Chiral [Bis(olefin)amine]rhodium(I) complexes - Transfer hydrogenation in ethanol

Article abstract of DOI:10.1002/ejic.200900875

Bis(olefin)amines (boas) are a new class of ligands for the synthesis of transition metal complexes, which can be used in various homogeneous catalytic reactions. A simple straightforward coupling reaction between 5H-dibenzo[a,d]cyclohepten-5-yl chloride

Full text of DOI:10.1002/ejic.200900875

FULL PAPER
DOI: 10.1002/ejic.200900875
Chiral [Bis(olefin)amine]rhodium(I) Complexes – Transfer Hydrogenation in
Ethanol
Theo Zweifel,[a] David Scheschkewitz,[a] Timo Ott,[a] Matthias Vogt,[a] and
Hansjörg Grützmacher*[a]
Keywords: Asymmetric catalysis / Enantioselectivity / Ethanol / Olefin complexes / Rhodium / Transfer hydrogenation
Bis(olefin)amines (boas) are a new class of ligands for the
synthesis of transition metal complexes, which can be used
bis(olefin)imines, which were reduced to the corresponding
bis(olefin)amines. With [Rh2(µ-Cl)2(CO)4] or [Rh2(µ-Cl)2-
(C2H4)4], a complexation of these compounds was achieved
leading to chiral rhodium complexes of the type [Rh(boa)-
in various homogeneous catalytic reactions.
A simple
straightforward coupling reaction between 5H-dibenzo[a,d]-
cyclohepten-5-yl chloride (tropCl) and primary amines al-
lows the synthesis of various chiral boas. Birch reduction of
phenylalanine gives (2S)-2-amino-3-cyclohexa-1,4-dien-1-yl
propanoate, which is used for the synthesis of the bis(olefin)-
amine methyl (2S)-3-(cyclohexa-1,4-dienyl)-2-(5H-dibenzo-
[a,d]cyclohepten-5-yl-amino)propionate. Coupling between
cyclohex-3-en-1-ylamine with tropCl gives N-(cyclohex-3Ј-
en-1Ј-yl)-5H-dibenzo[a,d]cyclohepten-5-ylamine, which was
separated into its enantiomers. Bicyclic cyclohexenylamine
derivatives like bicyclo[2.2.2]oct-5-en-2-ylamine and 2-
(methoxycarbonyl)bicyclo[2.2.1]hept-5-en-3-ylamine were
likewise coupled with tropCl to give chiral bis(olefin)amines.
Alternatively, 5H-dibenzo[a,d]cyclohepten-5-ylamine (trop-
NH2) can react with cyclohexenyl ketones to give prochiral
(CO)]OTf or [Rh(boa)(PR3)]OTf. The complexes have
a
strongly distorted saw-horse-type structure (determined by
X-ray diffraction studies) and were tested in transfer hydro-
genations with ethanol/2-propanol as hydrogen donor. Only
complexes with tightly bound olefinic binding sites and a
pronounced saw-horse-type structure give significant activi-
ties. Furthermore, a phosphane ligand in trans position to the
coordinated amine function has a positive impact of the cata-
lysts performance. None of the investigated catalysts gave an
impressive enantiomeric excess (ee Ͻ 60%) in the transfer
hydrogenation of acetophenone.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2009)
benzo[a,d]cyclohepten-5-yl] [Rh(trop2NH)(PPh3)]OTf (2) is
a very efficient catalyst precursor for this reaction (see
Scheme 1), and remarkable activities (TOF50 = 500000 for
acetophenone) were achieved. In this reaction, ethanol is
converted into ethyl acetate by reaction (1).
Introduction
Asymmetric transfer hydrogenation has been the subject
of intense research during the last two decades. Transfer
hydrogenation is safer, cheaper and simpler than most other
methods of ketone reduction. It avoids the use of highly
flammable and/or reactive reagents like LiAlH4, silanes, H2,
and no high-pressure equipment is needed. The use of a
sacrificial alcohol is environmentally sound since it pro-
duces only benign byproducts, which are easily removed.
Highly active and selective catalysts are available today.[1] 2-
Propanol or formic acid/triethylamine mixtures as reduc-
tants in combination with (arene)ruthenium(II) or (cyclo-
pentadienyl)rhodium(III) complexes as catalysts are the
most popular choices so far.[2]
2 R2C=O + 2 EtOH Ǟ 2 R2HCOH + MeCOOEt
(1)
Importantly, reaction (1) is exothermic and practically
irreversible, whereas conventional transfer hydrogenation in
2-propanol is more or less thermoneutral and therefore re-
versible. Consequently, the transfer hydrogenation in eth-
anol proceeds at high substrate concentrations (2  or
higher), which are impossible to achieve in 2-propanol. Re-
cently, we showed that the same catalyst precursors 2a–c
efficiently promote the dehydrogenative coupling of
alcohols with water or amines to give carboxylic acids or
amides.[4] In these papers, propositions for the mechanisms
of these reactions are discussed in detail. It is suggested that
the catalysts precursors like 2a–c are initially deprotonated
to the corresponding rhodium amide complexes
[Rh(trop2N)(PR3)], which operate according to the Noyori–
Morris mechanism: The alcohol is hydrogen-bonded to the
Ethanol is a renewable resource, which has been used
successfully as hydrogen donor in transfer hydrogenation by
our group.[3] The cationic d8-RhI complex of bis(5H-di-
benzo[a,d]cyclohepten-5-yl)amine [trop2NH (1) with trop
referring to the trivial name “tropylidenyl” for 5H-di-
[a] Department of Chemistry and Applied Biology, ETH-Zürich,
8093 Zürich, Switzerland
E-mail: hansjoerg.gruetzmacher@inorg.chem.ethz.ch
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FULL PAPER
triflate complex [Rh(4)(CO)]OTf (6) by addition of 1 equiv.
of silver triflate. All attempts to replace the carbonyl ligand
by another ligand in this complex were unsuccessful. If a
strongly binding ligand like triphenylphosphane was added
to 5 or 6, displacement of the ligand 4 was observed in-
stead.
Scheme 2. Synthesis of 4 and the rhodium complexes 5, 6. Numbers
given in ligand 4 are the labeling key for the NMR spectroscopic
data of compounds 3–6.
Scheme 1. Trop2NH (1), [Rh(trop2NH)(PPh3)]OTf (2) and pro-
posed catalytic cycle. The benzo groups of the trop units in the
ligand are omitted for clarity and only denoted by bold lines in
this and all subsequent schemes. OTf– = trifluoromethanesulfonate
anion, BArF–
anion.
=
tetrakis[3,5-bis(trifluoromethyl)phenyl]borate
Cyclohex-3-en-1-ylamine as Ligand
A chiral bis(olefin)amine ligand resembling the trop2NH
is simply obtained by replacing one dibenzo[a,d]cyclo-
hepten-5-yl moiety by a suitable cycloheptenyl group. How-
ever, cycloheptenyl moieties are rather difficult to synthe-
size, whereas cyclohexenyl moieties are relatively easy to ac-
cess by Diels–Alder reactions, Birch reductions and other
synthetic methods. Starting from cyclohex-3-en-1-ylamine
hydrochloride (7),[7] N-cyclohex-3Ј-en-1Ј-yl-5H-dibenzo-
[a,d]cyclohepten-5-ylamine (8) was obtained by addition of
a trop moiety in good yield (see Scheme 3). Subsequently,
the two enantiomers of 8 were successfully separated on a
preparative chiral HPLC column.
amide nitrogen atom, dehydrogenated to give an amino hy-
drido complex [RhH(trop2NH)(PR3)], which in turn re-
duces the ketone. The transfer hydrogenation of imines with
formic acid as hydrogen donor is likewise an irreversible
reaction (liberation of CO2), and it was demonstrated that
this feature improves the enatioselectivity of the reaction.[5]
Thus, we became interested in extending our transfer hydro-
genation method in ethanol into an enantioselective variant
by using chiral bis(olefin)amine ligands. In this paper, we
report several approaches for the syntheses of new chiral
bis(olefin)amine ligands. Complexes with these new ligands
were tested in catalysis, and their ability to induce asym-
metry in transfer hydrogenation was studied.
Results and Discussion
Phenylalanine as Ligand Building Block
Methyl (2S)-2-amino-3-cyclohexa-1,4-dien-1-yl propano-
ate (3) is readily available from -phenylalanine by Birch
reduction and subsequent esterification.[6] Addition of a
trop moiety to yield methyl (2S)-3-(cyclohexa-1,4-dienyl)-
2-(5H-dibenzo[a,d]cyclohepten-5-yl-amino)propionate (4) is
straightforward and shown in Scheme 2. Complexation of
ligand 4 mandated the right choice of a rhodium precursor
complex. Only [Rh2(µ2-Cl)2(CO)4] reacted cleanly with 4 to
give [Rh(Cl)(4)(CO)] (5). Other precursors, including for ex-
ample [Rh2(µ2-Cl)2(C2H4)4], gave no clean product. The
Scheme 3. Synthesis of ligand 8 and complexes 9, 10. Numbers
given in ligand 8 are the labelling key for the NMR spectroscopic
chloride 5 was quantitatively converted into the cationic data of compounds 8–10.
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Chiral [Bis(olefin)amine]rhodium(I) Complexes
Rhodium complexes of 8 were easily obtained by apply- (olefin)amine ligands. Inspired by the chiral bicyclo[2.2.2]-
ing the established protocol already used for ligand 1.[3] Re- octa-2,5-diene successfully used by Carreira et al. in conju-
action with [Rh2(µ2-Cl)2(cod)2] and addition of tri- gate additions of boronic acids,[10] the synthesis of a new
phenylphosphane gave [Rh(Cl)(8)(PPh3)] (9). The chloride bicyclo[2.2.2]oct-5-en-2-ylamine was initiated. Starting
is readily abstracted with silver triflate, and [Rh(OTf)- from the natural product (R)-carvone, the ketone
(8)(PPh3)] (10) is obtained. 4-Methylcyclohex-3-en-1-one (1S,4S,8R)-8-methoxy-1,8-dimethylbicyclo[2.2.2]oct-5-en-2-
(11) and 3-methylcyclohex-3-en-1-one (14) are readily avail- one (17) is readily available.[11] The latter was treated with
able by Birch reduction of 3- or 4-methylanisole, respec- hydroxylamine hydrochloride to afford the corresponding
tively.[8] The ligands 12 and 15 were obtained by reductive oxime 18. Subsequently, the oxime 18 was reduced by so-
amination of 11 and 14 with tropNH2 by using NaB- dium/ethanol in refluxing toluene to give the desired bi-
H(OAc)3 (see Schemes 4 and 5).[9] Reaction of 12 with cyclo[2.2.2]oct-5-en-2-ylamines (not shown in Scheme 6) as
[Rh2(µ2-Cl)2(C2H4)4] afforded an insoluble precipitate, diastereoisomers in excess. Separation of these diastereoiso-
which was treated with PPh3 and subsequently silver triflate mers was possible by flash chromatography using Boc as
to give [Rh(OTf)(12)(PPh3)] (13) (Scheme 4).
protecting group for the free amines, and the tert-butyl bi-
cyclo[2.2.2]oct-5-en-2-ylcarbamates 19 and 20 were ob-
tained. After deprotection, the reaction with tropCl to the
final ligand 21 was straightforward (see Scheme 6).
Scheme 4. Synthesis of ligand 12 and complex 13. Numbers given
in ligand 12 are the labeling key for the NMR spectroscopic data
of compounds 12 and 13.
Scheme 5. Synthesis of ligand 15 and complex 16. Numbers given
in ligand 15 are the labeling key for the NMR spectroscopic data
of compounds 15 and 16.
Scheme 6. Synthesis of ligand 21 and complexes 22, 23. Numbers
given in ligand 18 are the labeling key for the NMR spectroscopic
data of compounds 17–23.
Heating of ligand 15 in toluene with [Rh2(µ2-Cl)2-
(COD2)] gave an insoluble precipitate, which was treated
with PPh3 and silver triflate to give [Rh(15)(PPh3)]OTf (16).
The resolution of ligands 12 and 15 into the pure
enantiomers was not attempted due to their disappointing
performance in transfer hydrogenation (vide infra).
Ligand 21 did not react readily with [Rh2(µ2-Cl)2-
(COD)2], but with [Rh2(µ2-Cl)2(C2H4)4] or [Rh2(µ2-Cl)2-
(CO)4] complexes 22 and 23, respectively, were obtained.
Finally, ligand 25 containing a bicyclo[2.2.1]hept-5-en-2-
yl moiety was prepared as shown in Scheme 7. The starting
material methyl (2S3R)-3-[(tert-butoxycarbonyl)amino]bi-
Unsaturated Bicyclic Amines
In order to avoid problems arising from ligands capable cyclo[2.2.1]hept-5-ene-2-carboxylate (24) was synthesized
of coordination from two different sides, we envisioned bi- by a quinidine-mediated stereoselective anhydride opening
cyclic cyclohexenylamines as building block for chiral bis- as described by Bolm et al.[12]
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Transfer Hydrogenation
All catalysts were tested in transfer hydrogenation in ace-
tophenone to yield (R)- and/or (S)-1-phenylethanol by
using 2-propanol and ethanol as hydrogen donors. The re-
sults are presented in Table 1. The best results obtained
with complex 2b described earlier are given for comparison
(Entries 1, 2).[3] Complex 10 containing a cyclohexenyl
group was the best catalyst precursor in terms of activity
either with ethanol or 2-propanol. A moderate enantio-
meric excess (ee) was also obtained, even at high conver-
sions (Table 1, Entries 5–7). Turnover numbers of up to
400000 were observed at a substrate/catalyst ratio S/C = 106
after 48 h, but no enantiomeric excess (ee) was observable
under these conditions (see Entry 6). Surprisingly, the com-
parable complexes 13 and 16 were almost inactive in the
reaction studied (Entries 8, 9). Obviously, the additional
methyl substituent at the cyclohexenyl olefin entity has a
large effect on the catalyst’s activity. This effect may be
either purely steric, or the deprotonation of the amine pre-
cursor complexes 13 or 16 did not give the corresponding
Scheme 7. Synthesis of ligand 25 from 24 and complexes 26, 27.
Numbers given in ligand 24 are the labeling key for the NMR spec- catalytically active amide complexes but yields catalytically
troscopic data of compounds 24–27.
inactive allyl complexes. Indeed, in a previous paper we
could show that in a related complex deprotonation of a
Deprotection of 24 by trifluoroacetic acid (TFA) and ad- C=Ctrop-bonded methyl group does occur leading to a
dition of 5H-dibenzo[a,d]cyclohepten-5-yl chloride (trop- fully characterized η3-bonded allyl complex.[13] Although
Cl) gave methyl (2S3R)-3-(5H-dibenzo[a,d]cyclohepten-5- we could not isolate the deprotonation product of 16 here,
ylamino)bicyclo[2.2.1]hept-5-ene-2-carboxylate (25) in a the NMR spectroscopic data obtained of a solution con-
straightforward reaction (see Scheme 7). Similar to 21, li- taining 16 and KOtBu clearly indicates that a proton is ab-
gand 25 reacted readily with [Rh2(µ2-Cl)2(C2H4)4] and stracted form the methyl group (Scheme 8). However, the
[Rh2(µ2-Cl)2(CO)4] to yield complexes 26 and 27, respec- rigid structure of the bis(olefin)amine ligand forestalls the
tively.
formation of an η3-allyl complex, and an η1-allyl binding
The chlorido complexes of 12, 15, 21 and 25 were not mode is observed instead as the NMR spectroscopic data
7
isolated and the chloride was abstracted in situ with silver of the H2C7 group suggests [δ(13C) = 59.8 (m, 1 C, CH2 );
triflate to give the corresponding triflate complexes in very δ(1H) = 4.45 (m, 2 H, CH2allyl)].
good yields (Ͼ80%). The physical properties (X-ray diffrac-
The best enantiomeric excess (ee 58%) was obtained with
tion data obtained with single crystals and NMR spectro- complex 6 containing the phenylalanine-derived ligand 4
scopic data) are briefly discussed after the next section dis- (Entry 4). However, the complex is comparatively less
cussing the catalytic performances. They prove the struc- active. The complexes obtained from ligands based on un-
tural assignments made to all complexes shown in saturated bicyclic amines performed all disappointingly. Ex-
Schemes 2, 3, 4, 5, 6, and 7.
cept for complex 27 (Entries 13, 14), which contains an un-
Table 1. Transfer hydrogenation of acetophenone with complexes of chiral tripodal bis(olefin)amine ligands (S/C denotes the substrate/
catalyst ratio).
Entry
Catalyst
Solvent
S/C
t [h]
Conversion [%]
ee [%]
1
2
3
4
5
6
7
8
9
10
11
12
13
14
[Rh(trop2NH)(PPh3)]OTF (2b)
[Rh(trop2NH)(PPh3)]OTF (2b)
[Rh(4)(CO)]OTf (6)
EtOH[a]
106
100000
1000
1000
10000
106
10000
100
100
100
100
100
100
48
1
0.8
1.5
0.1
48
0.25
1.2
1.2
1.2
1.2
1.2
1.2
2
90
99
83
75
96
40
91
Ͻ1
5
–
–
30
58
33
0
44
–
–
–
0
0
42
45
EtOH[a]
EtOH[a]
[Rh(4)(CO)]OTf (6)
iPrOH[b]
[Rh(8)(PPh3)]OTf (10)
[Rh(8)(PPh3)]OTf (10)
[Rh(8)(PPh3)]OTf (10)
[Rh(12)(PPh3)]OTf (13)
[Rh(15)(PPh3)]OTf (16)
[Rh(21)(CO)]OTf (22)
[Rh(21)(PPh3)]OTf (23)
[Rh(25)(CO)]OTf (26)
[Rh(25)(PPh3)]OTf (27)
[Rh(25)(PPh3)]OTf (27)
EtOH[a]
EtOH[a]
iPrOH[b]
EtOH, iPrOH[a,b]
EtOH, iPrOH[a,b]
EtOH, iPrOH[a,b]
EtOH, iPrOH[a,b]
EtOH, iPrOH[a,b]
EtOH[a]
0
Ͻ1
Ͻ1
66
46
iPrOH[b]
100
[a] Acetophenone 2  in EtOH, 1 mol-% KOtBu. [b] Acetophenone 0.5  in iPrOH, 1 mol-% KOtBu.
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Chiral [Bis(olefin)amine]rhodium(I) Complexes
[2.193(5) Å] was found for structure 5 (see Table 2), and in-
deed ligand 4 coordinates rather weakly and is easily dis-
placed by strong donor ligands like phosphanes (vide su-
pra). On the other hand, the range of Rh–ct1 distances pre-
viously found in the cationic complexes 2b and 2c is signifi-
cantly shorter [2.040(3)–2.133(5) Å].[3,4]
Scheme 8. Allyl complex 28 from 16. Numbers given in complex
28 are the labeling key for its NMR spectroscopic data.
usually bound ligand coordinating via the CO group of its
ester moiety (see Scheme 7 and below), no or only insignifi-
cant activities were found (Entries 10–12). A small solvent
effect on the ee was found for ethanol vs. 2-propanol.
Against our hope, lower ee values are systematically ob-
tained if ethanol is used as hydrogen donor when compared
to reactions with 2-propanol. The reason for this poorer
performance is not clear, but it may be that the higher di-
pole moment of ethanol lowers the energy difference be-
tween the two diastereoisomeric transition states leading to
lower ee values.
X-ray Diffraction Studies
The structures of complexes 5, 10, 13, 16 and 23 were
determined by X-ray diffraction studies with suitable single
crystals; the results are displayed in Figures 1, 2, 3, 4, and
5, respectively. Selected bond lengths and angles of these
structures are given in Table 2. For comparison, the data of
2b,c are also listed. Crystal data and refinement details are
given in Table 5. The chlorido complex 5 and the triflato
complex 10 crystallized with trigonal-bipyramidal struc-
tures. Complexes 13, 16 and 23 adopt “saw-horse”-type
structures similar to those observed for 2b and 2c.[3] Saw-
Figure 1. ORTEP plot (at 30% ellipsoid probability) of structure
5. Carbon-bound hydrogen atoms and one solvent molecule are
omitted for clarity. Selected bond lengths [Å] and angles [°] (ct1 =
centroid C4=C5, ct2 = centroid CA=CB): Rh1–N1 2.151(3), Rh1–
C26 1.867(4), Rh1–Cl 2.526(3), Rh1–ct1 2.074(4), Rh1–ct2
2.193(5), Rh1–C4 2.176(5), Rh1–C5 2.212(5), Rh1–CA 2.321(5),
Rh1–CB 2.282(5), C4=C5 1.430(6), CA=CB 1.396(7); N1–Rh1–
C26 174.28(12), ct1–Rh1–ct2 129.18(18).
The ct1–Rh–ct2 angles of the trigonal-bipyramidal struc-
horse (SH) structures may be viewed as trigonal pyramids tures 5 [129.2(2)°] and 10 [135.1(1)°] are about 10–15°
with one missing ligand in the equatorial plane. In contrast smaller than the ct1–Rh–ct2 angles found for the saw-horse
to classical planar tetracoordinated 16-electron complexes, structures 2b,c [144.7(4)°, 145.5(5)], 13 [144.0(1)°] and 16
this feature makes SH complexes Lewis-acidic. In all struc- [143.6(1)°]. Interestingly, the ct1–Rh–ct2 angle of structure
tures the olefin ligands – the π-acceptors – are in the equa- 23 [153.2(2)°] is 10° larger than the ct1–Rh–ct2 angles in
torial plane, and the two axial positions are occupied by the 2b,c, 13 and 16, giving structure 23 a more planar character.
σ-donors, the amino group of the respective ligands and This is due to the rigid nature of the bicyclo[2.2.2]octa-2,5-
the phosphorus center of the additional phosphane ligand. diene moiety. Whereas the angle N1–Rh–L (L = ligand
Because of its extended π-system the trop ligand [compar- trans to N1) is close to 180° for most structures, this angle
able to a (Z)-stilbene] is a superior π-accepting olefin with is compressed to 162.8(1)° and 168.8(1)° in complexes 13
a rigid concave structure. It is always in close contact to the and 16, respectively, due to the steric influence of the methyl
metal atom as indicated by the distance between Rh and group on the cyclohexenyl moiety. The two olefinic groups,
the centroid of the C4=C5trop bond, ct1. This distance is C4=C5trop and CA=CB, do not coordinate in a parallel
always shorter than the distance between Rh and the fashion to the metal center but deviate by the tilt angle θ
centroid ct2 of the other olefinic group CA=CB (see form planarity (θ measures the interplanar angle of the
Table 2).[14] Only in 10 does the cyclohexenyl moiety of li- Rh,C4,C5 and Rh,CA,CB planes; see Table 2). For struc-
gand 8 bind as well as the trop moiety. Due to steric tures 2b,c, 5, 10, 13 and 16 the values for θ vary from 5 to
reasons, the higher substituted olefinic non-trop units in li- 12°. Most distorted is clearly the structure 23 (θ = 21.1°;
gands 4, 12 and 15 bind more weakly. Furthermore, a rather see also Figure 5), again likely due to the rigidity of the
unsymmetrical coordination mode is observed, that is, the bicyclo[2.2.2]octa-2,5-diene moiety.
distances to the highest substituted olefinic carbon centers
An interesting aspect of structure 10 is the hydrogen
are generally significantly longer (see Table 2), especially in bond between one of the oxygen atoms of the triflate anion
5 (Rh–CA) and 13 (Rh–CB). The longest Rh–ct2 bond and the amine NH group. The N1–O2 distance of
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Figure 2. ORTEP plot (at 30% ellipsoid probability) of structure
10. Carbon-bonded hydrogen atoms are omitted for clarity. Se-
lected bond lengths [Å] and angles [°] (ct1 = centroid C4=C5, ct2
= centroid CA=CB): Rh1–N1 2.135(3), Rh1–P1 2.075(4), Rh1–O1
2.347(3), Rh1–ct1 2.053(4), Rh1–ct2 2.075(4), Rh1–C4 2.182(4),
Rh1–C5 2.161(4), Rh1–CA 2.210(4), Rh–CB 2.168(4), C4=C5
1.418(6), CA=CB 1.395(6), N1–O2 3.094(8); N1–Rh1–P1
177.62(9), ct1–Rh1–ct2 135.05(14).
Figure 4. ORTEP plot (at 30% ellipsoid probability) of structure
16. The noncoordinated anion, two thf molecules and carbon-
bonded hydrogen atoms are omitted for clarity. Selected bond
lengths [Å] and angles [°] (ct1 = centroid C4=C5, ct2 = centroid
CA=CB): Rh1–N1 2.1199(22), Rh1–P1 2.2815(7), Rh1–ct1
2.045(3), Rh1–ct2 2.128(3), Rh1–C4 2.151(3), Rh1–C5 2.177(3),
Rh1–CA 2.230(3), Rh–CB 2.2450(3), C4=C5 1.418(4), CA=CB
1.385(4); N1–Rh1–P1 168.79(7), ct1–Rh1–ct2 143.59(11).
Figure 3. ORTEP plot (at 30% ellipsoid probability) of structure
13. The noncoordinated anion and carbon-bonded hydrogen atoms
are omitted for clarity. Selected bond lengths [Å] and angles [°] (ct1
= centroid C4=C5, ct2 = centroid CA=CB): Rh1–N1 2.1069(15),
Rh1–P1 2.2772(4), Rh1–ct1 2.026(2), Rh1–ct2 2.165(2), Rh1–C4
2.1277(17), Rh1–C5 2.1663(17), Rh1–CA 2.2129(17), Rh–CB
2.3317(18), C4=C5 1.420(3), CA=CB 1.383(3); N1–Rh1–P1
162.84(5), ct1–Rh1–ct2 143.98(7).
Figure 5. ORTEP plot (at 30% ellipsoid probability) of structure
23. Carbon-bonded hydrogen atoms and the disordered triflate
anion are omitted for clarity. Selected bond lengths [Å] and angles
[°] (ct1 = centroid C4=C5, ct2 = centroid CA=CB): Rh1–N1
2.114(4), Rh1–P1 2.2762(15), Rh1–ct1 2.073(5), Rh1–ct2 2.153(5),
Rh1–C4 2.168(5), Rh1–C5 2.215(5), Rh1–CA 2.203(4), Rh–CB
2.320(6), C4=C5 1.418(8), CA=CB 1.393(7); N1–Rh1–
P1 176.58(12), ct1–Rh1–ct2 153.22(21).
3.094(8) Å is in the typical range of a strong N–H–O hydro- ture. In this position its influence on the stereochemical
gen interaction. Remarkably, in both structures, 13 and 16, outcome of the catalytic reaction is very limited. We as-
the methyl group on the olefin is oriented away from the sume, however, that the energy difference between the two
open side of the complex to the back of the saw-horse struc- possible diastereoisomers is small. Specifically under basic
5566
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© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2009, 5561–5576

Chiral [Bis(olefin)amine]rhodium(I) Complexes
Table 2. Selected bond lengths [Å] and angles [°] from X-ray diffraction studies of [bis(olefin)amine]rhodium complexes.
Entry
Compound
Rh–ct1
Rh–C4
Rh–C5
Rh-ct2
Rh–CA
Rh–CB ct1–Rh–ct2 N1–Rh–L[a]
θ
1
2
3
4
5
6
7
[Rh(trop2NH)(PPh3)]BArF (2b)
[Rh(trop2NH)(P(OPh)3)]OTf (2c) 2.074(4) 2.191(2) 2.193(3) 2.133(5) 2.195(4) 2.189(4)
2.040(3) 2.180(2) 2.201(2) 2.075(3) 2.241(1) 2.247(2)
144.7(4)
145.5(5)
129.2(2)
135.1(1)
144.0(1)
143.6(1)
153.2(2)
173.1(2)
170.1(4)
174.3(1)
177.6(1)
162.8(1)
168.8(1)
176.6(1)
4.7(1)
10.1(1)
13.7(1)
10.6(1)
11.4(1)
12.3(1)
21.1(1)
[Rh(Cl)(4)(CO)] (5)
[Rh(8)(PPh3)]OTf (10)
[Rh(12)(PPh3)]OTf (13)
[Rh(15)(PPh3)]OTf (16)
[Rh(21)(PPh3)]OTf (23)
2.074(4) 2.176(5) 2.212(5) 2.193(5) 2.321(5) 2.282(5)
2.053(4) 2.182(4) 2.161(4) 2.075(4) 2.210(4) 2.168(4)
2.026(2) 2.128(2) 2.166(2) 2.165(2) 2.213(2) 2.332(2)
2.045(3) 2.151(3) 2.177(3) 2.128(3) 2.230(3) 2.245(3)
2.073(5) 2.168(5) 2.215(5) 2.153(5) 2.203(4) 2.320(6)
[a] L = ligand trans to N1.
conditions, where the deprotonated forms, the amide or al-
The coordination shift differences confirm the trends in
lyl complexes, are present in the reaction equilibria, inver- rhodium–olefin bond strengths deduced from the structural
sion at the nitrogen atom and metal center can occur. In data of 5, 10 and 23. Short Rh–ct distances indicate tighter
order to assign the relative stereochemistries observed in the binding and remarkably in all complexes the trop moiety
solid-state structures of 10, 13, and 16 (see Table 3), the has the largest ∆δ value. Clearly, the special structural pre-
coordinated double bond is considered as a metallacyclop- organization and the superior π-accepting character make
ropane and its carbon atoms treated as pseudo-tetrahedral the trop unit an especially tightly bonded olefin ligand.
centers.[15] The configuration of the highest substituted car- Furthermore, the ∆δ value of the two olefinic binding sites
bon atom is then determined relative to the carbon atom in compensate each other: A small ∆δ value of the CA=CB
α-position to the nitrogen atom.
unit is counterbalanced by a large ∆δ value of the C=Ctrop
unit.
In good agreement with observations from the crystal
structures, the cyclohexenyl moiety in 8 has the largest ∆δ
value of all non-trop moieties and therefore binds most
strongly to the metal cation. The methyl-substituted cyclo-
hexenyl moieties in ligands 12 and 15 bind less tightly to
the rhodium cation. Not surprisingly, the doubly substi-
tuted olefinic carbon atoms of 4, 12 and 15 have a signifi-
cantly lower ∆δ value in agreement with the observed
longer C–Rh distances in the crystal structures. Ligands 12
and 15 show an especially small ∆δ value (albeit not re-
flected in the Rh–ct2 distances), and the methyl-substituted
cyclohexenyl moiety appears to be a weaker ligand. Based
on ∆δ, ligand 4 seems to bind only slightly weaker than
ligand 21 in the respective carbonyl complexes. As men-
tioned above, ligand 4 is readily displaced from complex 5
or 6 when a strong ligand like triphenylphosphane is
added. For the complexes with the ligands 21 and 25 this
is not observed, the carbonyl complexes 22 and 26 do not
react immediately with triphenylphosphane, and starting
from [Rh2(µ2-Cl)2(C2H4)4], the triphenylphosphane com-
plexes 23 and 27 are readily obtained. Due to its steric de-
mand and its weak bonding, ligand 4 is only compatible
with small additional ligands like CO (see Figure 1). The
olefin moiety, CA=CB, in ligand 25 is an even weaker li-
gand for rhodium(I) than the one in ligand 21, most likely
because the methyl carboxylate moiety in 25 is sterically
too demanding. Consequently, the ∆δ value for the car-
bonyl complex 26 is quite small. Most remarkably, when
the CO ligand in 26 is replaced by PPh3, a de-coordination
of the CA=CB moiety occurs, which is clearly indicated by
the negative ∆δ value observed for complex 27. The car-
bonyl group of the ester moiety binds to the metal center
instead, as is confirmed by NOESY NMR experiments. In
the η1-allyl complex 28 ∆δ is small for the trop moiety.
More importantly, CA and CB have a very large negative
∆δ value as expected for an η1-allyl complex.
Table 3. Stereochemical assignment of 10, 13 and 16.
Compound
Relative stereochemistry[a]
[Rh(8)(PPh3)]OTf (10)
[Rh(12)(PPh3)]OTf (13)
[Rh(15)(PPh3)]OTf (16)
lk,like (S,S)/(R,R)C16,C19
ul, unlike (R,S)/(S,R)C16,C20
lk, like (S,S)/(R,R)C16,C19
[a] The superscripts correspond to the labels in the crystal struc-
tures.
NMR Spectroscopic Data
The coordination shifts ∆δ = δfree ligand – δcomplex of the
resonances of the olefinic 13C nuclei correlate well with the
strength of the metal–olefin back bonding.[16] These data
are listed in Table 4 for the complexes synthesized here (6,
10, 13, 16, 22, 23, 26, 27, and 28) in comparison with those
of 2a–c. An increasing positive ∆δ value indicates a shift to
lower frequency and increasingly tight metal–olefin interac-
tion.
Table 4. Olefinic 13C NMR coordination shift differences (∆δ) of
rhodium complexes.
Entry
Compound
∆δ C4 ∆δ C5 ∆δ CA ∆δ CB
1
2
3
4
5
6
7
8
9
[Rh(trop2NH)(PPh3)]OTf (2a)
[Rh(trop2NH)(PPh3)]BArF (2b)
[Rh(trop2NH)(P(OPh)3)]OTf (2c)
[Rh(4)(CO)]OTf (6)
57
50
50
64
57
57
60
51
49
72
67
3.5
57
40
50
64
57
49
49
51
44
73
71
3.5
–
–
–
–
–
–
37
33
14
14
36
27
8
29
50
27
36
36
33
16
–0.6
–24
[Rh(8)(PPh3)]OTf (10)
[Rh(12)(PPh3)]OTf (13)
[Rh(15)(PPh3)]OTf (16)
[Rh(21)(CO)]OTf (22)
[Rh(21)(PPh3)]OTf (23)
[Rh(25)(CO)]OTf (26)
10
11
12
[Rh(25)(PPh3)]OTf (27)
[Rh(15-H)(PPh3)] (28)
–2.5
–36
Eur. J. Inorg. Chem. 2009, 5561–5576
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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5567

T. Zweifel, D. Scheschkewitz, T. Ott, M. Vogt, H. Grützmacher
FULL PAPER
ety is the most promising. However, methyl substitution at
the C=C binding sites must be avoided. As a result, com-
Conclusions
The most successful ligand is clearly the bis(olefin)amine plex 10 performed well and proved to be a notably stable
ligand 8. The precursor complex 10 showed the best cata- catalyst. Turnover numbers of up to 400000 were observed
lytic activity (up to 44% ee in short reaction times at S/C at S/C = 106 after 48 h. The more substituted bicyclic
= 10000, Table 1, Entries 5–7). This is not much different amines turned out to be problematic for the catalytic reac-
from the previously obtained results with the bis(trop)- tion, most likely because they are too rigid and perhaps also
amine ligand, trop2NH (Table 1, Entries 1, 2).[3] The struc- sterically to demanding.
ture of 10 is very similar to 2a–c, and the access to the
rhodium center is sterically not blocked. The moderate ee
values found with this precatalyst indicate that the energy
Experimental Section
difference between the two diastereoisomeric transition
states is small. This is not surprising considering its struc-
ture (Figure 2). Complex 5 was found to be catalytically
active, but lower reaction rates were observed (up to 58%
General Techniques: All manipulations of air- or moisture-sensitive
compounds were performed in flame-dried flasks under argon by
using a standard vacuum line. Air-sensitive compounds were stored
ee at S/C = 1000, Table 1, Entries 3, 4). The electron-with- and weighted in a glovebox (M Braun: lab master 130 or 150B-G).
Reactions in small quantities were performed within a glovebox.
drawing CO ligand is likely responsible for that, and we do
not exclude the possibility that the CO group itself interacts
with the basic components in the reaction mixture (alcohol-
ates), which would evidently lower the concentration of the
intermediates in the catalytic cycle. The ligand 4 on this
Chemicals: Solvents were distilled under argon from sodium/benzo-
phenone (thf, diethyl ether), sodium/benzophenone/tetraglyme (n-
hexane, dme) or calcium hydride (dcm). The following organic
compounds and metal precursors were prepared according to lit-
complex is rather flexible, which explains the observed erature methods: tropCl,[19] [Rh2(µ2-Cl)2(C2H4)4],[20] [Rh2(µ2-Cl)2-
(COD)2],[21] [Rh2(µ2-Cl)2(CO)4],[22] (2S)-2-amino-3-cyclohexa-1,4-
moderate ee values. Complexes 13 and 16 of ligands bearing
methyl-substituted cyclohexenyl moieties as well as com-
plexes 22, 23 and 26 of the ligands derived from unsaturated
bicyclic amines showed only minimal activity in transfer hy-
dien-1-yl propanoate (3),[6] cyclohex-3-en-1-ylamine hydrochloride
(7),[7] tropNH2,[23] 4-methylcyclohex-3-en-1-one (11) and 3-methyl-
cyclohex-3-en-1-one (14),[8] (1S,4S,8R)-8-methoxy-1,8-dimethylbi-
cyclo[2.2.2]oct-5-en-2-one (17).[11]
drogenation. The second olefin moiety of these ligands is a
weakly binding ligand and sterically demanding. We have Physical and Analytical Measurements: NMR spectra were re-
corded with Bruker Avance 700, 500, 400 and 300 spectrometers.
The chemical shifts (δ) are measured according to IUPAC[24] and
expressed in ppm relative to tms, CFCl3, H3PO4, and Rh(acac)3 for
evidence that the methyl group in the cyclohexenyl ligands
12 and 15 is easily deprotonated. The formation of catalyti-
cally inactive allyl complexes in deprotonation/protonation
equilibria under the conditions employed for transfer hy-
drogenation not unexpectedly lowers the catalytic ac-
tivity.[17] Furthermore, the methyl group on the CA=CB
binding site in 13 and 16 is, at least in the solid state, ori-
ented to the “wrong side” and in this position would only
have a minor influence on the stereochemical outcome of
2
1H, H, 13C, 19F, 31P and 103Rh respectively. Coupling constants J
are given in Hertz [Hz] as absolute values, unless specifically stated.
The multiplicity of the signals is indicated as s, d, t, q, or m for
singlets, doublets, triplets, quartets, or multiplets, respectively. The
abbreviation br. is given for broadened signals. Quaternary carbon
atoms are indicated as Cquart, aromatic units as CHar and CHar
when not noted otherwise. The small numbers in Schemes 2, 3, 4,
the transfer hydrogenation. Interestingly, the triphenylphos- 5, 6, and 7 indicate the detailed numbering key for the NMR spec-
troscopic data of the corresponding compounds. The olefinic pro-
tons and carbon atoms of the C=Ctrop unit in the central seven-
membered ring are indicated as CHolefin and CHolefin. The benzylic
protons and carbon atom in the central seven-membered ring are
indicated as CHbenzyl and CHbenzyl. The seven-membered ring in
the trop unit can adopt two conformations, which are, if they can
be distinguished in the NMR spectra, listed separately as exo and
endo conformers. IR spectra were recorded with a Perkin–Elmer
Spectrum 2000 FT-IR-Raman spectrometer with KBr beam splitter
(range 500–4000 cm–1). For solid compounds the ATR technique
phane complex 27 with the cyclohexenyl moiety not coordi-
nated served as precursor to a mediocre catalyst, which is,
however, more active for transfer hydrogenations than 23
(see Table 1, Entries 13, 14). The reason for that is unclear,
but possibly the reaction proceeds by another mechanism
than the one depicted in Scheme 1, which is assumed to be
operative with the amides derived from complexes 2a–c.
Our results indicate that very active transfer hydrogena-
tion catalysts with rhodium(I) and a bis(olefin)amine ligand
can be obtained with C=C binding sites firmly bound to was applied. The absorption bands are described as follows: very
strong (vs), strong (s), medium (m), weak (w), or broad (br.). Op-
tical rotation was measured at 589 nm (Na/Hal) and room tempera-
ture (22 °C) with a Perkin–Elmer 341 polarimeter by using a 10 cm
cell and a concentration of 1 mg/1 mL (c = 1.0) in the given solvent
where not stated otherwise. Gas chromatography was performed
with a Hewlett Packard HP 6890 Series GC system equipped with
an EPC split splitless injector, H2 as carrier gas and a flame ioniza-
tion detector. Experimental details of the separation into pure
enantiomers for 8 is given below, in the experimental part of the
compound. High-resolution MALDI MS was measured by the
the metal center. In addition, a phosphane ligand in one of
the axial positions opposite to the NH function has a posi-
tive impact on the catalyst’s performance. As a conse-
quence, trigonal-bipyramid (TP) or saw-horse (SH) type
structures result, which we believe are crucial for high ac-
tivities. Note, that a related complex, where a TP or SH
structure is impeded by steric constraints in the ligand
backbone and a planar structure is enforced, is inactive.[18]
Of the four bis(olefin)amine ligand types studied here for
asymmetric transfer hydrogenation, the cyclohexenyl moi- mass spectroscopy service of ETH Zürich. Elemental analyses were
5568 Eur. J. Inorg. Chem. 2009, 5561–5576
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© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Chiral [Bis(olefin)amine]rhodium(I) Complexes
Table 5. Crystal data and summary of data collection and refinement details for 5, 10, 13, 16 and 23.
5
10
13
16
23
Empirical formula
Formula mass
T [K]
Crystal system
Space group
a [Å]
b [Å]
c [Å]
α [°]
β [°]
C26H24ClNO3Rh·CH2Cl2 C40H36F3NO3PRhS·CH2Cl2 C41H38F3NO3PRhS C44H46F3NO3PRhS·2C2H4O C45H44F3NO4PRhS
621.75
298(2)
886.56
200(2)
triclinic
815.90
100(2)
959.90
100(2)
885.76
293(2)
monoclinic
P2(1)
8.909(10)
15.030(17)
10.475(11)
90
tetragonal
I41/a
37.1992(6)
37.1992(6)
10.3140(3)
90
monoclinic
P21/c
16.1780(12)
13.5047(10)
20.9085(15)
90
orthorhombic
P2(1)2(1)2(1)
9.5792(5)
18.372(4)
24.792(8)
90
¯
P1
10.5178(9)
14.1050(12)
14.5010(12)
64.3720(10)
82.892(2)
94.50(2)
90
90
90
104.1330(10)
90
90
90
γ [°]
78.926(2)
V [Å3]
1398(3)
2
1901.5(3)
2
14272.3(5)
16
4429.8(6)
4
4363.3(16)
4
Z
ρcalcd. [gcm–3]
Crystal size [mm]
2θmax [°]
Ntot
1.477
1.548
1.518
1.439
1.349
0.29ϫ0.29ϫ0.12
56.04
0.48ϫ0.23ϫ0.07
52.76
0.28ϫ0.19ϫ0.15
56.60
0.26ϫ0.23ϫ0.10
56.62
0.27ϫ0.24ϫ0.11
68.84
11361
17067
72422
44796
43321
N (Rint
Final R indices
[IϾ2σ(I)]
R indices
(all data)
)
5919 (0.0190)
R1 = 0.0303,
wR2 = 0.0783
R1 = 0.0352,
wR2 = 0.0812
7744 (0.0459)
R1 = 0.0516,
wR2 = 0.1019
R1 = 0.0616,
wR2 = 0.1067
8868 (0.0441)
R1 = 0.0310,
wR2 = 0.0724
R1 = 0.0346,
wR2 = 0.0742
10990 (0.0333)
R1 = 0.0475,
wR2 = 0.1193
R1 = 0.0546,
wR2 = 0.1242
17012 (0.0846)
R1 = 0.0501,
wR2 = 0.1428
R1 = 0.1534,
wR2 = 0.1500
performed by the microanalytical laboratory of the ETH Zürich.
X-ray diffraction was measured with an Oxford XCalibur or a
Bruker SMART Apex diffractometer with CCD area detector.
Structures were refined by direct methods against full matrix (ver-
sus F2) using Bruker AXS SHELXTL 6.14 sofware. Details are
NMR (700 MHz, CDCl3): δ = 1.87 (dt, 2JHH = 22.0, 3JHH = 8.0 Hz,
1 H, CH2 ), 2.15 (dd, JHH = 13.3, JHH = 10.8 Hz, 1 H, CH2 ),
6
2
3
3
2
3
3
2.23 (dd, JHH = 13.3, JHH = 3.6 Hz, 1 H, CH2 ), 2.25 (m, 1 H,
6
9
3
CH2 ), 2.59 (br., 1 H, NH), 2.71 (m, 2 H, CH2 ), 2.99 (dd, JHH
=
10.7, JHH = 4.6 Hz, 1 H, CH2), 3.73 (s, 3 H, OCH3), 4.88 (s, 1 H,
3
listed
in
Table 5.
CCDC-718261
(5),
-718097
(10), CHbenzyl), 5.39 (br. s, 1 H, CH5), 5.61 (m, 1 H, CH8), 5.73 (m, 1
3
3
-723520 (13), -723657 (16) and -718036 (23) contain the supplemen-
tary crystallographic data for this paper. These data can be ob-
tained free of charge from The Cambridge Crystallographic Data
Centre via www.ccdc.cam.ac.uk/data_request/cif.
H, CH7), 6.95 (d, JHH = 11.9 Hz, 1 H, CHolefin), 6.99 (d, JHH
=
=
11.9 Hz, 1 H, CHolefin), 7.27–7.40 (m, 7 H, CHar), 7.46 (d, JHH
3
7.6 Hz, 1 H, CHar) ppm. 13C{1H} NMR (176 MHz, CDCl3): δ =
9
6
3
26.9 (s, 1 C, CH2 ), 27.7 (s, 1 C, CH2 ), 41.1 (s, 1 C, CH2 ), 51.8
(s, 1 C, OCH3), 55.2 (s, 1 C, CH2), 67.5 (s, 1 C, CHbenzyl), 123.3 (s,
1 C, CH5), 123.6 (s, 1 C, CH7), 124.1 (s, 1 C, CH8), 127.1 (s, 1 C,
CHar), 127.2 (s, 1 C, CHar), 128.2 (s, 1 C, CHar), 129.0 (s, 1 C,
CHar), 129.4 (s, 1 C, CHar), 129.8 (s, 1 C, CHar), 129.9 (s, 1 C,
CHar), 130.1 (s, 1 C, CHar), 130.2 (s, 1 C, CHolefin), 130.4 (s, 1 C,
C4), 130.5 (s, 1 C, CHolefin), 133.5 (s, 1 C, Cquart), 133.5 (s, 1 C,
Cquart), 139.0 (s, 1 C, Cquart), 139.4 (s, 1 C, Cquart), 174.7 (s, 1 C,
C1) ppm. exo conformer: 1H NMR (700 MHz, CDCl3): δ = 1.87
Catalysis. Ethanol: A 2  solution of the substrate in dry ethanol
was prepared in a Schlenk tube under argon. The catalyst was
added as solid under a stream of argon. Then 1 mol-% KOtBu was
added under a stream of argon. The reaction was monitored by
NMR spectroscopy by taking samples periodically. 2-Propanol: A
0.5  solution of the substrate in dry 2-propanol was prepared in
a Schlenk tube under argon. The catalyst was added either as solid
or as solution in thf or 2-propanol. For low catalyst loadings
(Ͼ0.1 mol-%) the solution was degassed by three pump-freeze-thaw
cycles. Then 1 mol-% of the base (K2CO3 or KOtBu) was added
under a stream of argon. The reaction was monitored by NMR
spectroscopy or GC by taking samples periodically. Separation of
(R)-, (S)-1-Phenylethanol and Acetophenone: Column: Machery &
Nagel Lipodex E (25 mϫ0.32 mmϫ0.25 µm), carrier gas: H2, tem-
perature: 1 min 70 °C then 1 °C/min to 110 °C, H2 pressure: 0.50
bar, retention times: acetophenone: 26.0 min, (S)-1-phenylethanol
31.0 min, (S)-1-phenylethanol 31.7 min.
6
6
3
(m, 1 H, CH2 ), 2.27 (m, 1 H, CH2 ), 2.47 (m, 1 H, CH2 ), 2.52
3
9
(m, 1 H, CH2 ), 2.59 (s, 1 H, NH), 2.71 (m, 1 H, CH2 ), 2.78 (m,
1 H, CH2 ), 3.58 (m, 1 H, CH2), 3.62 (s, 3 H, OCH3), 4.06 (s, 1 H,
9
CHbenzyl), 5.67 (br. s, 1 H, CH5), 5.76 (m, 2 H, CH7,8), 7.21 (m, 2
H, CHolefin), 7.35 (m, 6 H, CHar), 7.63 (d, JHH = 7.6 Hz, 1 H,
3
CHar), 7.69 (d, JHH = 7.9 Hz, 1 H, CHar) ppm. 13C{1H} NMR
3
6
9
(176 MHz, CDCl3): δ = 27.0 (s, 1 C, CH2 ), 29.4 (s, 1 C, CH2 ),
42.3 (s, 1 C, CH2 ), 51.6 (s, 1 C, CH2), 57.9 (s, 1 C, OCH3), 58.8
3
(s, 1 C, CHbenzyl), 121.6 (s, 1 C, CHar), 122.6 (s, 1 C, CHar), 122.6
(s, 1 C, CH5), 124.0 (s, 1 C, CH7) 124.1 (s, 1 C, CH8), 125.6 (s, 1
C, CHar), 125.6 (s, 1 C, CHar), 127.6 (s, 1 C, CHar), 127.7 (s, 1 C,
CHar), 128.5 (s, 1 C, CHar), 128.6 (s, 1 C, CHar), 131.0 (s, 1 C,
CHolefin), 131.1 (s, 1 C, CHolefin), 131.2 (s, 1 C, C4), 133.5 (s, 1 C,
Cquart), 134.1 (s, 1 C, Cquart), 139.3 (s, 1 C, Cquart), 140.2 (s, 1 C,
Methyl (2S)-3-(Cyclohexa-1,4-dienyl)-2-(5H-dibenzo[a,d]cyclohepten-
5-ylamino)propionate (4): Methyl (2S)-2-amino-3-cyclohexa-1,4-
dien-1-ylpropanoate (3) (7.0 g, 32 mmol, 1 equiv.) was suspended
in dcm (100 mL), and triethylamine (9 mL, 64 mmol, 2 equiv.) was
added. After stirring for 30 min, tropCl (7.3 g, 32 mmol, 1 equiv.)
was added. Stirring was continued for 2 h, and the reaction mixture
was washed with water (3ϫ100 mL) and dried with MgSO4. The
solvent was removed in vacuo yielding a yellow oil. The product
was purified by flash chromatography (ethyl acetate/n-hexane, 1:4).
Yield: 93%, 11 g, 30 mmol as off-white solid. M.p. 68–71 °C. [α]2D2
= –45.3 (c = 0.1, CH2Cl2). endo/exo = 9:1. endo conformer: 1H
Cquart), 175.6 (s, 1 C, C1) ppm. ATR IR: ν = 3301 (w, NH), 3027
˜
(w, CH), 2820 (w, CH), 1736 (s, CO), 1493 (w), 1464 (w), 1431 (w),
1359 (w), 1328 (w), 1286 (m), 1269 (m), 1212 (s), 1201 (m), 1189
(m), 1170 (s), 1151 (m), 1098 (m), 1080 (m), 1031 (s), 984 (m), 963
(m), 878 (m), 833 (m), 803 (s), 772 (s), 763 (m), 736 (s), 722 (m),
702 (m), 684 (m), 668 (s) cm–1. C25H25NO2 (371.47): calcd. C 80.83,
H 6.78, N 3.77; found C 80.67, H 6.84, N 3.79.
Eur. J. Inorg. Chem. 2009, 5561–5576
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
5569

T. Zweifel, D. Scheschkewitz, T. Ott, M. Vogt, H. Grützmacher
[Rh(Cl)(CO)(4)] (5): [Rh2(µ2-Cl)2(CO)4] (200 mg, 0.51 mmol, = 65.7 Hz, 1 C, CO) ppm. 103Rh NMR (15.8 MHz, CD2Cl2): δ =
FULL PAPER
1 equiv.) was dissolved in thf (1 mL) under argon, and 4 (420 mg,
1.3 mmol, 2.2 equiv.) was added. The solution was stirred for 2 h
and layered with n-hexane. A yellow, air-stable, crystalline material
was obtained. Yield: 86%, 449 mg, 0.88 mmol. M.p. 108–111 °C
(dec). [α]2D2 = –108.0 (c = 0.1, CH2Cl2). 1H NMR (700 MHz,
–7201 ppm. ATR IR: ν = 3170 (w, NH), 2899 (w, CH), 2032 (m,
˜
CO), 1737 (s, CO), 1602 (w), 1491 (w), 1471 (w), 1432 (m), 1397
(w), 1361 (w), 1329 (m), 1309 (m), 1275 (m), 1248 (m), 1207 (s),
1159 (m), 1098 (m), 1057 (m), 1034 (s), 978 (m), 946 (w), 921 (m),
905 (m), 867 (m), 844 (w), 818 (w), 773 (s), 761 (s), 711 (m), 660
(m) cm–1. C27H25F3NO6RhS·thf0.4 (713.96): calcd. C 52.15, H 4.66,
N 1.96; found C 52.11, H 4.71, N 1.90.
2
3
3
CDCl3): δ = 2.50 (dd, JHH = 15.4, JHH = 3.2 Hz, 1 H, CH2 ),
2.67 (m, 1 H, CH2 ), 2.70 (t, 2JHH = 14.5 Hz, 1 H, CH2 ), 2.80 (m,
6
3
9
9
2
3
1 H, CH2 ) 2.87 (m, 1 H, CH2 ), 2.93 (td, JHH = 13.0, JHH
=
N-(Cyclohex-3Ј-en-1Ј-yl)-5H-dibenzo[a,d]cyclohepten-5-ylamine (8):
Cyclohex-3-en-1-ylamine hydrochloride (7) (1 g, 7.48 mmol,
1 equiv.) was suspended in dry dcm (20 mL). Triethylamine (8 mL,
57 mmol, 7 equiv.) was added and the mixture cooled to 0 °C;
tropCl (1.86 g, 8.23 mmol, 1.1 equiv.) was added and the mixture
stirred overnight. A white solid precipitated. The organic phase was
washed with a saturated NaHCO3 solution and dried with Na2SO4.
The product was purified by flash chromatography on silica gel
with dcm. Yield: 69%, 1.48 g, 5.15 mmol.
4.0 Hz, 1 H, CH2), 3.42 (m, 1 H, CH2 ), 3.87 (s, 3 H, OCH3), 3.92
6
(br. s, 1 H, CH5), 4.45 (s, 1 H, NH), 4.46 (s, 1 H, CHbenzyl), 5.25
3
2
3
(dd, JHH = 9.2, JRhH = 2.1 Hz, 1 H, CHolefin), 5.28 (dd, JHH
=
=
2
3
3
9.0, JRhH = 2.00 Hz, 1 H, CHolefin), 5.74 (dd, JHH = 7.3, JHH
3
3
2.8 Hz, 1 H, CH7) 5.84 (dd, JHH = 10.0, JHH = 2.1 Hz, 1 H,
3
3
CH8), 7.22 (t, JHH = 6.4 Hz, 2 H, CHar), 7.28 (td, JHH = 7.5,
3
3
4JHH = 1.2 Hz, 1 H, CHar), 7.33 (td, JHH = 7.5, JHH = 1.2 Hz, 1
3
3
H, CHar), 7.40 (dt, JHH = 7.5, JHH = 1.2 Hz, 1 H, CHar), 7.45
(td, 3JHH = 7.6, 3JHH = 1.2 Hz, 1 H, CHar), 7.64 (t, 3JHH = 6.6 Hz,
2 H, CHar) ppm. 13C{1H} NMR (176 MHz, CDCl3): δ = 29.6 (s,
Analytical HPLC: Separation of enantiomers was successful with
an Agilent 1100 series HPLC using a Chiralcel OJ column, n-hex-
ane/2-propanol (80:20), 1 mL/min. Retention time: enantiomer A:
18.3 min, enantiomer B: 26.7 min.
9
6
3
1 C, CH2 ), 30.9 (s, 1 C, CH2 ), 38.2 (s, 1 C, CH2 ), 53.1 (s, 1 C,
OCH3), 56.6 (s, 1 C, CH2), 61.1 (d, 1JRhC = 11.3 Hz, 1 C, CHolefin),
1
63.7 (d, JRhC = 8.6 Hz, 1 C, CHolefin), 66.7 (s, 1 C, CHbenzyl), 78.7
1
1
(d, JRhC = 8.6 Hz, 1 C, CH5), 98.0 (d, JRhC = 4.8 Hz, 1 C, C4),
123.4 (s, 1 C, CH7), 125.8 (s, 1 C, CH8), 126.6 (s, 1 C, CHar), 126.8
(s, 1 C, CHar), 127.8 (s, 1 C, CHar), 128.7 (s, 1 C, CHar), 129.2 (s,
1 C, CHar), 129.3 (s, 1 C, CHar), 129.6 (s, 1 C, CHar), 129.8 (s, 1
C, CHar), 133.4 (s, 1 C, Cquart), 134.4 (s, 1 C, Cquart), 137.6 (s, 1 C,
Preparative HPLC: The product (50 mg) was separated by prepara-
tive HPLC [Gilson (306 pump, 156 UV/Vis detector, automatic
sample collector), Diacel Chiralcel OJ column, n-hexane/2-propa-
nol (85:15), 15 mL/min]. Retention time: enantiomer A: 18.3 min,
enantiomer B: 29.7 min. Enantiomeric purity was checked by ana-
lytical HPLC; it was Ͼ99% for both enantiomers. Yield of the sep-
aration: enantiomer A: 44%, 22 mg, enantiomer B: 32%, 17 mg,
both as colorless oils. In order to obtain reasonable amounts of
enantiomeric purity, the separation was repeated several times. M.p.
88 °C. Enantiomer A: [α]2D2 = +37.8 (c = 0.1, CH2Cl2). Enantio-
mer B: [α]2D2 = –38.0 (c = 0.1, CH2Cl2). endo/exo (9:1). endo con-
2
Cquart), 138.1 (d, JRhC = 1.3 Hz, 1 C, Cquart), 171.1 (s, 1 C, C1),
1
186.2 (d, JRhH = 64.1 Hz, 1 C, CO) ppm. ATR IR: ν = 3170 (w,
˜
NH), 3043 (w, CH), 2899 (w, CH), 2032 (m, CO), 1738 (s, CO),
1602 (w), 1490 (m), 1471 (m), 1432 (m), 1397 (w), 1360 (m), 1348
(m), 1329 (m), 1269 (m), 1248 (m), 1217 (s), 1191 (m), 1163 (m),
1098 (m), 1075 (w), 1056 (m), 1034.36 (s), 1009 (m), 978 (m), 946
(m), 922 (m), 905 (m), 894 (m), 868 (m), 843 (m), 818 (w), 773 (s),
763 (s), 747 (m), 712 (m), 660 (m) cm–1. C26H25ClNO3Rh (537.84):
calcd. C 58.06, H 4.68, N 2.60; found C 57.92, H 4.72, N 2.61.
1
former: H NMR (400 MHz, CDCl3, 223K): δ = 1.2–1.5 (m, 1 H,
CH2), 1.7–2.2 (m, 4 H, CH2), 2.3–2.5 (m, 1 H, CH2), 2.83 (br. s, 1
H, NH), 4.36 (s, 1 H, CHNH), 5.03 (s, 1 H, CHbenzyl), 5.56 (m, 2
H, C3 and C4), 7.09 (s, 2 H, CHolefin), 7.2–7.7 (m, 8 H, CHar) ppm.
13C{1H} NMR (101 MHz, CDCl3, 223K): δ = 25.1 (s, 1 C, CH2),
29.3 (s, 1 C, CH2), 32.4 (s, 1 C, CH2), 49.5 (s, 1 C, CHNH), 65.4
(s, 1 C, CHbenzyl), 125.5 (s, 1 C, CH3), 127.5 (s, 1 C, CH4), 127.6
(s, 1 C, CHar), 127.6 (s, 1 C, CHar), 129.4 (s, 1 C, CHar), 129.5 (s,
1 C, CHar), 130.0 (s, 1 C, CHar), 130.0 (s, 1 C, CHar), 130.5 (s, 1
C, CHar) 130.5 (s, 1 C, CHar), 131.0 (s, 2 C, CHolefin), 133.3 (s, 1
C, Cquart), 133.4 (s, 1 C, Cquart), 139.7 (s, 1 C, Cquart), 139.9 (s, 1 C,
[Rh(CO)(4)]OTf (6): [Rh(Cl)(CO)(4)] (5) (421 mg, 0.83 mmol,
1 equiv.) and AgOTf (223 mg, 0.91 mmol, 1.1 equiv.) were dissolved
in dcm (20 mL). The reaction mixture was stirred for 12 h and then
filtered through Celite. The yellow dcm solution was concentrated
to 5 mL under reduced pressure. The solution was layered with
hexane, and the product was obtained as air-sensitive yellow pow-
der. Yield: 89%, 478 mg, 0.73 mmol. M.p. 162–165 °C (dec). [α]2D2
= –143.7 (c = 0.1, CH2Cl2). 1H NMR (500 MHz, CD2Cl2): δ =
1
Cquart) ppm. exo conformer: H NMR (400 MHz, CDCl3, 223K):
2
3
3
2.53 (dd, JHH = 15.6, JHH = 13.4 Hz, 1 H, CH2 ), 2.67 (m, 1 H,
δ = 1.2–1.5 (m, 1 H, CH2), 1.7–2.2 (m, 4 H, CH2), 2.3–2.5 (m, 1
H, CH2), 2.83 (br. s, 1 H, NH), 4.36 (s, 1 H, CHNH), 5.06 (s, 1 H,
CHbenzyl), 5.63 (m, 2 H, CHolefin), 7.19 (s, 2 H, CHolefin), 7.2–7.7
(m, 8 H, CHar) ppm. MS (EI): m/z (%) = 54.1 (40), 79.1 (15), 81.1
3
9
6
3
CH2 ), 2.72 (m, 2 H, CH2 ), 2.73 (m, 1 H, CH2 ), 3.11 (dt, JHH
=
12.5, 3JHH = 3.7 Hz, 1 H, CH2), 3.26 (m, 1 H, CH2 ), 3.90 (s, 3 H,
6
OCH3), 4.47 (br., 1 H, NH), 4.48 (br., 1 H, 1 H, CH5), 4.65 (s, 1
H, CHbenzyl), 5.47 (dd, JHH = 9.0, JRhH = 1.0 Hz, 1 H, CHolefin),
3
2
(15), 165.0 (20) 191.1 (100) [trop+], 287.2 (8) [M+]. ATR IR: ν =
˜
3
2
5.76 (dd, JHH = 9.0, JRhH = 2.8 Hz, 1 H, CHolefin), 5.80 (m, 1 H,
3022 (w), 2914 (w), 2817 (w), 1653 (w), 1483 (w), 1449 (w), 1432
(w), 1389 (w), 1355 (w), 1265 (w), 1199 (w), 1155 (w), 1127 (w),
1101 (m), 1038 (m), 953 (w), 931 (w), 873 (m), 853 (w), 835 (m),
797 (s), 768 (m), 748 (s), 733 (s), 696 (m), 654 (m), 636 (m), 606
(m) cm–1. C21H21N (287.40): calcd. C 87.48, H 7.36, N 4.87; found
C 87.48, H 7.41, N 4.84.
CH7), 5.92 (m, 1 H, CH8), 7.29 (dt, JHH = 7.3, JHH = 1.8 Hz, 2
3
4
H, CHar), 7.36 (td, JHH = 7.5, JHH = 1.1 Hz, 1 H, CHar) 7.42–
3
4
7.49 (m, 3 H, CHar) 7.67 (d, JHH = 7.7 Hz, 2 H, CHar) ppm.
3
13C{1H} NMR (126 MHz, CD2Cl2): δ = 30.4 (s, 1 C, CH2 ), 31.0
9
6
3
(s, 1 C, CH2 ), 38.4 (s, 1 C, CH2 ), 53.7 (s, 1 C, OCH3), 57.3 (s, 1
C, CH2), 67.4 (s, 1 C, CHbenzyl), 67.5 (m, 1 C, CHolefin), 67.5 (m, 1
C, CHolefin), 85.4 (m, 1 C, CH5), 102.3 (m, 1 C, C4), 120.4 (q, JCF [Rh(Cl)(8)(PPh3)] (9): [Rh2(µ2-Cl)2(COD)2] (380 mg, 0.77 mmol,
1
= 320.1 Hz, 1 C, CF3), 123.8 (s, 1 C, CH7), 126.1 (s, 1 C, CH8),
1 equiv.) and 8 (446 mg, 1.55 mmol, 2.02 equiv.) were dissolved in
127.9 (s, 1 C, CHar), 128.1 (s, 1 C, CHar), 128.4 (s, 1 C, CHar), dcm (5 mL) under argon. Over the course of 72 h a red solid pre-
129.2 (s, 1 C, CHar), 129.7 (s, 1 C, CHar), 130.5 (s, 1 C, CHar), cipitated. The mother liquor was decanted and the solid dried in
130.6 (s, 1 C, CHar), 130.7 (s, 1 C, CHar), 134.7 (s, 1 C, Cquart
)
high vacuum to yield a very insoluble substance assumed to be the
2
134.7 (d, JRhC = 1.4 Hz, 1 C, Cquart) 136.1 (s, 1 C, Cquart), 137.0 (crude) dimer [Rh2(µ2-Cl)2(8)2] (605 mg, 1.42 mmol, 0.92 equiv.).
(d, JRhC = 1.9 Hz, 1 C, Cquart), 170.9 (s, 1 C, C1), 185.8 (d, JRhC
To a suspension of [Rh2(µ2-Cl)2(8)2] (605 mg, 0.7 mmol, 1 equiv.)
2
1
5570
www.eurjic.org
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2009, 5561–5576

Chiral [Bis(olefin)amine]rhodium(I) Complexes
in dcm (4 mL) PPh3 (390 mg, 1.48 mmol, 2.1 equiv.) was added, in dry dcm (10 mL). NaBH(OAc)3 (3.42 g, 16.1 mmol, 1.4 equiv.)
and an orange solution formed after 10 min. Addition of n-hexane
was added and the turbid solution stirred for 12 h. The reaction
precipitated the orange-red, air-stable product complex was quenched by addition of a saturated aqueous NaHCO3 solu-
[Rh(Cl)(cyhtropNH)(PPh3)], which was isolated by filtration fol-
tion (20 mL). The organic phase was separated and the aqueous
phase extracted twice with dcm (10 mL). The organic phase was
lowed by drying under vacuum. Yield: 84%, 893 mg, 1.3 mmol.
1
M.p. Ͼ230 °C (dec.). H NMR (300 MHz, CDCl3): δ = –0.38 (m, dried with Na2SO4. The product was purified by flash chromatog-
1 H, CH6), 0.46 (m, 1 H, CH2), 0.90 (m, 1 H, CH2), 1.00 (m, 1 H,
raphy on silica gel (ethyl acetate/n-hexane, 1:4). Yield: 89%, 3.12 g,
NH), 1.19 (m, 1 H, CH6), 2.16 (m, 1 H, CH1), 2.2 (m, 1 H, CH5), 10.28 mmol as colorless oil. endo/exo = 7:3. endo conformer: 1H
2.3 (m, 1 H, CH5), 4.06 (m, 1 H, CHbenzyl), 4.70 (t, J = 8.5 Hz, 1
NMR (700 MHz, CDCl3): δ = 1.38–1.42 (m, 1 H, CH25 or 6), 1.60
H, CHolefin), 4.75 (m, 1 H, CH4), 4.95 (m, 1 H, CH3), 5.50 (m, 1 (s, 3 H, CH3), 1.70–1.75 (m, 1 H, CH2 ), 1.75–1.80 (m, 1 H,
H, CHolefin), 6.10–6.20 (m, 3 H, CHar), 6.86–7.38 (m, 15 H, CHar), CH25 or 6), 1.86–2.00 (m, 1 H, CH25 or 6), 1.89 (br. s, 1 H, NH),
2
7.60–8.04 (m, 5 H, CHar) ppm. 13C{1H} NMR (75.5 MHz, CDCl3): 1.79–2.05 (m, 1 H, CH25 or 6), 2.09 (d, 2JHH = 16.5 Hz, 1 H, CH2 ),
2
δ = 20.1 (d, J = 8.3 Hz, 1 C, CH5), 28.1 (s, 1 C, CH6), 29.4 (d, J = 2.21 (m, 1 H, CH1), 5.04 (s, 1 H, CHbenzyl), 5.25 (s, 1 H, CH3), 7.07
2
3.6 Hz 1 C, CH ), 60.0 (d, J = 2.7 Hz, 1 C, CH1), 65.8 (dd, J =
(m, 2 H, CHolefin), 7.20–7.47 (m, 8 H, CHar) ppm. 13C{1H} NMR
8.2, J = 5.9 Hz, 1 C, CHolefin), 67.3 (dd, J = 8.7, J = 6.9 Hz, 1 C, (176 MHz, CDCl3): δ = 23.3 (s, 1 C, CH3), 29.3 (s, 1 C, CH25 or 6),
CH4), 69.5 (dd, J = 20.8, J = 9.4 Hz, 1 C, CHolefin), 71.1 (dd, J =
16.0, J = 9.1 Hz,1 C, CH3), 71.6 (s, 1 C, CHbenzyl), 123.9–140.2 (m,
29.4 (s, 1 C, CH25 or 6), 32.4 (s, 1 C, CH2 ), 49.6 (s, 1 C, CH1), 66.1
(s, 1 C, CHbenzyl), 119.2 (s, 1 C, CH3), 126.9 (s, 1 C, CHar), 126.9
(s, 1 C, CHar), 128.7 (s, 1 C, CHar), 128.7 (s, 1 C, CHar), 129.4 (s,
2 C, CHar), 130.0 (s, 1 C, CHar), 130.0 (s, 1 C, CHar), 130.5 (s, 1
C, CHolefin), 130.5 (s, 1 C, CHolefin), 133.2 (s, 1 C, Cquart), 133.3 (s,
2
30 C, CHar and Cquart) ppm. 31P NMR (121.5 MHz, CDCl3): δ =
1
10.6 (d, JRhP = 112.6 Hz) ppm. ATR IR: ν = 3220 (w), 3045 (w),
˜
2837 (w), 2360 (w), 2160 (w), 1977 (w), 1597 (w), 1470 (w), 1433
(m), 1090 (m), 977 (w), 876 (w), 750 (s), 696 (s), 621 (m) cm–1. 1 C, Cquart), 133.8 (s, 1 C, C4), 140.1 (s, 1 C, Cquart), 140.1 (s, 1 C,
C39H36ClNPRh·(CH2Cl2)0.2 (688.04): calcd. C 66.78, H 5.20, N Cquart) ppm. exo conformer 1H NMR (700 MHz, CDCl3): δ = 1.55
2,5,6
1.99; found C 67.20, H 5.29, N 1.99.
(m, 1 H, CH25,6), 1.65 (s, 3 H, CH3), 1.69–2.22 (m, 5 H, CH2
2
+ NH), 2.37 (d, J = 16.5 Hz, 1 H, CH2 ), 2.87 (m, 1 H, CH1), 4.38
[Rh(8)(PPh3)]OTf (10): [Rh(Cl)(8)(PPh3)] (9) (315 mg, 0.46 mmol,
1 equiv.) and AgOTf (124 mg, 0.48 mmol, 1.05 equiv.) were sus-
pended in dcm (5 mL) and stirred under argon for 12 h. The solu-
tion was filtered through Celite. The solution was concentrated and
layered with n-hexane, yielding orange-red crystals of the product.
Yield: 90%, 112 mg, 0.13 mmol as air-stable orange solid. M.p.
218–224 °C (dec.). Enantiomer A: [α]2D2 = –49.8 (c = 0.1, CH2Cl2),
Enantiomer B: [α]2D2 = 52.0 (c = 0.1, CH2Cl2). 1H NMR (500 MHz,
CD2Cl2): δ = 0.61 (d, J = 13.9 Hz, 1 H, CH2), 0.74 (d, J = 15.7 Hz,
1 H, CH2), 1.68–1.75 (m, 1 H, CH5), 2.12 (t, J = 12.5 Hz, 1 H,
CH5), 2.38 (t, J = 13.9 Hz, 1 H, CH6), 2.87–3.00 (m, 1 H, CH6),
(s, 1 H, CHbenzyl), 5.33 (s, 1 H, CH3), 7.20 (s, 2 H, CHolefin), 7.36
(m, 6 H, CHar), 7.68 (dd, JHH = 7.9, JHH = 2.8 Hz, 2 H, CHar)
3
4
ppm. 13C{1H} NMR (176 MHz, CDCl3): δ = 23.4 (s, 1 C, CH3),
2
29.4 (s, 1 C, CH25 or 6), 29.5 (s, 1 C, CH25 or 6), 33.0 (s, 1 C, CH2 ),
49.9 (s, 1 C, CH1), 57.0 (s, 1 C, CHbenzyl), 119.4 (s, 1 C, CH3), 122.4
(s, 1 C, CHar), 122.4 (s, 1 C, CHar), 125.5 (s, 2 C, CHar), 127.6 (s,
1 C, CHar), 127.6 (s, 1 C, CHar), 128.5 (s, 2 C, CHar), 131.1 (s, 1
C, CHolefin), 131.2 (s, 1 C, CHolefin), 133.9 (s, 1 C, Cquart), 133.9 (s,
1 C, Cquart), 134.1 (s, 1 C, C4), 140.7 (s, 1 C, Cquart), 140.8 (s, 1 C,
Cquart) ppm. ATR IR: ν = 3013 (w, CH), 2911 (w, CH), 2831 (w,,
˜
CH), 1598 (w), 1483 (w), 1437 (m), 1375 (w), 1312 (w), 1262 (m),
1201 (w), 1159 (w), 1098 (m), 1037 (m), 967 (w), 946 (w), 914 (w),
875 (w), 833 (m), 796 (s), 767 (s), 739 (s), 698 (m), 670 (m), 633
(m), 609 (m) cm–1. HRMS (MALDI, 3-HPA): found (calcd.) for
[C22H23N + H]+ 302.1908 (302.1909). C22H23N (301.42): calcd. C
74.76, H 7.67, N 2.77; found C 74.81, H 7.61, N 2.72.
3
3.08 (s, 1 H, CH1), 4.23 (br. s, 1 H, CH4), 4.64 (d, JPH = 4.0 Hz,
1 H, NH), 4.89 (d, J = 8.8 Hz, 1 H, CHolefin), 4.96 (d, J = 7.3 Hz,
3
1 H, CH3), 5.03 (d, J = 8.8 Hz, 1 H, CHbenzyl), 5.82 (dt, JHH
=
9.2, 2JRhH = 3.5 Hz, 1 H, CHolefin), 7.42–7.62 (m, 8 H, CHar), 7.47–
7.62 (m, 9 H, CHar), 7.63–7.76 (m, 6 H, CHar) ppm. 13C{1H} NMR
(126 MHz, CD2Cl2): δ = 19.0 (s, 1 C, CH6), 27.6 (s, 1 C, CH5), 34.4
(s, 1 C, CH2), 57.3 (d, JPC = 2.7 Hz, 1 C, CH1), 71.1 (s, 1 C,
3
[Rh(12)PPh3]OTf (13): 12 (250 mg, 0.83 mmol, 2.2 equiv.) was dis-
solved in thf (2 mL), and [Rh2(µ2-Cl)2(C2H4)4] (147 mg, 0.38 mmol,
1 equiv.) was added. Evolution of C2H4 and formation of a precipi-
tate were observed. After standing for 36 h, the precipitate was fil-
tered off and dried for a short time. It is a very insoluble orange
powder of the composition [Rh2(µ2-Cl)2(12)2] (312 mg, 0.35 mmol,
0.95 equiv.). The orange powder was suspended in thf (5 mL) and
PPh3 (197 mg, 0.75 mmol, 2 equiv.) added. After stirring for
30 min, a clear orange solution was obtained. AgOTf (193 mg,
0.75 mmol, 2 equiv.) was added. The suspension was stirred for 2 h,
then the thf was removed under reduced pressure and the residue
dissolved in dcm. The solution was filtered through Celite and con-
centrated to 2 mL. The red solution was layered with n-hexane
yielding the product as red microcrystalline powder, which was fil-
tered off and dried. Overall yield: 516 mg, 84%, 0.63 mmol. M.p.
1
1
CHbenzyl), 73.9 (d, JRhC = 7.6 Hz, 1 C, CHolefin), 74.1 (d, JRhC
=
14.0 Hz, 1 C, CHolefin), 77.1 (d, JRhC = 7.3 Hz, 1 C, CH4), 92.8
1
(d, JRhC = 12.2 Hz, 1 C, CH3), 120.4 (q, JCF = 320.7 Hz, 1 C,
CF3), 126.7 (s, 1 C, CHar), 126.9 (s, 1 C, CHar), 127.2 (s, 1 C, CHar),
127.6 (s, 1 C, CHar), 128.7 (d, J = 9.7 Hz, 6 C, CHar), 128.6 (s, 1
C, CHar), 129.1 (s, 1 C, CHar), 129.5 (d, J = 46.3 Hz, 3 C, Cquart),
129.3 (s, 1 C, CHar), 129.6 (s, 1 C, CHar), 130.8 (d, J = 2.4 Hz, 3
C, CHar), 134.0 (d, J = 9.7 Hz, 6 C, CHar), 134.3 (s, 1 C, Cquart),
135.9 (d, J = 1.5 Hz, 1 C, Cquart), 137.1 (s, 1 C, Cquart), 137.5 (d, J
= 2.4 Hz, 1 C, Cquart) ppm. 19F NMR (183 MHz, CD2Cl2) δ =
–78.1 (s) ppm. 31P{1H} NMR (203 MHz, CD2Cl2): δ = 39.7 (d,
1JRhP = 140.9 Hz) ppm. 103Rh NMR (15.8 MHz, CD2Cl2): δ =
1
1
–6898 (d, 1JRhP = 140.9 Hz) ppm. ATR IR: ν = 3220 (w), 3045 (w),
˜
2929 (w), 2837 (w), 1597 (w), 1482 (m), 1470 (m), 1433 (m), 1416
(w), 1349 (w), 1314 (w), 1261 (w), 1223 (w), 1191 (w), 1158 (w),
1120 (w), 1090 (m), 1070 (w), 1058 (w), 1026 (w), 996 (w), 976 (w),
910 (w), 875 (w), 857 (w), 778 (w), 749 (s), 695 (s,6 46 w), 621 (m),
579 (w), 556 (w) cm–1. C40H36F3NO3PRhS·(CH2Cl2)0.7 (861.11):
calcd. C 56.76, H 4.38, N 1.63; found C 56.81, H 4.37, N 1.58.
1
210–220 °C (dec). H NMR (700 MHz, CDCl3): δ = 0.86 (m, 2 H,
6
2
3
3
CH2 ), 1.43 (s, 3 H, CH3), 1.46 (td, JHH = JHH = 13.0, JHH
=
5
2
3
3
3.0 Hz, 1 H, CH2 ), 1.54 (td, JHH = JHH = 13.0, JHH = 3.0 Hz,
5
2
2
2
1 H, CH2 ), 2.29 (d, JHH = 15.9 Hz, 1 H, CH2 ), 2.85 (dd, JHH
= 15.9, JHH = 1.5 Hz, 1 H, CH2 ), 3.55 (s, 1 H, CH1), 4.55 (dd,
3
2
N-(4-Methylcyclohex-3Ј-en-1Ј-yl)-5H-dibenzo[a,d]cyclohepten-5-yl-
amine (12): 4-Methylcyclohex-3-en-1-one (11) (1.27 g, 11.6 mmol,
1 equiv.) and tropNH2 (2.39 g, 11.6 mmol, 1 equiv.) were dissolved
3JHH = 8.7, 2JRhH = 2.9 Hz, 1 H, CHolefin), 4.84 (s, 1 H, CH3), 5.13
4
3
(d, JPH = 8.2 Hz, 1 H, CHbenzyl), 5.23 (d, JPH = 4.9 Hz, 1 H,
NH), 5.66 (dt, JHH = 8.6, JRhH = JPH = 2.8 Hz, 1 H, CHolefin),
3
2
3
Eur. J. Inorg. Chem. 2009, 5561–5576
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
5571

T. Zweifel, D. Scheschkewitz, T. Ott, M. Vogt, H. Grützmacher
FULL PAPER
7.02 (d, 3JHH = 7.6 Hz, 1 H, CHar), 7.17–7.23 (m, 2 H, CHar), 7.27 [Rh(15)PPh3]OTf (16): 15 (150 mg, 0.5 mmol, 2.2 equiv.) and
(t, J = 7.5 Hz, 1 H, CHar), 7.34–7.39 (m, 3 H, CHar), 7.48–7.57 [Rh2(µ2-Cl)2(COD)2] (112 mg, 0.23 mmol, 1 equiv.) were dissolved
(m, 10 H, CHar), 7.60–7.64 (m, 6 H, CHar) ppm. 13C{1H} NMR
in toluene (4 mL) in a Schlenk bomb. The resulting solution was
5
6
(176 MHz, CDCl3): δ = 23.2 (s, 1 C, CH2 ), 30.5 (s, 1 C, CH2 ), heated at 100 °C for 48 h, whereby an orange precipitate formed.
2
30.8 (s, 1 C, CH3), 34.1 (s, 1 C, CH2 ), 54.8 (s, 1 C, CH1), 68.5 (s,
The solution was left to cool to room temperature, then the precipi-
1
1 C, CHbenzyl), 73.9 (d, JRhC = 8.2 Hz, 1 C, CHolefin), 82.0 (d, tate was filtered off and dried under vacuum, affording a very insol-
1JRhC = 15.5 Hz, 1 C, CHolefin), 92.7 (d, J = 5.9 Hz, 1 C, CH3), uble orange powder of the composition [Rh2(µ2-Cl)2(15)2] (167 mg,
1
120.9 (q, JCF = 320.3 Hz, 1 C, CF3), 119.9 (d, J = 10.5 Hz, 1 C,
0.19 mmol, 0.84 equiv.). This orange powder was suspended in thf
(3 mL) and PPh3 (118 mg, 0.45 mmol, 2 equiv.) added. Over the
C4), 126.9 (s, 1 C, CHar), 128.4 (s, 1 C, CHar), 128.5 (s, 1 C, CHar),
128.8 (s, 2 C, CHar), 129.0 (s, 1 C, CHar), 129.2 (s, 1 C, CHar), course of 1 h, a clear orange solution formed. AgOTf (116 mg,
129.5 (d, J = 10.1 Hz, 6 C, CHar), 129.7 (s, 1 C, CHar), 130.6 (d, J
= 43.9 Hz, 3 C, Cquart), 131.4 (d, J = 2.3 Hz, 3 C, CHar), 134.5 (d,
0.45 mmol, 2 equiv.) was added and the resulting suspension stirred
for 5 h. Then the solvent was removed under reduced pressure and
J = 10.5 Hz, 6 C, CHar), 135.5 (s, 1 C, Cquart), 136.2 (d, 1 C, Cquart), the residue dissolved in dcm. The solution was filtered through
137.8 (d, J = 1.8 Hz, 1 C, Cquart), 138.4 (d, J = 2.3 Hz, 1 C, Cquart
)
Celite and concentrated to 2 mL. The solution was layered with n-
hexane, the precipitated product filtered off and dried. Yield:
265 mg, 72%, 0.33 mmol. M.p. 180–200 °C (dec). 1H NMR
1
ppm. 31P{1H} NMR (283 MHz, CDCl3): δ = 35.24 (d, JRhP
=
153.6 Hz) ppm. 1H, 103Rh NMR (22.1 MHz, CDCl3): δ = –6958
1
2
(d, JRhP = 153.6 Hz) ppm. ATR IR: ν = 3150 (w, NH), 2938 (w,
(700 MHz, CD2Cl2): δ = 0.86 (d, 2JHH = 15.6 Hz, 1 H, CH2 ), 0.93
˜
CH), 1588 (w), 1486 (m), 1435 (m), 1373 (w), 1331 (w), 1279 (s), (d, 2JHH = 15.6 Hz, 1 H, CH2 ), 1.45 (s, 3 H, CH3), 1.56 (dtd, 2JHH
2
3
3
6
1253 (s), 1241 (s), 1222 (s), 1158 (s), 1146 (s), 1096 (m), 1070 (m),
= 14.5, JHH = 9.8, JHH = 2.1 Hz, 1 H, CH2 ), 2.19 (m, 1 H,
6
2
3
3
1027 (vs), 999 (m), 937 (w), 888 (m), 878 (m), 836 (w), 809 (w), CH2 ), 2.49 (ddd, JHH = 18.9, JHH = 9.5, JHH = 4.0 Hz, 1 H,
5
2
3
3
754 (s), 741 (s), 718 (m), 699 (s), 690 (s), 634 (vs), 611 (m) cm–1. CH2 ), 2.79 (ddd, JHH = 18.8, JHH = 9.6, JHH = 9.5 Hz, 1 H),
C41H38F3NO3PRhS·(CH2Cl2)0.3 (841.17): calcd. C 58.97, H 4.63, 3.33 (s, 1 H, CH1), 4.31 (d, JPH = 4.0 Hz, 1 H, NH), 4.37 (dd,
3
2
2
3
N 1.67; found C 58.75, H 4.61, N 1.66.
3JHH = 8.9, JRhH = 2.8 Hz, 1 H, CHolefin), 4.65 (t, JRhH = JPH
= 4.1 Hz, 1 H, CH4), 5.23 (d, JPH = 8.5 Hz, 1 H, CHbenzyl), 5.69
4
3
2
(dt, JHH = 8.9, JRhH
=
3JPH = 3.2 Hz, 1 H, CHolefin), 7.17 (dd,
N-(4-Methylcyclohex-3Ј-en-1Ј-yl)-5H-dibenzo[a,d]cyclohepten-5-yl-
amine (15): 3-Methylcyclohex-3-en-1-one (14) (0.85 g, 7.7 mmol,
1 equiv.) and tropNH2 (1.59 g, 7.7 mmol, 1 equiv.) were dissolved
in dry dcm (10 mL). NaBH(OAc)3 (2.3 g, 10.8 mmol, 1.4 equiv.)
was added and the turbid solution stirred for 12 h. The reaction
was quenched by addition of a saturated aqueous NaHCO3 solu-
tion (20 mL). The organic phase was separated and the aqueous
phase extracted twice with dcm (20 mL) The organic phase was
dried with Na2SO4. The product was purified by flash chromatog-
raphy on silica gel (ethyl acetate/n-hexane, 1:4). Yield: 71%,1.67 g,
10.28 mmol as colorless oil. endo/exo = 3:2. endo conformer: 1H
NMR (700 MHz, CDCl3): δ = 1.30–2.10 (m, 6 H, CH22,5 and 6), 1.64
(s, 3 H, CH3), 2.76 (m, 1 H, CH1), 5.05 (s, 1 H, CHbenzyl), 5.18 (s,
1 H, CH4), 7.09 (m, 2 H, CHolefin), 7.35 (m, 8 H, CHar) ppm.
4
3
3JHH = 7.2, JHH = 1.7 Hz, 1 H, CHar), 7.34 (d, JHH = 4.0 Hz, 2
H, CHar), 7.37–7.43 (m, 3 H, CHar), 7.48–7.51 (m, 1 H, CHar), 7.55
(dd, JHH = 7.2, JHH = 2.0 Hz, 1 H, CHar), 7.57–7.61 (m, 6 H,
3
4
CHar), 7.62–7.68 (m, 9 H, CHar) ppm. 13C{1H} NMR (176 MHz,
5
6
CD2Cl2): δ = 20.4 (s, 1 C, CH2 ), 26.5 (s, 1 C, CH2 ), 29.2 (s, 1 C,
2
CH3), 42.6 (s, 1 C, CH2 ), 57.3 (s, 1 C, CH1), 70.4 (s, 1 C, CHbenzyl),
71.1 (d, JRhC = 7.8 Hz, 1 C, CHolefin), 82.2 (d, JRhC = 15.0 Hz, 1
1
1
C, CHolefin), 88.7 (d, JRhC = 5.9 Hz, 1 C, CH4), 120.9 (q, JCF
=
1
1
321.3 Hz, 1 C, CF3), 122.6 (d, J = 10.2 Hz, 1 C, C3), 127.3 (s, 1 C,
CHar), 127.6 (s, 1 C, CHar), 128.4 (s, 1, CHar), 128.6 (s, 1, CHar),
129.0 (s, 2 C, CHar) 129.1 (d, J = 9.7 Hz, 6 C, CHar), 129.1 (s, 1 C,
CHar), 129.2 (s, 1, CHar), 129.6 (d, J = 20.7 Hz, 3 C, Cquart), 131.3
(d, J = 2.4 Hz, 3 C, CHar), 134.4 (d, J = 10.2 Hz, 6 C, CHar), 134.5
(s, 1 C, Cquart), 136.2 (s, 1 C, Cquart), 136.2 (s, 1 C, Cquart), 137.6 (d,
J = 2.4 Hz, 1 C, Cquart) ppm. 31P{1H} NMR (283 MHz, CD2Cl2): δ
5
13C{1H} NMR (176 MHz, CDCl3): δ = 20.4 (s, 1 C, CH2 ), 23.8
(s, 1 C, CH3), 29.2 (s, 1 C, CH22 or 6), 30.2 (s, 1 C, CH22 or 6), 50.2
(s, 1 C, CH1) 66.7 (s, 1 C, CHbenzyl), 123.9 (s, 1 C, CH4), 126.9 (s,
1 C, CHar), 128.5 (s, 2 C, CHar), 128.7 (s, 1 C, CHar), 129.5 (s, 1
C, CHar) 129.6 (s, 1 C, CHar) 130.0 (s, 1 C, CHar) 130.0 (s, 1 C,
CHar), 130.5 (s, 1 C, CHolefin), 130.6 (s, 1 C, CHolefin), 133.4 (s, 1
C, Cquart), 133.4 (s, 1 C, Cquart), 136.1 (s, 1 C, C3), 140.2 (s, 1 C,
Cquart), 140.4 (s, 1 C, Cquart) ppm. exo conformer: 1H NMR
(700 MHz, CDCl3): δ = 1.30–2.10 (m, 6 H, CH22,5 and 6), 1.74 (s, 3
1
= 35.9 (d, JRhP = 152.6 Hz) ppm. 1H, 103Rh NMR (22.1 MHz,
CD2Cl2): δ = –7027 (d, 1JRhP = 152.6 Hz) ppm. ATR IR: ν = 3141
˜
(w,, NH), 2894 (w), 1602 (w), 1479 (w), 1434 (w), 1373 (w), 1282
(m), 1253 (m), 1222 (m), 1151 (m), 1095 (m), 1064 (m), 1030 (s),
998 (m), 961 (w), 909 (w), 840 (w), 811 (w), 775 (w), 743 (m), 696
(s), 635 (s) cm–1. C41H38F3NO3PRhS·(CH2Cl2) (900.62): calcd. C
56.01, H 4.48, N 1.56; found C 55.46, H 4.45, N 1.54.
H, CH3), 3.25 (s, 1 H, CH1), 4.42 (s, 1 H, CHbenzyl), 5.66 (s, 1 H,
3
CH4), 7.22 (s, 2 H, CHolefin), 7.37 (m, 6 H, CHar), 7.74 (t, JHH
=
(1S,4S,8R)-8-Methoxy-1,8-dimethylbicyclo[2.2.2]oct-5-en-2-one Ox-
7.0 Hz, 2 H, CHar) ppm. 13C{1H} NMR (176 MHz, CDCl3): δ = ime (18): (1S,4S,8R)-8-Methoxy-1,8-dimethylbicyclo-[2.2.2]oct-5-
20.6 (s, 1 C, CH2 ), 23.8 (s, 1 C, CH3), 29.6 (s, 1 C, CH22 or 6), 30.4
en-2-one (17) (1.63 g, 9.0 mmol, 1 equiv.), sodium acetate (1.48 g,
5
(s, 1 C, CH22 or 6), 50.4 (s, 1 C, CH1), 57.2 (s, 1 C, CHbenzyl), 122.5 18 mmol, 2 equiv.) and hydroxylamine hydrochloride (1.57 g,
(s, 1 C, CHar), 122.6 (s, 1 C, CHar), 124.7 (s, 1 C, CH4), 125.5 (s, 2
C, CHar), 126.9 (s, 1 C, CHar), 127.6 (s, 1 C, CHar), 127.6 (s, 1 C,
CHar), 128.5 (s, 1 C, CHar), 131.1 (s, 1 C, CHolefin), 131.2 (s, 1 C,
CHolefin), 133.9 (s, 1 C, Cquart), 134.0 (s, 1 C, Cquart), 136.3 (s, 1 C,
22.6 mmol, 2.5 equiv.) were suspended in methanol (50 mL). The
mixture was heated at reflux for 6 h, the solvent removed under
reduced pressure and the residue dissolved in diethyl ether (50 mL),
which was washed with a saturated NaHCO3 solution and dried
C4), 140.6 (s, 1 C, Cquart), 140.8 (s, 1 C, Cquart) ppm. ATR IR: ν = with Na2SO4. The solvent was removed under reduced pressure and
˜
2922 (m, CH), 1671 (w), 1597 (w), 1560 (w), 1483 (m), 1439 (m),
the crude product recrystallized from n-hexane. Yield: 95%,
1376 (m), 1344 (w), 1315 (w), 1264 (w), 1201 (w), 1157 (w), 1124 1.668 g, 8.6 mmol. M.p. 104 °C. [α]2D2 = –454.8 (c = 0.1, CH2Cl2).
(w), 1090 (s), 1037 (m), 967 (w), 946 (w), 891 (m), 874 (m), 831 1H NMR (300 MHz, CDCl3): δ = 1.21 (s, 3 H, CH310), 1.31 (s, 3
(m), 796 (s), 767 (s), 738 (s), 651 (m), 635 (m), 623 (m) cm–1. HRMS H, CH3 ), 1.37 (d, JHH = 13.2 Hz, 1 H, CH2 ), 1.73 (d, JHH
=
9
2
7
2
(MALDI, 3-HPA): found (calcd.) for [C22H23N + H]+ 302.1907
13.2 Hz, 1 H, CH2 ), 2.05 (dd, JHH = 18.3, JHH = 3.4 Hz, 1 H,
7
2
3
(302.1909). C22H23N (301.42): calcd. C 74.76, H 7.67, N 2.77; CH2 ), 2.83 (dd, 2JHH = 18.3, JHH = 2.5 Hz, 1 H, CH2 ), 2.86 (m,
3
3
3
3
found C 74.80, H 7.60, N 2.82.
1 H, CH4), 3.19 (s, 3 H, OCH311), 5.92 (d, JHH = 8.1 Hz, 1 H,
5572
www.eurjic.org
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2009, 5561–5576

Chiral [Bis(olefin)amine]rhodium(I) Complexes
3
CH6), 6.35 (t, JHH = 7.6 Hz, 1 H, CH5), 9.14 (s, 1 H, OH) ppm.
3044 (w, CH), 2964 (m, CH), 2933 (m, CH), 2826 (w), 1682 (s,
C=O), 1529 (s, C=C), 1454 (m), 1390 (m), 1377 (m), 1365 (m), 1330
13C{1H} NMR (75 MHz, CDCl3): δ = 19.2 (s, 1 C, CH3 ), 24.8 (s,
9
1 C, CH310), 25.9 (s, 1 C, CH2 ), 40.3 (s, 1 C, CH4), 41.6 (s, 1 C, (m), 1287 (m), 1270 (m), 1248 (m), 1214 (m), 1171 (s), 1129 (m),
3
C1), 47.8 (s, 1 C, CH2 ), 49.6 (s, 1 C, OCH311), 78.6 (s, 1 C, C8), 1103 (m), 1076 (m), 1060 (s), 1051 (s), 1030 (m), 1003 (m), 975 (m),
7
134.7 (s, 1 C, CH5), 136.2 (s, 1 C, CH6), 163.8 (s, 1 C, C2) ppm.
955 (w), 926 (w), 901 (m), 879 (m), 836 (m), 786 (m), 755 (m), 744
ATR IR: ν = 3257 (w), 3140 (w), 3038 (w), 2965 (m), 2928 (m), (s), 722 (s), 674 (m), 644 (m), 613 (m) cm–1. C16H27NO3 (281.39):
˜
2827 (w), 2161 (w), 1682 (w), 1614 (w), 1435 (m), 1372 (m), 1338 calcd. C 68.29, H 9.67, N 4.98; found C 68.26, H 9.61, N 4.91. 19:
1
(w), 1321 (w), 1284 (m), 1252 (m), 1188 (m), 1164 (m), 1152 (m),
1129 (w), 1096 (w), 1072 (m), 1059 (m), 1020 (w), 992 (w), 931 (s),
[α]2D2 = –96.9 (c = 0.1, CH2Cl2). H NMR (500 MHz, CDCl3): δ =
7
9
1.04 (dd, 2JHH = 13.6, J = 1.8 Hz, 1 H, CH2 ), 1.08 (s, 3 H, CH3 ),
2
913 (s), 888 (m), 848 (m), 812 (m), 758 (m), 722 (s), 675 (m), 646 1.14 (s, 3 H, CH310), 1.47 (s, 9 H, CH314), 1.52 (dt, JHH = 13.6,
(m) cm–1. C11H17NO2 (195.26): calcd. C 67.66, H 8.78, N 7.19; 3JHH = 2.9 Hz, 1 H, CH2 ), 1.69 (d, JHH = 13.6 Hz, 1 H, CH2 ),
3
2
7
2
3
3
3
found C 67.62, H 8.78, N 7.17.
1.76 (ddd, JHH = 13.5, JHH = 11.0, JHH = 2.9 Hz, 1 H, CH2 ),
2.57 (dt, JHH = 7.2, JHH = 2.9 Hz, 1 H, CH4), 3.22 (s, 3 H,
3
3
OCH311), 3.56 (ddd, JHH = 10.0, JHH = 9.5, JHH = 2.9 Hz, 1 H,
3
3
3
tert-Butyl (1S,2R,4S,8R)-(8-Methoxy-1,8-dimethylbicyclo[2.2.2]oct-
5-en-2-yl)carbamate (19) and tert-Butyl (1S,2S,4S,8R)-(8-Methoxy-
1,8-dimethylbicyclo[2.2.2]oct-5-en-2-yl)carbamate (20): Sodium
(2.4 g, 103 mmol, 20 equiv.) was suspended in dry toluene (100 mL)
in a three-neck round-bottomed flask equipped with a large stir
bar, an efficient reflux condenser with an argon inlet and a drop-
ping funnel charged with a solution of (1S,4S,8R)-8-methoxy-1,8-
dimethylbicyclo[2.2.2]oct-5-en-2-one oxime (18) (1 g, 5.15 mmol,
1 equiv.) in toluene (50 mL). The toluene was refluxed until a fine
suspension of sodium was obtained. Then the solution of the oxime
was added dropwise over 15 min. The reaction mixture was re-
fluxed for another 15 min and dry ethanol (20 mL) added carefully
to the hot solution until all the sodium had reacted. The solution
was cooled in an ice bath and acidified with 4  HCl (27 mL).
All volatiles were removed under reduced pressure and the solid
dissolved in as little water as possible. The aqueous phase was ex-
tracted with n-hexane to remove impurities and then basified with
sodium hydroxide. The crude amine was extracted with diethyl
ether (5ϫ20 mL) and the organic phase dried with pulverized po-
tassium hydroxide. The solvent was removed under reduced pres-
sure. Attention: the amine is quite volatile and should not be dried
under high vacuum. It can be purified by column chromatography
(SiO2; dcm/ethanol, 5:1) but the yield obtained was poor. There-
fore, the amine was protected with a Boc group, which simplified
the isolation. Crude (1S,2RS,4S,8R)-8-methoxy-1,8-dimethylbicy-
clo[2.2.2]oct-5-en-2-ylamine (790 mg, 4.36 mmol, 85%) was dis-
solved in dry dcm (8 mL), and triethylamine (0.8 mL, 5.7 mmol,
1.3 equiv.) and di-tert-butyl dicarbonate (1050 mg, 4.8 mmol,
1.1 equiv.) were added. The mixture was stirred overnight. The or-
ganic phase was washed with an aqueous solution of sodium car-
bonate and dried with Na2SO4. The diastereoisomers were sepa-
rated by chromatography on silica gel (n-hexane/ethyl acetate, 10:1)
and dried under high vacuum. The compounds did not absorb well
the UV detection light, and stains (ninhydrin, anisaldehyde) were
used. 20: Rf = 0.32. Yield: 61%, 748 mg, 2.66 mmol as white solid.
19: Rf = 0.43. Yield: 29%, 355 mg, 1.26 mmol as colorless oil. Yield
combined: 90%, 1103 mg, 3.92 mmol. 20: M.p. 73 °C. [α]2D2 = –76.3
(c = 0.1, CH2Cl2). 1H NMR (500 MHz, CDCl3): δ = 0.77 (dt, 2JHH
CH2), 4.92 (d, JHH = 9.5 Hz, 1 H, NH), 5.98 (d, JHH = 8.1 Hz,
3
3
1 H, CH6), 6.24 (dd, JHH = 8.0, JHH = 7.2 Hz, 1 H, CH5) ppm.
3
3
13C{1H} NMR (126 MHz, CDCl3): δ = 21.9 (s, 1 C, CH3 ), 25.1
9
(s, 1 C, CH310), 28.9 (s, 3 C, CH314), 31.3 (s, 1 C, CH2 ), 39.4 (s, 1
3
C, CH4), 40.1 (s, 1 C, C1), 44.5 (s, 1 C, CH2 ), 49.9 (s, 1 C, OCH311),
7
50.3 (s, 1 C, CH2), 79.1 (s, 1 C, C8), 79.2 (s, 1 C, C13), 134.1 (s, 1
C, CH5), 139.7 (s, 1 C, CH6), 156.5 (s, 1 C, C13) ppm. ATR IR: ν
˜
= 3438 (w, NH), 2966 (w, CH), 2932 (w, CH), 2870 (w), 2826 (w),
1715 (s, C=O), 1497 (s, C=C), 1453 (m), 1390 (m), 1364 (m), 1322
(m), 1298 (m), 1284 (m), 1248 (m), 1209 (m), 1166 (s), 1124 (m),
1097 (m), 1065 (m), 1044 (m), 1029 (m), 992 (w), 968 (w), 931 (w),
889 (m), 844 (m), 776 (w), 760 (w), 699 (s), 677 (m) cm–1.
(1ЈS,2ЈS,4ЈS,8ЈS)-8Ј-Methoxy-1Ј,8Ј-dimethylbicyclo[2.2.2]oct-5Ј-
en-2Ј-yl-5H-dibenzo[a,d]cyclohepten-5-ylamine (21): tert-Butyl
(1S,2S,4S,8S)-(8-methoxy-1,8-dimethylbicyclo[2.2.2]oct-5-en-2-yl)-
carbamate (20) (300 mg, 1.07 mmol, 1 equiv.) was dissolved in dcm
(2 mL) and the solution cooled to 0 °C. Trifluoroacetic acid
(0.25 mL, 3.2 mmol, 3 equiv.) was added dropwise and the reaction
mixture stirred at room temperature for 4 h. The reaction was mon-
itored by TLC. Water (5 mL) was added and the reaction mixture
neutralized with K2CO3 until no further CO2 was evolved. The
aqueous phase was extracted five times with dcm (5 mL) and the
organic phase dried with potassium carbonate. The solvent was
removed under reduced pressure to yield the deprotected amine.
The amine (170 mg, 0.94 mmol, 87%) was dissolved in dcm (5 mL)
and triethylamine (0.65 mL, 4.7 mmol, 5 equiv.) added. The solu-
tion was cooled with an ice bath, and tropCl (319 mg, 1.41 mmol,
1.5 equiv.) was added. The reaction mixture was stirred for 6 h. The
organic phase was washed with aqueous sodium carbonate and the
organic phase dried with Na2SO4. The product was chromato-
graphed on silica gel with dcm containing 1–5% ethanol, starting
with 1%. After drying for a long time, a colorless solid, still con-
taining some residual solvent, was obtained. Yield: 87%, 302 mg,
0.81 mmol. M.p. 58 °C. [α]2D2 = +0.4 (c = 0.1, CH2Cl2). endo/exo =
9:1. endo conformer: 1H NMR (700 MHz, CDCl3): δ = 0.91 (dt,
2JHH = 11.6, JHH = 2.9 Hz, 1 H, CH2 ), 0.95 (s, 3 H, CH3 ), 0.99
3
3
9
= 13.2, JHH = 2.90 Hz, 1 H, CH2 ), 1.11 (s, 3 H, CH310), 1.14 (s, (d, 2JHH = 13.1 Hz, 1 H, CH2 ), 1.05 (s, 3 H, CH310), 1.14 (d, 2JHH
3
7
7
3 H, CH3 ), 1.17 (d, JHH = 13.6 Hz, 1 H, CH7), 1.45 (s, 9 H, = 13.1 Hz, 1 H, CH2 ), 2.12 (ddd, JHH = 10.1, JHH = 2.9, JHH
9
2
7
3
3
3
CH314), 1.52 (d, JHH = 13.6 Hz, 1 H, CH7), 2.54 (dt, JHH = 6.0, = 2.0 Hz, 1 H, CH2 ), 2.15 (ddd, JHH = 10.0, JHH = 9.0, JHH
=
2
3
2
2
3
3
3JHH = 2.9 Hz, 1 H, CH4), 2.65 (ddd, JHH = 13.5, JHH = 10.0,
2.9 Hz, 1 H, CH3), 2.50 (dt, 3JHH = 7.0, 3JHH = 2.9 Hz, 1 H, CH4),
2
3
3JHH = 2.9 Hz, 1 H, CH2 ), 3.18 (s, 3 H, OCH311), 3.75 (ddd, 3JHH
3.10 (s, 3 H, OCH311), 4.83 (s, 1 H, CHbenzyl), 5.73 (d, JHH
=
3
3
= 10.0, JHH = 9.5, JHH = 2.9 Hz, 1 H, CH2), 4.20 (d, JHH
=
7.9 Hz, 1 H, CH6), 6.18 (dd, 3JHH = 7.9, 3JHH = 7.0 Hz, 1 H, CH5),
3
3
3
9.5 Hz, 1 H, NH), 5.82 (d, JHH = 8.1 Hz, 1 H, CH6), 6.35 (dd, 7.03 (s, 2 H, CHolefin), 7.15–7.45 (m, 7 H, CHar), 7.54 (d, JHH
=
3
3
3JHH = 8.0, JHH = 6.2 Hz, 1 H, CH5) ppm. 13C{1H} NMR
7.9 Hz, 1 H, CHar) ppm. 13C{1H} NMR (176 MHz, CDCl3): δ =
3
(126 MHz, CDCl3): δ = 21.8 (s, 1 C, CH3 ), 25.0 (s, 1 C, CH310),
21.7 (s, 1 C, CH3 ), 24.6 (s, 1 C, CH310), 31.7 (s, 1 C, CH2 ), 39.6
9
9
3
28.9 (s, 3 C, CH314), 33.0 (s, 1 C, CH2 ), 40.5 (s, 1 C, C1), 40.5 (s,
(s, 1 C, CH4), 39.7 (s, 1 C, C1), 48.7 (s, 1 C, CH2 ), 49.4 (s, 1 C,
3
7
1 C, CH4), 47.8 (s, 1 C, CH2 ), 50.0 (s, 1 C, OCH311), 53.2 (s, 1 C,
OCH3), 57.7 (s, 1 C, CH2), 66.9 (s, 1 C, CHbenzyl), 79.0 (s, 1 C, C8),
121.8 (s, 1 C, CHar), 130.4 (s, 1 C, CHolefin), 130.6 (s, 1 C, CHolefin),
132.6 (s, 1 C, CH5), 136.6 (s, 1 C, CH6), 125–134 (11 C, CHar and
7
CH2), 79.1 (s, 1 C, C1), 79.2 (s, 1 C, C8), 135.6 (s, 1 C, CH5), 136.1
(s, 1 C, CH6), 156.1 (s, 1 C, C12) ppm. ATR IR: ν = 3315 (m, NH),
˜
Eur. J. Inorg. Chem. 2009, 5561–5576
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
5573

T. Zweifel, D. Scheschkewitz, T. Ott, M. Vogt, H. Grützmacher
Cquart) ppm. exo conformer: 1H NMR (700 MHz, CDCl3): δ = 0.87 21 (50 mg, 0.13 mmol, 2 equiv.) added. After 1 h, PPh3 (35.3 mg,
FULL PAPER
2
3
3
(dt, JHH = 12.8, JHH = 2.9 Hz, 1 H, CH2 ), 1.12 (s, 3 H, CH310), 0.13 mmol, 2 equiv.) was added. After another 1 h, AgOTf (38 mg,
2
7
2
1.24 (d, JHH = 13.4 Hz, 1 H, CH2 ), 1.39 (d, JHH = 13.4 Hz, 1
0.15 mmol, 2.2 equiv.) was added. The solvent was removed under
7
9
3
H, CH2 ), 1.60 (s, 3 H, CH3 ), 2.26 (ddd, 2JHH = 12.7, JHH = 8.3, reduced pressure, the residue was dissolved in dcm (2 mL) and fil-
3
3
3
3JHH = 2.1 Hz, 1 H, CH2 ), 2.54 (dt, JHH = 7.0, JHH = 2.9 Hz, 1
tered through Celite. The complex was crystallized from dcm/n-
H, CH4), 2.78 (dt, JHH = 7.5, JHH = 2.9 Hz, 1 H, CH2), 3.11 (s, hexane to give an air-stable orange powder. Yield: 60%, 71 mg,
3
3
3 H, OCH311), 4.18 (s, 1 H, CHbenzyl), 6.04 (d, JHH = 7.9 Hz, 1 H, 0.08 mmol, not optimized. M.p. 220–222 °C (dec.). [α]2D2 = 76.6 (c
3
CH6), 6.31 (dd, JHH = 7.9, JHH = 7.0 Hz, 1 H, CH5), 7.15 (d,
= 0.1, CH2Cl2). H NMR (500 MHz, CD2Cl2): δ = 0.04 (dd, J =
3
3
1
3JHH = 11.6 Hz, 1 H, CHolefin) 7.19 (d, JHH = 11.6 Hz, 1 H, 14.7, 4.4 Hz, 1 H, CH2 ), 0.77 (s, 3 H, CH310) 1.01 (d, J = 13.6 Hz,
3
3
CHolefin), 7.2–7.45 (m, 7 H, CHar), 7.85 (d, JHH = 7.9 Hz, 1 H,
1 H, CH2 ), 1.25 (s, 3 H, CH3 ), 1.62 (d, J = 13.9 Hz, 1 H, CH2 ),
3
7
9
7
CHar) ppm. 13C{1H} NMR (176 MHz, CDCl3): δ = 22.7 (s, 1 C, 1.70 (dd, J = 14.5, 7.9 Hz, 1 H, CH2 ), 2.22 (t, J = 4.8 Hz, 1 H,
3
CH3 ), 24.5 (s, 1 C, CH310), 31.4 (s, 1 C, CH2 ), 39.7 (s, 1 C, CH4), CH4), 3.02 (s, 3 H, OCH311), 3.18 (t, J = 7.2 Hz, 1 H, CH2), 3.44
9
3
40.4 (s, 1 C, C1), 48.8 (s, 1 C, CH2 ), 49.4 (s, 1 C, OCH311), 56.2 (d, J = 3.7 Hz, 1 H, NH), 4.58 (d, J = 6.2 Hz, 1 H, CH6), 5.09 (d,
7
(s, 1 C, CHbenzyl), 57.4 (s, 1 C, CH2), 79.0 (s, 1 C, C8), 123.7 (s, 1, J = 8.5 Hz, 1 H, CHolefin), 5.16 (d, J = 8.1 Hz, 1 H, CHbenzyl), 5.80
CHar), 130.6 (s, 1 C, CHolefin), 131.3 (s, 1 C, CHolefin), 134.3 (s, 1 (d, J = 8.8 Hz, 1 H, CHolefin), 5.96 (s, 1 H, CH5), 7.13 (d, J =
C, CH5), 136.5 (s, 1 C, CH6), 125–134 (11 C, CHar and Cquart) ppm. 7.7 Hz, 1 H, CHar), 7.35–7.45 (m, 5 H, CHar), 7.52 (t, J = 7.89 Hz,
ATR IR: ν = 3017 (w), 2924 (m), 2823 (w), 1671 (w), 1597 (w),
2 H, CHar), 7.60–7.90 (m, 9 H, CHar), 7.71–7.91 (m, 6 H, CHar)
˜
1484 (w), 1440 (m), 1366 (m), 1334 (w), 1243 (w), 1199 (w), 1157 ppm. 13C{1H} NMR (126 MHz, CD2Cl2): δ = 22.5 (s, 1 C, CH3 ),
9
3
(m), 1143 (m), 1102 (m), 1070 (m), 1038 (m), 995 (w), 945 (w), 892
23.8 (s, 1 C, CH310), 26.1 (s, 1 C, CH2 ), 40.5 (s, 1 C, CH4), 43.2
(w), 876 (w), 861 (w), 845 (m), 795 (s), 764 (s), 736 (m), 724 (s), (s, 1 C, CH2 ), 50.0 (s, 1 C, OCH311), 68.8 (s, 1 C, CHbenzyl), 70.3
678 (m), 641 (m) cm–1. HRMS (MALDI, 3-HPA): found (calcd.) (s, 1 C, CH2), 79.4 (d, J = 4 Hz, C1), 82.5 (d, J = 7.08 Hz, 1 C,
for [C26H29NO + H]+ 370.2161 (370.2165). C26H29NO (371.51): CHolefin), 87.2 (d, J = 11.7 Hz, 1 C, CHolefin), 103.3 (d, J = 7.1 Hz,
7
calcd. C 84.06, H 7.87, N 3.77; found C 83.91, H 7.97, N 3.64.
1 C, CH6), 107.6 (d, J = 12.6 Hz, 1 C, CH5), 128.1 (s, 1 C, CHar),
128.5 (s, 1 C, CHar), 129.0 (s, 1 C, CHar), 129.1 (s, 1 C, CHar),
129.4 (s, 1 C, CHar), 129.4 (s, 1 C, CHar), 129.5 (d, J = 9.8 Hz, 6
C, CHar), 129.6 (s, 1 C, CHar), 130.0 (d, J = 19.4 Hz, 3 C, Cquart),
131.9 (d, J = 2.2 Hz, 3 C, CHar), 131.9 (s, 1 C, CHar), 134.5 (d, J
= 10.2 Hz, 6 C, CHar), 135.7 (s, 1 C, Cquart), 136.3 (s, 1 C, Cquart),
136.4 (s, 1 C, Cquart), 137.4 (s, 1 C, Cquart) ppm. 31P{1H} NMR
[Rh(21)(CO)]OTf (22): [Rh2(µ2-Cl)2(CO)4] (21 mg, 0.05 mmol,
1 equiv.) was dissolved in thf (1 mL), and 21 (40 mg, 0.11 mmol,
2 equiv.) was added. After 1 h, AgOTf (31 mg, 0.12 mmol, 2 equiv.)
was added. The solvent was removed under reduced pressure and
the residue dissolved in dcm (2 mL), filtered through Celite and the
solvet removed under reduced pressure. The complex was recrys-
tallized from thf/n-hexane giving a yellow, air-sensitive, crystalline
1
(203 MHz, CD2Cl2): δ = 42.7 (d, JRhP = 140.5 Hz) ppm. 103Rh
1
NMR (15.8 MHz, CD2Cl2): δ = 789 (d, JRhP = 140.5 Hz) ppm.
material. Yield: 68%, 48 mg, 0.07 mmol. M.p. 198 °C (dec.). [α]D22
=
ATR IR: ν = 3514 (w), 3220 (w), 2949 (w), 1630 (w), 1479 (w),
˜
1
–20.4 (c = 0.1, CH2Cl2). H NMR (400 MHz, CD2Cl2): δ = –0.06
1455 (w), 1439 (m), 1374 (w), 1281 (w), 1248 (m 1227 m), 1156 (m),
1103 (m), 1093 (m), 1071 (m), 1060 (m), 1032 (s), 1013 (m), 988
(m), 950 (m), 892 (w), 880 (w), 863 (w), 846 (w), 814 (w), 781 (m),
756 (s), 746 (s), 704 (s), 697 (s), 638 (s) cm–1.
C45H44F3NO4PRhS·(CH2Cl2)0.2 (902.76): calcd. C 60.14, H 4.96,
N 1.55; found C 60.27, H 5.06, N 1.53.
(dd, JHH = 14.9, JHH = 4.9 Hz, 1 H, CH2 ), 1.24 (s, 3 H, CH310),
2
3
3
9
2
7
1.29 (s, 3 H, CH3 ), 1.30 (d, JHH = 14.0 Hz, 1 H, CH2 ), 1.61 (dd,
3
3
2
2JHH = 14.0, JHH = 7.9 Hz, 1 H, CH2 ), 1.67 (d, JHH = 14.0 Hz,
7
3
3
1 H, CH2 ), 2.20 (t, JHH = 5.3 Hz, 1 H, CH4), 3.02 (d, JHH
=
7.9 Hz, 1 H, CH2), 3.06 (s, 3 H, OCH311), 3.49 (s, 1 H, NH), 4.96
3
3
(s, 1 H, CHbenzyl), 5.47 (d, JHH = 6.7 Hz, 1 H, CH6), 6.24 (d, JHH
3
3
1
= 8.83 Hz, 1 H, CHolefin), 6.43 (ddd, JHH = 6.7, JHH = 5.3, JRhH Methyl (2S3R)-3-[(tert-Butoxycarbonyl)amino]bicyclo[2.2.1]hept-5-
3
1
= 3.2 Hz, 1 H, CH5), 6.64 (dd, JHH = 9.1, JRhH = 3.3 Hz, 1 H,
ene-2-carboxylate (24): The compound was synthesized according
3
3
CHolefin), 7.34 (dd, JHH = 7.3, JHH = 1.5 Hz, 1 H, CHar), 7.40– to an established literature procedure by using tert-butyl alcohol; a
3
7.50 (m, 5 H, CHar), 7.67 (d, JHH = 8.2 Hz, 2 H, CHar) ppm.
colorless solid was obtained.[12] M.p. 44 °C. 1H NMR (700 MHz,
9
7
13C{1H} NMR (101 MHz, CD2Cl2): δ = 22.1 (s, 1 C, CH3 ), 23.9 (s,
CDCl3): δ = 1.38 (d, 2JHH = 8.9 Hz, 1 H, CH2 ), 1.44 (s, 9 H, CH3),
1 C, CH310), 24.4 (d, 3JRhC = 1.8 Hz, 1 C, CH2 ), 39.0 (s, 1 C, CH4),
1.51 (d, JHH = 9.2 Hz, 1 H, CH2 ), 3.08 (m, 1 H, CH4), 3.11 (m,
3
2
7
43.5 (s, 1 C, CH2 ), 43.6 (s, 1 C, C1), 50.0 (s, 1 C, OCH311), 68.9 (s,
1 H, CH1), 3.24 (dd, JHH = 9.0, JHH = 2.3 Hz, 1 H, CH2), 3.64
7
3
3
1
9
3
3
1 C, CHbenzyl), 69.4 (s, 1 C, CH2), 79.4 (d, JRhC = 6.4 Hz, 1 C,
(s, 3 H, OCH3 ), 4.61 (td, JHH = 10, JHH = 2.9 Hz, 1 H, CH3),
CHolefin), 79.8 (d, JRhC = 7.8 Hz, 1 C, CHolefin), 79.9 (s, 1 C, C8),
4.88 (d, JHH = 9.2 Hz, 1 H, NH), 6.20 (dd, JHH = 5.5, JHH =
1
3
3
3
1
1
98.7 (d, JRhC = 11.4 Hz, 1 C, CH5), 100.7 (d, JRhC = 6.4 Hz, 1 C, 3.0 Hz, 1 H, CH5), 6.46 (dd, 3JHH = 5.8, 3JHH = 3.1 Hz, 1 H, CH6)
1
CH6), 120.8 (q, JCF = 320.3 Hz, 1 C, CF3), 127.7 (s, 1 C, CHar),
128.6 (s, 1 C, CHar), 128.6 (s, 1 C, CHar), 128.9 (s, 1 C, CHar), 129.0
(s, 1 C, CHar), 129.7 (s, 1 C, CHar), 129.8 (s, 1 C, CHar), 131.3 (s, 1
C, CHar), 135.3 (d, 2JRhC = 2.3 Hz, 1 C, Cquart), 135.4 (s, 1 C, Cquart),
136.2 (s, 1 C, Cquart), 138.0 (d, 2JRhC = 1.8 Hz, 1 C, Cquart), 185.5 (d,
1JRhC = 63.5 Hz, 1 C, CO) ppm. 103Rh NMR (12.6 MHz, CD2Cl2): δ
ppm. 13C{1H} NMR (176 MHz, CDCl3): δ = 28.4 (s, 3 C, CH312),
7
46.4 (s, 1 C, CH1), 47.2 (s, 1 C, CH4), 47.6 (s, 1 C, CH2 ), 48.9 (s,
9
1 C, CH2), 51.5 (s, 1 C, OCH3 ), 53.8 (s, 1 C, CH3), 79.1 (s, 1 C,
C11), 133.0 (s, 1 C, CH5), 138.5 (s, 1 C, CH6), 155.5 (s, 1 C, C10),
173.2 (s, 1 C, C8) ppm. ATR IR: ν = 3409 (w, NH), 2978 (w), 2954
˜
(w), 2878 (w), 1709 (s, C=O), 1501 (s, C=C) 1449 m), 1437 (m),
1390 (m), 1356 (s), 1338 (m), 1300 (m), 1259 (m), 1240 (m), 1220
(m), 1207 (m), 1160 (s), 1120 (m), 1090 (m), 1072 (m), 1056 (s),
1031 (s), 1015 (m), 984 (m), 963 (m), 945 (m), 916 (m), 879 (m),
858 (m), 844 (m), 825 (m), 789 (m), 776 (m), 721 (m), 679 (m) cm–1.
C14H21NO4 (267.32): calcd. C 62.90, H 7.92, N 5.24; found C
62.63, H 8.06, N 5.24.
= –7569 (s) ppm. ATR IR: ν = 3234 (w, NH), 2961 (w, CH), 2882
˜
(w, CH), 2036 (m, CO), 1465 (w), 1389 (w), 1371 (w), 1326 (w), 1294
(m), 1283 (s), 1231 (s), 1218 (s), 1156 (s), 1103 (m), 1059 (m), 1023
(s), 992 (m), 953 (w), 895 (w), 880 (w), 864 (w), 847 (w), 817 (w),
778 (w), 752 (m), 743 (w), 706 (w), 689 (w), 666 (w), 633 (s), 609 (w)
cm–1. C28H29F3NO5RhS·thf0.2 (665.92): calcd. C 51.94, H 4.63, N
2.10; found C 52.02, H 4.67, N 2.09.
Methyl (2S3R)-3-(5H-Dibenzo[a,d]cyclohepten-5-ylamino)bicyclo-
[Rh(21)(PPh3)]OTf
0.07 mmol, 1 equiv.) was dissolved in thf (1 mL) under argon and
(23):
[Rh2(µ2-Cl)2(C2H4)4]
(26.2 mg, [2.2.1]hept-5-ene-2-carboxylate (25): Methyl 3-[(tert-butoxycarb-
onyl)amino]bicyclo[2.2.1]hept-5-ene-2-carboxylate (24) (270 mg,
5574
www.eurjic.org
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2009, 5561–5576

Chiral [Bis(olefin)amine]rhodium(I) Complexes
1.01 mmol, 1 equiv.) was dissolved in dcm (5 mL) and the solution
cooled to 0 °C. Trifluoroacetic acid (0.23 mL, 3.0 mmol, 3 equiv.)
was added dropwise and the reaction mixture stirred at room tem-
0.09 mmol, 2 equiv.) added. After 1 h, AgOTf (22.3 mg, 0.09 mmol,
2 equiv.) was added. The thf was removed under reduced pressure
and the residue dissolved in dcm (2 mL), filtered through Celite
perature for 4 h. The reaction was monitored by TLC. Water and the dcm removed under reduced pressure. The complex was
(5 mL) was added and the reaction mixture neutralized with
K2CO3 until no further CO2 was evolved. Next, the aqueous phase
was extracted five times with dcm (5 mL) and the organic phase
dried with powdered K2CO3. The solvent was removed under re-
duced pressure to yield the deprotected amine. The amine (110 mg,
0.66 mmol, 65%) was dissolved in dry dcm (5 mL) and triethyl-
amine (0.45 mL, 3.3 mmol, 5 equiv.) added. The solution was co-
oled with an ice bath, and tropCl (223 mg, 0.99 mmol, 1.5 equiv.)
was added. The reaction mixture was stirred for 6 h. The organic
phase was washed with aqueous sodium carbonate and the organic
phase dried with Na2SO4. The product was chromatographed on
silica gel (dcm/EtOH, 99:1). An oil was obtained, which solidified
to an off-white solid, still containing small amounts of residual
solvent after drying under high vacuum. Yield: 85%, 202 mg,
0.56 mmol. M.p. 127 °C. [α]2D2 = –25.3 (c = 0.1, CH2Cl2). endo/exo
= 1:2. endo conformer: 1H NMR (700 MHz, C6D6): δ = 0.80 (d,
recrystallized from thf/n-hexane to give a yellow, air-sensitive pow-
der. Yield: 64%, 36 mg, 0.06 mmol. M.p. 218–224 °C (dec.). [α]2D2
–50.1 (c = 0.1, CH2Cl2). 1H NMR (700 MHz, CD2Cl2): δ = 1.76
=
(d, 3JHH = 9.8 Hz, 1 H, CH2 ), 1.94 (d, 3JHH = 9.8 Hz, 1 H, CH2 ),
7
7
2.32 (s, 1 H, CH4), 3.13 (s, 1 H, CH1), 3.70 (dd, JHH = 8.5, JHH
= 3.05 Hz, 1 H, CH2), 3.92 (s, 3 H, OCH3), 4.03 (ddd, 3JHH = 8.5,
3JHH = 3.4, 3JHH = 1.2 Hz, 1 H, CH3), 4.94 (dd, 3JHH = 8.5, 2JRhH
= 2.1 Hz, 1 H, CHolefin), 4.99 (s, 1 H, NH), 5.07 (s, 1 H, CHbenzyl),
3
3
3
2
3
5.27 (dd, JHH = 8.7, JRhH = 2.6 Hz, 1 H, CHolefin), 6.34 (t, JHH
= 4.4 Hz, 1 H, CH6), 7.39 (td, JHH = 7.3, JHH = 1.3 Hz, 1 H,
3
4
CHar), 7.42 (td, JHH = 7.3, JHH = 1.5 Hz, 1 H, CHar), 7.35–7.50
(m, 4 H, CHar), 7.67 (m, 1 H, CHar), 7.69 (dd, 3JHH = 7.5, 1.07 Hz,
1 H, CHar), 7.76 (m, 1 H, CH5) ppm. 13C{1H} NMR (176 MHz,
CD2Cl2): δ = 46.2 (s, 1 C, CH1) 46.3 (s, 1 C, CH4), 51.0 (s, 1 C,
3
4
CH2), 53.2 (s, 1 C, CH7), 54.0 (d, JRhC = 14.2 Hz, 1 H, CHolefin),
1
54.9 (s, 1 C, OCH3), 58.5 (d, JRhC = 15.4 Hz, 1 C, CHolefin), 67.8
1
7
2
7
2JHH = 8.9 Hz, 1 H, CH2 ), 1.31 (d, JHH = 8.9 Hz, 1 H, CH2 ),
(s, 1 C, CHbenzyl), 69.0 (s, 1 C, CH3), 122.3 (s, 1 C, CH6), 124.9 (s,
1 C, CH5), 127.3 (s, 1 C, CHar), 128.2 (s, 1 C, CHar), 128.7 (s, 1 C,
CHar), 128.9 (s, 1 C, CHar), 129.1 (s, 1 C, CHar), 129.3 (s, 1 C,
2.42 (s, 1 H, NH), 2.66 (m, 1 H, CH1), 2.84 (s, 1 H, CH4), 2.87
3
3
9
(dd, JHH = 9.5, JHH = 3.4 Hz, 1 H, CH2), 3.37 (s, 3 H, OCH3 ),
3.37 (m, 1 H, CH3), 4.95 (s, 1 H, CHbenzyl), 6.05 (dd, JHH = 5.7, CHar), 129.4 (s, 1 C, CHar), 129.5 (s, 1 C, CHar), 134.9 (d, J =
3
3JHH = 2.9 Hz, 1 H, CH5), 6.61 (dd, JHH = 5.5, JHH = 2.8 Hz, 1
1.8 Hz, 1 C, Cquart), 136.3 (s, 1 C, Cquart), 136.8 (d, J = 1.8 Hz, 1
3
3
H, CH6), 6.94 (m, 2 H, CHolefin), 7.15–7.45 (m, 8 H, CHar) ppm. C, Cquart), 136.9 (d, J = 1.8 Hz, 1 C, Cquart), 181.0 (s, 1 C, Cquart),
13C{1H} NMR (176 MHz, C6D6): δ = 45.4 (s, 1 C, CH4), 46.4 (s, 184.0 (d, 1JRhC = 64.8 Hz, 1 C, CO) ppm. 103Rh NMR (22.1 MHz,
1 C, CH1), 46.8 (s, 1 C, CH2 ) 50.0 (s, 1 C, CH2), 50.5 (s, 1 C, CD Cl ): δ = –7348 (s) ppm. ATR IR: ν = 3125 (w, NH), 2957 (w,
7
˜
2
2
9
OCH3 ), 60.1 (s, 1 C, CH4), 68.99 (s, 1 C, CHbenzyl), 126.7 (s, 1 C, CH), 2052 (m, CO), 2038 (m, CO), 1645 (m, C=O), 1492 (w), 1448
CHar), 126.9 (s, 1 C, CHar), 128.3 (s, 1 C, CHar), 128.4 (s, 1 C, (m), 1385 (m), 1373 (m), 1327 (w), 1264 (s), 1222 (s), 1190 (m),
CHar), 129.4 (s, 1 C, CHar), 129.4 (s, 1 C, CHar), 130.0 (s, 1 C, 1151 (s), 1092 (m), 1077 (m), 1047 (m), 1028 (s), 960 (w), 927 (m),
CHar), 130.1 (s, 1 C, CHar), 130.3 (s, 1 C, CHar), 130.8 (s, 1 C, 910 (m), 893 (m), 868 (w), 841 (w), 831 (w), 814 (w), 778 (w), 770
CHar), 132.7 (s, 1 C, CH5), 134.0 (s, 1 C, Cquart), 134.1 (s, 1 C,
Cquart), 137.4 (s, 1 C, CH6), 140.4 (s, 1 C, Cquart), 141.1 (s, 1 C,
(m), 759 (s), 751 (w), 733 (m), 721 (m), 683 (w), 635 (s), 617 (m),
605 (m) cm–1. C26H23F3NO6RhS·(C4H8O)0.4 (666.27): calcd. C
Cquart), 172.4 (s, 1 C, C8) ppm. exo conformer: 1H NMR (700 MHz, 49.75, H 3.96, N 2.10; found C 49.83, H 3.99, N 2.09.
2
7
2
C6D6): δ = 0.77 (d, JHH = 8.5 Hz, 1 H, CH2 ), 1.29 (d, JHH
=
7
3
[Rh(25)(PPh3)]OTf
(27):
[Rh2(µ2-Cl)2(C2H4)4]
(27.2 mg,
8.5 Hz, 1 H, CH2 ), 2.57 (d, JHH = 11.9 Hz, 1 H, NH), 2.84 (m,
1 H, CH1), 2.89 (m, 1 H, CH4), 3.07 (dd, JHH = 9.5, JHH
=
3
3
0.07 mmol, 1 equiv.) was dissolved in thf (1 mL) under argon and
25 (50 mg, 0.14 mmol, 2 equiv.) added. After 1 h, PPh3 (36.7 mg,
0.14 mmol, 2 equiv.) was added. The reaction mixture was stirred
for an additional 1 h before AgOTf (40 mg, 0.15, 2.2 equiv.) was
added. The solvent was removed under reduced pressure and the
residue dissolved in dcm (2 mL), filtered through Celite and the
solvent removed under reduced pressure. Recrystallization from
dcm/n-hexane gave the desired complex. Yield: 52%, 64 mg,
0.07 mmol, not optimized. M.p. Ͼ230 °C (dec.). [α]2D2 = –2.1 (c =
0.1, CH2Cl2). 1H NMR (400 MHz, CD2Cl2): δ = 1.35 (d, J =
3.4 Hz, 1 H, CH2), 3.50 (s, 3 H, OCH3 ), 3.82 (ddd, JHH = 12.0,
3JHH = 9.5, 3JHH = 3.5 Hz, 1 H, CH3), 4.45 (s, 1 H, CHbenzyl), 6.07
9
3
3
3
3
(dd, JHH = 5.5, JHH = 3.1 Hz, 1 H, CH5), 6.64 (dd, JHH = 5.5,
3JHH = 3.1 Hz, 1 H, CH6), 7.14 (m, 2 H, CHolefin), 7.10–7.45 (m,
6, CHar), 7.97 (d, JHH = 7.9 Hz, 1 H, CHar), 8.07 (d, JHH
=
3
3
7.9 Hz, 1 H, CHar) ppm. 13C{1H} NMR (176 MHz, C6D6): δ =
46.0 (s, 1 C, CH4), 46.2 (s, 1 C, CH1) 47.5 (s, 1 C, CH2 ), 49.5 (s,
7
1 C, CH2), 50.7 (s, 1 C, OCH3 ), 58.8 (s, 1 C, CHbenzyl), 60.4 (s, 1
9
C, CH3), 122.5 (s, 1 C, CHar), 123.1 (s, 1 C, CHar), 125.6 (s, 1 C,
CHolefin), 125.7 (s, 1 C, CHar), 127.7 (s, 1 C, CHar), 128.1 (s, 1 C,
CHar), 128.8 (s, 1 C, CHar), 128.9 (s, 1 C, CHar), 131.1 (s, 1 C,
CHolefin), 131.2 (s, 1 C, CHar), 132.4 (s, 1 C, CH5), 134.1 (s, 1 C,
Cquart), 134.1 (s, 1 C, Cquart), 138.5 (s, 1 C, CH6), 140.4 (s, 1 C,
7
7
9.4 Hz, 1 H, CH2 ), 1.69 (d, J = 9.8 Hz, 1 H, CH2 ), 2.79 (m, 1 H,
NH), 3.15 (s, 3 H, OCH3), 3.24 (dd, J = 8.5, 3.5 Hz, 1 H, CH2),
3.26 (s, 1 H, CH1), 3.44 (ddd, J = 12.5, 9.0, 3.2 Hz, 1 H, CH3),
3.59 (s, 1 H, CH4), 3.67 (ddd, J = 8.4, 4.0, 1.7 Hz, 1 H, CHolefin),
4.09 (ddd, J = 8.3, 4.0, 2.0 Hz, 1 H) 5.06 (d, J = 6.70 Hz, 1 H,
CHolefin), 6.37 (dd, J = 5.48, 2.74 Hz, 1 H, CH5), 6.43 (dd, J =
5.78, 2.43 Hz, 1 H, CH6), 7.35–7.65 (m, 17 H, CHar), 7.70–7.80 (m,
6 H, CHar) ppm. 13C{1H} NMR (101 MHz, CD2Cl2): δ = 45.2 (d,
Cquart), 141.1 (s, 1 C, Cquart), 173.1 (s, 1 C, C8) ppm. ATR IR: ν =
˜
2967 (w), 2945 (w), 1723 (s), 1597 (w), 1562 (w), 1482 (w), 1467
(w), 1450 (m), 1433 (m), 1364 (m), 1340 (m), 1298 (w), 1248 (m),
1192 (m), 1172 (m), 1155 (m), 1130 (w), 1113 (m), 1067 (w), 1037
(w), 963 (m), 935 (w), 913 (w), 897 (w), 887 (w), 862 (w), 846 (w),
835 (w), 816 (w), 794 (m), 777 (m), 762 (s), 749 (s), 734 (s), 714
(m), 702 (s), 674 (m), 635 (m), 610 (m) cm–1. HRMS (MALDI, 3-
HPA): found (calcd.) for [C24H23O2N + H]+ 358.1798 (358.1802).
C24H23NO2 (357.44): calcd. C 80.64, H 6.49, N 3.92; found C
80.75, H 6.38, N 3.81.
J = 1.8 Hz, 1 C, CH4), 45.5 (s, 1 C, CH1), 46.3 (s, 1 C, CH2 ), 50.0
7
(s, 1 C, CH2), 55.6 (s, 1 C, OCH3), 58.3 (d, J = 16.9 Hz, 1 C,
CHolefin), 60.4 (d, J = 18.0 Hz, 1 C, CHolefin), 60.3 (s, 1 C, CH3),
66.0 (s, 1 C, CHbenzyl), 127.9 (s, 1 C, CHar), 128.1 (s, 1 C, CHar),
2
129.3 (d, JPC = 10.1 Hz, 6 C, CHar), 129.5 (s, 1 C, CHar), 129.7
1
(d, JPC = 29.2 Hz, 3 C, Cquart), 129.7 (s, 1 C, CHar), 130.0 (s, 1 C,
4
CHar), 130.1 (s, 2 C, CHar), 130.1 (s, 1 C, CHar), 131.6 (d, JPC
=
[Rh(25)(CO)]OTf (26): [Rh2(µ2-Cl)2(CO)4] (16.8 mg, 0.04 mmol, 2.3 Hz, 3 C, CHar), 133.0 (s, 1 C, CH5), 133.6 (s, 1 C, Cquart), 134.4
1 equiv.) was dissolved in thf (1 mL) under argon and 25 (31 mg,
3
(d, JPC = 11.4 Hz, 6 C, CHar), 136.2 (s, 1 C, Cquart), 138.4 (d, J =
Eur. J. Inorg. Chem. 2009, 5561–5576
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
5575

T. Zweifel, D. Scheschkewitz, T. Ott, M. Vogt, H. Grützmacher
FULL PAPER
1.8 Hz, 1 C, Cquart), 139.7 (d, J = 2.3 Hz, 1 C, Cquart), 141.0 (s, 1
[3] T. Zweifel, J. V. Naubron, T. Büttner, T. Ott, H. Grützmacher,
Angew. Chem. 2008, 120, 3289–3293; Angew. Chem. Int. Ed.
2008, 47, 3245–3249.
C, CH6), 182.1 (s, 1 C, Cquart) ppm. 31P{1H} NMR (162 MHz,
1
CD2Cl2): δ = 45.5 (d, JRhP = 162.5 Hz) ppm. 103Rh NMR
[4] T. Zweifel, J. V. Naubron, H. Grützmacher, Angew. Chem.
2009, 121, 567–571; Angew. Chem. Int. Ed. 2009, 48, 559–563.
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38, 621–624.
1
(12.6 MHz, CD2Cl2): δ = –7472 (d, JRhP = 162.5 Hz) ppm. ATR
IR: ν = 3125 (m), 1977 (w), 1629 (m), 1573 (w), 1473 (w), 1453
˜
(w), 1436 (m), 1356 (m), 1301 (m), 1282 (m), 1249 (m), 1224 (m),
1183 (w), 1142 (m), 1094 (m), 1058 (m), 1028 (m), 999 (m), 935
(w), 915 (m), 897 (w), 867 (w), 842 (w), 827 (w), 810 (w), 776 (w),
769 (m), 761 (m), 747 (m), 726 (m), 707 (m), 697 (m), 635 (s), 607
(m) cm–1. C43H38F3NO5PRhS·(CH2Cl2)0.3 (897.19): calcd. C 57.97,
H 4.34, N 1.56; found C 58.29, H 4.40, N 1.56.
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29, 946–948; b) A. S. Bloss, P. R. Brook, R. M. Ellam, J. Chem.
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[Rh(15-H)(PPh3)] (28): [Rh(15)(PPh3)]OTf (16) (50 mg, 6 µm,
1 equiv.) was suspended in thf (2 mL) and treated with KOtBu
(6.8 mg, 6 µm, 1 equiv.). A color change from green to red was
observed. The solution was stirred further for 30 min. The solvent
was removed under reduced pressure, the resulting oil dissolved in
toluene and filtered through Celite. Addition of n-hexane precipi-
tated part of the product, which was analyzed by NMR spec-
troscopy. Yield: 50%, 25 mg 3 µm. 31P NMR indicates that the
product contains 10% of an unknown impurity. 1H NMR
[8] a) A. J. Birch, J. Chem. Soc. 1946, 593–597; b) G. M. Rubot-
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4579; Angew. Chem. Int. Ed. 2008, 47, 4482–4502.
5
(500 MHz, C6D6): δ = 1.01 (m, 2 H, CH2 ), 1.19 (m, 1 H, CH1),
2
6
1.24 (m, 2 H, CH2 ), 2.20 (m, 2 H, CH2 ), 4.45 (m, 2 H, CH2allyl),
6.03 (s, 1 H, CHbenzyl), 6.48 (d, 3JHH = 7.34 Hz, 2 H, CHolefin), 6.82
(s, 1 H, NH), 6.95–7.16 (m, 17 H, CHar), 7.26–7.38 (m, 9 H, CHar
and CH4) ppm. 13C{1H} NMR (126 MHz, C6D6): δ = 22.5 (s, 1 C,
[11] A. Srikrishna, G. V. R. Sharma, S. Danieldoss, P. Hemamalini,
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to the trop moiety in all structures.
CH2 ), 24.3 (s, 1 C, CH2 ), 28.9 (s, 1 C, CH2 ), 30.1 (s, 1 C, CH1),
5
2
6
7
59.8 (m, 1 C, CH2 ), 71.9 (s, 1 C, CHbenzyl), 122–145 (30 C, CHar
and Cquart), 127.5 (s, 2 C, CHolefin), 148.5 (s, 1 C, CH4), 166.6 (s, 1
C, CH3) ppm. 31P{1H} NMR (283 MHz, CD2Cl2): δ = 40.8 (d,
1JRhP = 155.3 Hz) ppm. 1H, 103Rh NMR (15.8 MHz, CD2Cl2): δ =
1
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Acknowledgments
This work was supported by the Swiss National Science Founda-
tion (SNF) and the ETH Zürich. We thank Dr. I. Atodiresei, Dr.
T. Rantanen and Prof. Dr. C. Bolm for the generous donation of a
sample of methyl (2S3R)-3-[(tert-butoxycarbonyl)amino]bicyclo-
[2.2.1]hept-5-ene-2-carboxylate.
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Published Online: November 13, 2009
5576
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Eur. J. Inorg. Chem. 2009, 5561–5576