b (5.59 g, 30 mmol) in 30 mL of tetrahydrofuran was added.
After 1 h of stirring at room temp., the mixture was poured into a
saturated NH4Cl solution. The organic layer was extracted, washed
with water, dried with Na2SO4 and the solvents were evaporated to
we presented an efficient ex-chiral-pool synthesis starting
from -mannitol, which allows for the tailoring of monod-
entate phosphoramidites and bidentate phospholanes. The
diastereoisomers of these new monodenate ligands allow
the exact positioning of substituents with a defined steric
demand at the stereogenic centers. The benzyl-substituted
RhI complex 9g (up to 94% ee) proved that monodentate
ligands can be designed for high enantioselectivities in
asymmetric catalytic reactions of different substrates. This
dryness to give 7g, after flash chromatography (eluting with hex-
21
ane/EtOAc, 7:3), as a colorless oil. Yield: 7.82 g, 76.1%. [α]D
ϭ
1
ϩ10.2 (c ϭ 0.53, CHCl3). H NMR (400 MHz, CDCl3): δ ϭ 1.43
(s, 6 H, CH3), 2.70Ϫ2.83 (m, 4 H, CH2), 3.66Ϫ3.71 (m, 2 H, CH),
opens the possibility to fine-tune our ligands and the cor- 3.95Ϫ3.99 (m, 2 H, CH), 7.13Ϫ7.26 (m, 10 H, CHarom.) ppm. 13C
2620
Eur. J. Inorg. Chem. 2002, 2614Ϫ2624

Chiral Mono- and Bidentate Ligands Derived from -Mannitol
FULL PAPER
NMR: δ ϭ 27.1, 41.1, 70.9, 78.6, 109.3, 126.4, 128.4, 129.2, 137.9 {Bis[(4S,5S,6S,7S)-5,6-O-isopropylidene-2-(dimethylamino)-4,7-
ppm. MS (CI): m/z ϭ 343 [MHϩ]. C21H26O4 (342.4): calcd. C dimethyl-1,3,2-dioxaphosphepane]}PdCl2 (10f): A solution of 2
73.66, H 7.65; found C 72.44, H 7.62.
equiv. of the monodentate ligand 8f in 50 mL of dichloromethane
was added to stirred solution of [PdCl2(COD)] (500 mg,
a
General Procedure for the Synthesis of 8fϪg: Chiral diols 7fϪg
(6.2 mmol) and NH4Cl (10 mg) were refluxed in 150 mL of toluene.
HMTAP (1.24 mL, 6.8 mmol) was added to this refluxing solution
and stirred for a further 8 h. The mixture was concentrated under
reduced pressure affording colorless oils.
1.75 mmol) in 70 mL of dichloromethane at 0 °C. After stirring at
room temp. for 2 h, the solvent was removed under reduced pres-
sure. Washing of the residue twice with 50 mL of diethyl ether and
drying in vacuo resulted in a pale yellow powder. Yield: 1.13 g,
91.7%. 1H NMR (400 MHz, CDCl3): δ ϭ 1.34 (d, 6 H, CH3), 1.37
(s, 12 H, CH3), 1.38 (d, 6 H, CH3), 2.86Ϫ2.89 (m, 12 H, NϪCH3),
4.34Ϫ4.44 (m, 4 H, CH), 4.73Ϫ4.81 (m, 2 H, CH), 5.20Ϫ5.28 (m,
2 H, CH) ppm. 13C NMR: δ ϭ 15.4, 16.7, 26.7, 26.9, 38.1, 72.9,
74.4, 75.4, 75.9, 111.8 ppm. 31P NMR: δ ϭ 101.47 (s) ppm. MS
(FAB): m/z ϭ 669 [(M Ϫ ClϪ)ϩ]. C22H44N2O8P2PdCl2 (703.9):
calcd. C 37.54, H 6.30, N 3.98; found C 35.66, H 6.45, N 4.18.
(4S,5S,6S,7S)-5,6-O-Isopropylidene-2-(dimethylamino)-4,7-di-
methyl-1,3,2-dioxaphosphepane-5,6-diol (8f): Yield: 1.59 g, 97.3%.
23
1
[α]D ϭ Ϫ67.1 (c ϭ 0.41, CHCl3). H NMR (400 MHz, CDCl3):
δ ϭ 1.24 (d, 3 H, CH3), 1.36 (s, 3 H, CH3), 1.37 (s, 3 H, CH3), 1.42
(d, 3 H, CH3), 2.57 (s, 3 H, NϪCH3), 2.60 (s, 3 H, NϪCH3),
4.24Ϫ4.27 (m, 1 H, CH), 4.41Ϫ4.56 (m, 3 H, CH) ppm. 13C NMR:
δ ϭ 15.0, 16.4, 27.2, 34.8, 35.0, 68.4, 69.8, 75.7, 76.3, 110.3 ppm.
31P NMR: δ ϭ 140.48 (s) ppm. MS (CI): m/z ϭ 264 [MHϩ].
C11H22NO4P (263.3): calcd. C 50.18, H 8.42, N 5.32; found C
48.38, H 8.41, N 6.21.
General Procedure for the Synthesis of the Cyclic Sulfates 11aϪe:
11a,b have already been reported.[24] A solution of thionyl chloride
(1.91 mL, 26 mmol) in 20 mL of dichloromethane was added to a
stirred solution of the corresponding chiral diol 7cϪe (24 mmol)
and pyridine (4.26 mL, 53 mmol) in 100 mL of dichloromethane
at 0 °C. After 3 h at room temp., the reaction mixture was washed
with water and the organic layer extracted, dried with Na2SO4 and
the solvents were evaporated to dryness. The resulting oil was redis-
solved in 40 mL of dichloromethane and 40 mL of acetonitrile, and
NaIO4 (10.25 g, 48 mmol) and RuCl3·nH2O (34 mg) in 60 mL of
water were then added. After 1 h at room temp., the organic layer
was extracted with dichloromethane, washed with brine, dried with
Na2SO4 and the solvents were evaporated to dryness. The products
were isolated by filtration through silica (eluent: dichloromethane).
After concentration to dryness, the cyclic sulfates 11cϪd were ob-
tained as colorless crystals, 11e as a pale yellow oil.
(4S,5S,6S,7S)-5,6-O-Isopropylidene-2-(dimethylamino)-4,7-dibenzyl-
1,3,2-dioxaphosphepane-5,6-diol (8g): Yield: 2.38 g, 92.4%. [α]D21 ϭ
1
Ϫ50.0 (c ϭ 0.01, CHCl3). H NMR (400 MHz, CDCl3): δ ϭ 1.49
(s, 6 H, CH3), 2.45 (s, 3 H, NϪCH3), 2.48 (s, 3 H, NϪCH3),
2.70Ϫ2.78 (m, 1 H, CH2), 3.09Ϫ3.25 (m, 3 H, CH2), 4.43Ϫ4.61
(m, 3 H, CH), 4.73Ϫ4.79 (m, 1 H, CH), 7.17Ϫ7.29 (m, 10 H,
CHarom.) ppm. 13C NMR: δ ϭ 27.0, 27.2, 34.3, 34.8, 35.0, 36.7,
73.3, 74.8, 76.4, 77.3, 110.6, 126.09, 126.13, 128.1, 128.2, 129.6,
129.8, 138.8, 139.1 ppm. 31P NMR: δ ϭ 140.24 (s) ppm. MS (CI):
m/z ϭ 417 [MHϩ]. C23H30NO4P (415.5): calcd. C 66.49, H 7.28, N
3.37; found C 62.56, H 7.07, N 3.56.
(4R,5S,6S,7R)-5,6-O-Isopropylidene-4,7-di-n-propyl-1,3,2-dioxa-
thiepane 2,2-Dioxide (11c): Yield: 5.48 g, 74.2%; m.p. 36Ϫ38 °C.
General Procedure for the Synthesis of Rhodium(i) Complexes 9fϪg:
A solution of 2 equiv. of the corresponding monodentate phos-
phoramidite 8fϪg in 20 mL of 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
temp., the solvent was removed under reduced pressure. The re-
sulting orange solid was washed twice with 50 mL of pentane and
dried in vacuo.
24
[α]D ϭ ϩ45.4 (c ϭ 1.0, CHCl3). 1H NMR (400 MHz, CDCl3):
δ ϭ 0.94 (t, 6 H, CH3), 1.38 (s, 6 H, CH3), 1.41Ϫ1.49 (m, 2 H,
CH2), 1.55Ϫ1.64 (m, 2 H, CH2), 1.81Ϫ1.86 (m, 4 H, CH2),
3.98Ϫ4.04 (m, 2 H, CH), 4.25Ϫ4.31 (m, 2 H, CH) ppm. 13C NMR:
δ ϭ 13.5, 18.0, 26.7, 34.2, 79.6, 84.6, 110.5 ppm. MS (CI): m/z ϭ
309 [MHϩ]. C13H24O6S (308.4): calcd. C 50.63, H 7.84; found C
49.81, H 7.69.
{Bis[(4S,5S,6S,7S)-5,6-O-isopropylidene-2-(dimethylamino)-4,7-
dimethyl-1,3,2-dioxaphosphepane]RhI(COD)} Trifluoromethanesul-
fonate (9f): Yield: 528 mg, 93.0%. 1H NMR (400 MHz, CDCl3):
δ ϭ 1.23 (d, 6 H, CH3), 1.33 (d, 6 H, CH3), 1.38 (s, 12 H, CH3),
2.31Ϫ2.57 (m, 8 H, CH2,COD), 2.97Ϫ3.01 (m, 12 H, NϪCH3),
4.29Ϫ4.35 (m, 2 H, CH), 4.41Ϫ4.46 (m, 2 H, CH), 4.52Ϫ4.64 (m,
4 H, CH), 5.10Ϫ5.17 (m, 2 H, CHCOD), 5.52Ϫ5.59 (m, 2 H,
CHCOD) ppm. 31P NMR: δ ϭ 117.06 (d) ppm. MS (FAB): m/z ϭ
737 [(M Ϫ SO3CF3Ϫ)ϩ]. C31H56F3N2O11P2RhS (886.7): calcd. C
41.99, H 6.37, N 3.16; found C 41.87, H 6.48, N 2.55.
(4R,5S,6S,7R)-4,7-Diisopentyl-5,6-O-isopropylidene-1,3,2-dioxa-
thiepane 2,2-Dioxide (11d): Yield: 7.22 g, 82.6%; m.p. 36Ϫ38 °C.
24
[α]D ϭ ϩ45.3 (c ϭ 1.0, CHCl3). 1H NMR (400 MHz, CDCl3):
δ ϭ 0.88Ϫ0.90 (m, 12 H, CH3), 1.23Ϫ1.34 (m, 2 H, CH2), 1.39 (s,
6 H, CH3), 1.42Ϫ1.50 (m, 2 H, CH2), 1.51Ϫ1.61 (m, 2 H, CH),
1.77Ϫ1.93 (m, 4 H, CH2), 3.99Ϫ4.04 (m, 2 H, CH), 4.22Ϫ4.28 (m,
2 H, CH) ppm. 13C NMR: δ ϭ 22.2, 22.5, 26.8, 27.7, 30.2, 33.6,
79.7, 85.3, 110.6 ppm. MS (CI): m/z ϭ 365 [MHϩ]. C17H32O6S
(364.5): calcd. C 56.02, H 8.85; found C 55.41, H 8.89.
(4R,5S,6S,7R)-4,7-Dibenzyl-5,6-O-isopropylidene-1,3,2-dioxa-
{Bis[(4S,5S,6S,7S)-5,6-O-isopropylidene-2-(dimethylamino)-4,7-
dibenzyl-1,3,2-dioxaphosphepane]RhI(COD)} Trifluoromethanesul-
fonate (9g): Yield: 734 mg, 96.2%. 1H NMR (400 MHz, CDCl3):
δ ϭ 1.37 (s, 6 H, CH3), 1.39 (s, 6 H, CH3), 2.17Ϫ2.54 (m, 8 H,
CH2COD), 2.38Ϫ2.44 (m, 12 H, NϪCH3), 2.60Ϫ2.75 (m, 4 H,
CH2), 2.95Ϫ3.06 (m, 4 H, CH2), 4.10Ϫ4.16 (m, 2 H, CH),
4.26Ϫ4.31 (m, 2 H, CH), 4.45Ϫ4.53 (m, 2 H, CH), 4.53Ϫ4.59 (m, 2
H, CH), 4.78Ϫ4.86 (m, 2 H, CHCOD), 5.45Ϫ5.53 (m, 2 H, CHCOD),
23
thiepane 2,2-Dioxide (11e): Yield: 8.07 g, 83.2%. [α]D ϭ ϩ54.2
1
(c ϭ 1.0, CHCl3). H NMR (400 MHz, CDCl3): δ ϭ 1.44 (s, 6 H,
CH3), 3.07Ϫ3.18 (m, 4 H, CH2), 4.02Ϫ4.07 (m, 2 H, CH),
4.39Ϫ4.45 (m, 2 H, CH), 7.18Ϫ7.28 (m, 10 H, CHarom.) ppm. 13C
NMR: δ ϭ 26.8, 38.1, 78.7, 84.5, 110.9, 127.1, 128.5, 129.6, 135.1
ppm. MS (CI): m/z ϭ 405 [MHϩ]. C21H24O6S (404.49): calcd. C
62.39, H 5.98; found C 59.56, H 5.95.
7.05Ϫ7.32 (m, 20 H, CHarom.) ppm. 31P NMR: δ ϭ 116.60 (d) ppm. General Procedure for the Synthesis of the Bis(phospholanes) 12aϪe:
MS (FAB): m/z ϭ 1041 [(M Ϫ SO3CF3Ϫ)ϩ]. C55H72F3N2O11P2RhS 12a,b have already been reported.[24] A solution of 1.6  n-butylli-
(1191.1): calcd. C 55.46, H 6.09, N 2.35; found C 54.28, H 6.22,
N 2.31.
thium (8.0 mL, 12.8 mmol) in n-hexane was added to a stirred solu-
tion of 1,2-bis(phosphanyl)benzene (0.91 g, 6.4 mmol) in 50 mL of
Eur. J. Inorg. Chem. 2002, 2614Ϫ2624
2621

A. Bayer, P. Murszat, U. Thewalt, B. Rieger
FULL PAPER
tetrahydrofuran. After 2 h at room temp., the corresponding cyclic
sulfate 11cϪe (12.8 mmol) in 50 mL of tetrahydrofuran was added.
After an additional 4 h at room temp., n-butyllithium (8.8 mL of
1.6  solution, 14.1 mmol) in n-hexane was added. After 16 h at
room temp., the excess n-butyllithium was hydrolyzed with 3 mL
of methanol. The reaction solvents were evaporated to dryness. The
resulting yellow oil was extracted twice with 50 mL n-pentane.
After concentrating to dryness, the bidentate ligands were obtained
as a white powder (12dϪe) or a colorless oil (12c).
12 H, CH2), 1.53Ϫ1.66 (m, 2 H, CH2), 1.68Ϫ1.83 (m, 2 H, CH2),
2.53Ϫ2.66 (m, 2 H, CH), 2.82Ϫ2.89 (m, 2 H, CH), 4.14Ϫ4.19 (m,
4 H, CH), 7.18Ϫ7.22 (m, 2 H, CHarom.), 7.89Ϫ7.93 (m, 2 H,
CHarom.) ppm. 13C NMR: δ ϭ 14.9, 15.0, 23.8, 24.4, 30.6, 32.9,
41.7, 45.3, 80.0, 81.0, 129.1, 135.3, 144.8 ppm. 31P NMR: δ ϭ
Ϫ10.36 (s) ppm. MS (CI): m/z ϭ 483 [MHϩ]. C26H44O4P2 (482.5):
calcd. C 64.72, H 9.19; found C 62.77, H 9.00.
1,2-Bis[(2S,3S,4S,5S)-3,4-dihydroxy-2,5-diisopentylphosphol-
anyl]benzene (13d): Yield: 1.13 g, 90.2%; m.p. 150Ϫ155 °C. [α]D24 ϭ
ϩ89.2 (c ϭ 0.25, MeOH). 1H NMR (400 MHz, MeOD): δ ϭ
0.68Ϫ0.81 (m, 24 H, CH3), 0.83Ϫ0.90 (m, 4 H, CH), 1.04Ϫ1.27
(m, 6 H, CH2), 1.31Ϫ1.40 (m, 4 H, CH2), 1.42Ϫ1.52 (m, 2 H, CH2),
1.53Ϫ1.65 (m, 2 H, CH2), 1.77Ϫ1.91 (m, 2 H, CH2), 2.50Ϫ2.63
(m, 2 H, CH), 2.77Ϫ2.87 (m, 2 H, CH), 4.16Ϫ4.20 (m, 4 H, CH),
7.18Ϫ7.22 (m, 2 H, CHarom.), 7.88Ϫ7.92 (m, 2 H, CHarom.) ppm.
31P NMR: δ ϭ Ϫ10.04 (s) ppm. MS (CI): m/z ϭ 595 [Mϩ].
C34H60O4P2 (594.7): calcd. C 68.67, H 10.17; found C 66.22, H
9.89.
1,2-Bis[(2S,3S,4S,5S)-3,4-O-isopropylidene-2,5-diisopropylphos-
24
pholanyl]benzene (12c): Yield: 2.37 g, 65.8%. [α]D ϭ ϩ189.3 (c ϭ
0.783, CHCl3). 1H NMR (400 MHz, CDCl3): δ ϭ 0.57 (t, 6 H,
CH3), 0.69Ϫ0.78 (m, 2 H, CH2), 0.85 (t, 6 H, CH3), 0.95Ϫ1.05 (m,
2 H, CH2), 1.23Ϫ1.35 (m, 6 H, CH2), 1.37Ϫ1.42 (m, 2 H, CH2),
1.44 (s, 6 H, CH3), 1.45 (s, 6 H, CH3), 1.47Ϫ1.56 (m, 2 H, CH2),
1.81Ϫ1.97 (m, 2 H, CH2), 2.24Ϫ2.29 (m, 2 H, CH), 2.61Ϫ2.73 (m,
2 H, CH), 4.33Ϫ4.46 (m, 4 H, CH), 7.30Ϫ7.38 (m, 4 H, CHarom.
)
ppm. 13C NMR: δ ϭ 13.90, 13.91, 21.6, 22.9, 27.2, 27.3, 29.8, 29.9,
30.6, 30.9, 81.3, 82.2, 117.0, 129.2, 131.1, 141.2 ppm. 31P NMR:
δ ϭ 35.95 (s) ppm. MS (CI): m/z ϭ 563 [MHϩ]. C32H52O4P2
(562.7): calcd. C 68.30, H 9.31; found 64.18, H 8.56.
1,2-Bis[(2S,3S,4S,5S)-2,5-dibenzyl-3,4-dihydroxyphosphol-
anyl]benzene (13e): Yield: 0.81 g, 56.9%; m.p. 178Ϫ183 °C. [α]D24 ϭ
ϩ37.9 (c ϭ 0.174, MeOH). 1H NMR (400 MHz, MeOD): δ ϭ
2.05Ϫ2.27 (m, 2 H, CH2), 2.75Ϫ2.85 (m, 2 H, CH2), 2.89Ϫ3.04
(m, 4 H, CH2), 3.06Ϫ3.18 (m, 2 H, CH), 3.31Ϫ3.43 (m, 2 H, CH),
3.83Ϫ3.93 (m, 2 H, CH), 3.99Ϫ4.06 (m, 2 H, CH), 6.80Ϫ7.37 (m,
24 H, CHarom.) ppm. 31P NMR: δ ϭ Ϫ11.13 (s) ppm. MS (CI):
m/z ϭ 675 [Mϩ]. C42H44O4P2 (674.7): calcd. C 74.77, H 6.57; found
C 73.34, H 6.58.
1,2-Bis[(2S,3S,4S,5S)-2,5-diisopentyl-3,4-O-isopropylidenephos-
pholanyl]benzene (12d): Yield: 3.00 g, 69.3%; m.p. 125Ϫ130 °C.
23
1
[α]D ϭ ϩ136.5 (c ϭ 0.31, CHCl3). H NMR (400 MHz, CDCl3):
δ ϭ 0.48 (d, 6 H, CH3), 0.59 (d, 6 H, CH3), 0.72Ϫ0.81 (m, 4 H,
CH), 0.85 (d, 12 H, CH3), 0.85Ϫ0.90 (m, 2 H, CH2), 1.04Ϫ1.13
(m, 4 H, CH2), 1.15Ϫ1.24 (m, 2 H, CH2), 1.26Ϫ1.42 (m, 4 H, CH2),
1.46 (s, 6 H, CH3), 1.47 (s, 6 H, CH3), 1.47Ϫ1.56 (m, 2 H, CH2),
1.87Ϫ2.00 (m, 2 H, CH2), 2.15Ϫ2.20 (m, 2 H, CH), 2.54Ϫ2.66 (m,
General Procedure for the Synthesis of the Rhodium(i) Complexes
14aϪe: A solution of 1 equiv. of the corresponding bis(phosphol-
ane) 13aϪe in 30 mL of tetrahydrofuran was added to a solution
of [Rh(COD)2][SO3CF3] (400 mg, 0.85 mmol) in 50 mL of tetrahy-
drofuran at room temp. After 3 h of stirring at room temp., the
reaction solvents were evaporated to dryness. The orange residue
was washed twice with 50 mL of diethyl ether and dried in vacuo.
2 H, CH), 4.32Ϫ4.49 (m, 4 H, CH), 7.31Ϫ7.37 (m, 4 H, CHarom.
)
ppm. 13C NMR: δ ϭ 22.3, 22.4, 22.6, 22.7, 25.2, 26.1, 27.31, 27.33,
28.2, 28.4, 31.3, 31.4, 38.3, 38.9, 81.3, 82.4, 117.1, 129.2, 131.3,
141.2 ppm. 31P NMR: δ ϭ 36.71 (s) ppm. MS (CI): m/z ϭ 676
[MHϩ]. C40H68O4P2 (674.9): calcd. C 71.18, H 10.15; found C
67.24, H 9.69.
[{1,2-Bis[(2S,3S,4S,5S)-3,4-dihydroxy-2,5-dimethylphosphol-
anyl]benzene}RhI(COD)] Trifluoromethanesulfonate (14a): Yield:
582 mg, 93.3%. H NMR (400 MHz, MeOD): δ ϭ 0.91Ϫ0.96 (m,
6 H, CH3), 1.34Ϫ1.40 (m, 6 H, CH3), 2.17Ϫ2.64 (m, 8 H, CH2COD),
2.79Ϫ2.89 (m, 4 H, CH), 4.06Ϫ4.14 (m, 2 H, CH), 4.16Ϫ4.24 (m, 2
H, CH), 5.54Ϫ5.61 (m, 2 H, CHCOD), 5.95Ϫ6.04 (m, 2 H, CHCOD),
7.55Ϫ7.58 (m, 2 H, CHarom.), 8.62Ϫ8.66 (m, 2 H, CHarom.) ppm.
31P NMR: δ ϭ 78.20 (d) ppm. MS (FAB): m/z ϭ 581 [(M Ϫ
SO3CF3Ϫ)ϩ]. C27H40F3O7P2RhS (730.5): calcd. C 44.39, H 5.52;
found C 43.36, H 5.78.
1,2-Bis[(2S,3S,4S,5S)-2,5-dibenzyl-3,4-O-isopropylidenephosphol-
anyl]benzene (12e): Yield: 2.64 g, 54.6%; m.p. 136Ϫ140 °C. [α]D23 ϭ
ϩ28.1 (c ϭ 0.089, CHCl3). 1H NMR (400 MHz, CDCl3): δ ϭ 1.47
(s, 12 H, CH3), 2.05Ϫ2.10 (m, 2 H, CH2), 2.49Ϫ2.55 (m, 2 H, CH2),
2.67Ϫ2.73 (m, 2 H, CH2), 2.79Ϫ2.88 (m, 2 H, CH2), 3.12Ϫ3.26
(m, 4 H, CH), 4.43Ϫ4.63 (m, 4 H, CH), 6.89Ϫ7.44 (m, 24 H,
CHarom.) ppm. 13C NMR: δ ϭ 27.3, 27.4, 30.9, 32.2, 24.0, 35.1,
81.0, 81.9, 117.8, 125.6, 126.0, 127.8, 128.2, 128.6, 128.9, 129.0,
129.7, 130.8, 141.3, 141.4 ppm. 31P NMR: δ ϭ 42.39 (s) ppm. MS
(CI): m/z ϭ 755 [Mϩ]. C48H52O4P2 (754.9): calcd. C 76.37, H 6.94;
found C 75.04, H 6.65.
1
[{1,2-Bis[(2S,3S,4S,5S)-3,4-dihydroxy-2,4-diethylphospholanyl]-
benzene}RhI(COD)] Trifluoromethanesulfonate (14b): Yield:
General Procedure for the Synthesis of the Bis(phospholanes) 13aϪe:
13a,b have already been reported.[24,25] Methanesulfonic acid (1 mL
of a 70% solution) in water was added to a stirred solution of the
corresponding bis(phospholane) 12cϪe (2.11 mmol) in 50 mL of
methanol at room temp. After 2.5 h of stirring under reflux, the
reaction solvents were evaporated to dryness. The residue was dis-
solved in 30 mL of ethyl acetate and 30 mL of water. K2CO3 was
then added until neutral reaction of litmus. After stirring for several
hours, the organic layer was separated and dried with Na2SO4.
Concentration to dryness yielded bis(phospholanes) 13cϪe as
white solids.
1
615 mg, 91.5%. H NMR (400 MHz, MeOD): δ ϭ 0.85Ϫ0.88 (t, 6
H, CH3), 0.93Ϫ0.96 (t, 6 H, CH3), 1.43Ϫ1.54 (m, 2 H, CH2),
1.81Ϫ1.91 (m, 2 H, CH2), 1.91Ϫ2.04 (m, 2 H, CH2), 2.14Ϫ2.22
(m, 2 H, CH2), 2.29Ϫ2.65 (m, 8 H, CH2COD), 2.57Ϫ2.65 (m, 2 H,
CH), 2.67Ϫ2.75 (m, 2 H, CH), 4.18Ϫ4.34 (m, 4 H, CH), 5.53Ϫ5.58
(m, 2 H, CHCOD), 5.89Ϫ5.95 (m, 2 H, CHCOD), 7.54Ϫ7.57 (m, 2
H, CHarom.), 8.65Ϫ8.69 (m, 2 H, CHarom.). 31P NMR: δ ϭ 71.50
(d) ppm. MS (FAB): m/z
ϭ 637 [(M Ϫ
SO3CF3Ϫ)ϩ].
C31H48F3O7P2RhS (786.6): calcd. C 47.33, H 6.15; found C 46.7,
H 6.13.
1,2-Bis[(2S,3S,4S,5S)-3,4-dihydroxy-2,5-di-n-propylphospholanyl]- [{1,2-Bis[(2S,3S,4S,5S)-3,4-dihydroxy-2,5-di-n-propylphospholanyl]-
benzene}RhI(COD)] Trifluoromethanesulfonate (14c): Yield:
26
benzene (13c): Yield: 0.73 g, 71.9%; m.p. 100Ϫ103 °C. [α]D
ϭ
ϩ103.7 (c ϭ 0.52, MeOH). 1H NMR (400 MHz, MeOD): δ ϭ 679 mg, 94.4%. H NMR (400 MHz, MeOD): δ ϭ 0.74Ϫ0.80 (m,
1
0.69Ϫ0.72 (t, 6 H, CH3), 0.77Ϫ0.82 (t, 6 H, CH3), 1.12Ϫ1.36 (m,
12 H, CH3), 0.82Ϫ1.68 (m, 10 H, CH2), 1.79Ϫ1.98 (m, 4 H, CH2),
Eur. J. Inorg. Chem. 2002, 2614Ϫ2624
2622

Chiral Mono- and Bidentate Ligands Derived from -Mannitol
FULL PAPER
2.13Ϫ2.26 (m, 2 H, CH2), 2.27Ϫ2.67 (m, 8 H, CH2COD), 2.68Ϫ2.76 tem). Graphite-monochromatized Mo-Kα radiation (λ ϭ 0.71073
˚
(m, 2 H, CH), 2.79Ϫ2.88 (m, 2 H, CH), 4.12Ϫ4.33 (m, 4 H, CH), A) was used. Crystal data are listed in Table 3, together with refine-
5.46Ϫ5.57 (m, 2 H, CHCOD), 5.88Ϫ5.99 (m, 2 H, CHCOD),
ment details. The lattice constants correspond to the temperatures
7.55Ϫ7.60 (m, 2 H, CHarom.), 8.65Ϫ8.69 (m, 2 H, CHarom.) ppm. indicated there. Absorption corrections were not applied. The
31P NMR: δ ϭ 71.87 (d) ppm. MS (FAB): m/z ϭ 693 [(M Ϫ
SO3CF3Ϫ)ϩ]. C35H56F3O7P2RhS (842.7): calcd. C 49.89, H 6.70;
found C 50.31, H 6.75.
structures were solved by the Patterson method with the SHELXS-
86 program.[27] The atomic coordinates and anisotropic thermal
parameters of the non-hydrogen atoms were refined using the
SHELXL-97 program;[28] full-matrix method on F2 data. Hydrogen
atoms were included in the final refinement cycles, except those of
atoms C15, C16, C18, C19 and C22 of 10f, since these were highly
anisotropic. The riding model was used for the hydrogen atoms. By
using the absolute structure parameter[29] as a criterion, it could be
decided which of the enantiomers in both cases corresponds to the
crystal investigated, and that in the case of 15a, P3121 is the
correct space group and not P3221. CCDC-177475 and -177476
for 15a and 10f contain the supplementary crystallographic
data for this paper. These data can be obtained free of charge at
www.ccdc.cam.ac.uk/conts/retrieving.html or from the Cambridge
Crystallographic Data Centre, 12, Union Road, Cambridge
[{1,2-Bis[(2S,3S,4S,5S)-3,4-dihydroxy-2,5-diisopentylphos-
pholanyl]benzene}RhI(COD)] Trifluoromethanesulfonate (14d):
Yield: 763 mg, 93.5%. 1H NMR (400 MHz, MeOD):
δ ϭ
0.66Ϫ0.69 (m, 12 H, CH3), 0.78 (d, 6 H, CH3), 0.83 (d, 6 H, CH3),
0.86Ϫ0.95 (m, 4 H, CH), 0.99Ϫ1.66 (m, 12 H, CH2), 1.71Ϫ1.83
(m, 2 H, CH2), 2.00Ϫ2.14 (m, 2 H, CH2), 2.14Ϫ2.65 (m, 8 H,
CH2COD), 2.65Ϫ2.80 (m, 4 H, CH), 4.15Ϫ4.34 (m, 4 H, CH),
5.50Ϫ5.57 (m, 2 H, CHCOD), 5.94Ϫ6.03 (m, 2 H, CHCOD),
7.53Ϫ7.61 (m, 2 H, CHarom.), 8.62Ϫ8.69 (m, 2 H, CHarom.) ppm.
31P NMR: δ ϭ 73.36 (d) ppm. MS (FAB): m/z ϭ 805 [(M Ϫ
SO3CF3Ϫ)ϩ]. C43H72F3O7P2RhS (954.9): calcd. C 54.09, H 7.60;
found C 52.00, H 7.47.
CB2 1EZ, UK [Fax: (internat.)
deposit@ccdc.cam.ac.uk].
ϩ 44-1223/336-033; E-mail:
[{1,2-Bis[(2S,3S,4S,5S)-2,5-dibenzyl-3,4-dihydroxyphos-
pholanyl]benzene}RhI(COD)] Trifluoromethanesulfonate (14e):
Yield: 803 mg, 90.9%. 1H NMR (400 MHz, MeOD):
δ ϭ
2.19Ϫ2.63 (m, 8 H, CH2COD), 2.68Ϫ2.89 (m, 4 H, CH2), 2.91Ϫ2.99
(m, 2 H, CH2), 3.00Ϫ3.08 (m, 2 H, CH2), 3.09Ϫ3.24 (m, 2 H, CH),
3.41Ϫ3.53 (m, 2 H, CH), 3.91Ϫ4.16 (m, 4 H, CH), 5.41Ϫ5.49 (m,
2 H, CHCOD), 6.04Ϫ6.11 (m, 2 H, CHCOD), 6.77Ϫ8.85 (m, 24 H,
CHarom.) ppm. 31P NMR: δ ϭ 72.40 (d) ppm. MS (FAB): m/z ϭ
885 [(M Ϫ SO3CF3Ϫ)ϩ]. C51H56F3O7P2RhS (1034.8): calcd. C
59.19, H 5.45; found C 58.04, H 5.38.
Acknowledgments
We thank the Deutsche Forschungsgemeinschaft for financial sup-
port of this work (Ri613/5-1). A. B. was further supported by a
scholarship of the state of Baden-Württemberg.
{1,2-Bis[(2S,3S,4S,5S)-3,4-dihydroxy-2,5-dimethylphosphol-
anyl]benzene}PdIICl2 (15a): A solution of 12a (2.10 g, 4.66 mmol)
in 50 mL of dichloromethane was added to a solution of
[PdCl2(COD)] (1.10 g, 3.85 mmol) in 50 mL of dichloromethane.
The yellow solution was stirred for 1 h at room temp. and the solv-
ents were evaporated to dryness. The residue was washed twice with
50 mL of n-pentane and dissolved in 50 mL of dichloromethane.
On addition of 20 mL of water, and a small amount of hydrochloric
acid, a pale yellow powder precipitated. After stirring for 1 h at
room temp., the precipitate was filtered off, washed with dichloro-
methane and dried in vacuo. Yield: 1.87 g, 88.6%. 1H NMR
(400 MHz, MeOD): δ ϭ 0.91Ϫ0.99 (m, 6 H, CH3), 1.35Ϫ1.44 (m,
6 H, CH3), 3.09Ϫ3.19 (m, 2 H, CH), 3.51Ϫ3.60 (m, 2 H, CH),
3.97Ϫ4.08 (m, 2 H, CH), 4.15Ϫ4.25 (m, 2 H, CH), 7.73Ϫ7.79 (m,
2 H, CHarom.), 8.49Ϫ8.55 (m, 2 H, CHarom.) ppm. 31P NMR: δ ϭ
[1]
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ϭ 513 [(M Ϫ
ClϪ)ϩ].
[9]
Martorell, A. G. Orpen, P. G. Pringle, Chem. Commun. 2000,
C18H28Cl2O4P2Pd (547.7): calcd. C 39.47, H 5.15; found C 39.47,
H 5.09.
961Ϫ962.
[10]
M. T. Reetz, G. Mehler, Angew. Chem. 2000, 112, 4047Ϫ4049;
General Procedure for the Asymmetric Hydrogenation: Hydrogena-
tion reactions were performed using standard Schlenk techniques.
Methanol Secco Solv was purchased from Merck and stored over
molecular sieves. In a Schlenk tube, the corresponding RhI com-
plex, 9aϪg, 14aϪe, (10 µmol) and 16 (500 mg, 2.44 mmol) or 18
(250 mg, 1.92 mmol) were dissolved in 5 mL of methanol. After
three vacuum/nitrogen cycles, followed by one vacuum/hydrogen
cycle (1.3 bar), the reaction mixture was stirred at room temp. for
20 h. The reaction products were filtered through a short silica col-
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M. Berg, Van den, A. J. Minnaard, E. D. Schudde, J. Esch,
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122, 11539Ϫ11540.
-Mannitol is the chiral starting material for the synthesis of
the RoPHOS ligands, too: J. Holz, M. Quirmbach, U. Schmidt,
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8031Ϫ8034.
[12]
[13]
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[14]
[15]
1
mined by means of H NMR spectroscopy.
1997, 27, 1711Ϫ1724.
[16]
X-ray Crystallography of 15a and 10f: The crystals used in this
study were mounted onto the ends of glass fibers. X-ray data were
collected with a STOE IPDS unit (Imaging Plate Diffraction Sys-
L. F. Wiggins, D. J. C. Wood, J. Chem. Soc. 1950, 1566Ϫ1575.
[17]
P. Allevi, M. Anastasia, P. Ciufredda, A. M. Sanvito, Tetrahed-
ron: Asymmetry 1994, 5, 927Ϫ934.
Eur. J. Inorg. Chem. 2002, 2614Ϫ2624
2623

A. Bayer, P. Murszat, U. Thewalt, B. Rieger
FULL PAPER
[18]
A. Bayer, U. Thewalt, B. Rieger, Eur. J. Inorg. Chem. 2002,
We assume, that Zhang. et al. received 13aϪb as syrup-like
phosphonium salts.
13aϪb were first obtained in pure state by: T. V. RajanBabu,
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W. S. Knowles, Acc. Chem. Res. 1983, 16, 106Ϫ112.
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Crystal Structures, Göttingen, 1986.
199Ϫ203.
[19]
[25]
Y.-Y. Yan, T. V. RajanBabu, J. Org. Chem. 2000, 65, 900Ϫ906.
A. K. Ghosh, S. P. McKee, W. J. Thompson, Tetrahedron Lett.
[20]
[26]
[27]
1991, 41, 5729Ϫ5732.
[21]
Y. Gao, K. B. Sharpless, J. Am. Chem. Soc. 1988, 110,
7538Ϫ7539.
[22]
[28]
[29]
B. M. Kim, K. B. Sharpless, Tetrahedron Lett. 1989, 30,
655Ϫ658.
W. Li, Z. Zhang, D. Xiao, X. Zhang, Tetrahedron Lett. 1999,
40, 6701Ϫ6701.
11aϪb,12aϪb,13aϪb were already reported in: W. Li, Z.
Zhang, D. Xiao, X. Zhang, J. Org. Chem. 2000, 65, 3489Ϫ3496.
G. M. Sheldrick, SHELXL-97, Program for the Refinement of
Crystal Structures, Göttingen, 1997.
[23]
H. D. Flack, D. Schwarzenbach, Acta Crystallogr., Sect. A
1988, 44.
[24]
Received March 11, 2002
[I02125]
2624
Eur. J. Inorg. Chem. 2002, 2614Ϫ2624