Synthesis of highly substituted unsymmetrical 1,2-diamines, 1,2-diimines, imidazolium salts and imidazolylidenes by aldimine cross-coupling

Article abstract of DOI:10.1055/s-2006-950237

α-Aminonitriles derived from aromatic aldehydes and primary amines can be deprotonated quantitatively without the use of protecting groups. The 1,2-addition of the resulting stabilized α-aminocarbanions to imines yields α-aminoimines and the tautomeric enediamines. These unstable compounds can directly be oxidized to 1,2-diimines or reduced to 1,2-diamines in a one-pot reaction. 1,2-Diamines can be obtained in high diastereoselectivity by reduction of the 1,2-diimines. In this case, the relative configuration of the products can be chosen depending on the reduction conditions. Cyclization of the unsymmetrical diimines with halomethyl ethers or esters leads to 1,3,4,5-tetrasubstituted imidazolium salts which can serve as starting materials for the preparation of highly substituted nucleophilic carbenes. Georg Thieme Verlag Stuttgart.

Full text of DOI:10.1055/s-2006-950237

PAPER
3727
Synthesis of Highly Substituted Unsymmetrical 1,2-Diamines, 1,2-Diimines,
Imidazolium Salts and Imidazolylidenes by Aldimine Cross-Coupling
S
ynthesis of 1,2-
o
iamines, 1,
r
a
es, Imidazo
l
lium
S
i
alts an
e
Imidazolylidene
K
s
ison, Till Opatz*
Johannes Gutenberg-Universität Mainz, Duesbergweg 10-14, 55128 Mainz, Germany
Fax +49(6131)3924786; E-mail: opatz@uni-mainz.de
Received 19 May 2006; revised 3 July 2006
though the explosion risk associated with various nitr-
Abstract: a-Aminonitriles derived from aromatic aldehydes and
primary amines can be deprotonated quantitatively without the use
of protecting groups. The 1,2-addition of the resulting stabilized a-
aminocarbanions to imines yields a-aminoimines and the tautomer-
onates and the lack of availability of functionalized
nitroalkanes are drawbacks of the procedure. A straight-
forward approach for the synthesis of 1,2-diamines is the
ic enediamines. These unstable compounds can directly be oxidized reaction of imines with a-aminocarbanions which yields
to 1,2-diimines or reduced to 1,2-diamines in a one-pot reaction.
1,2-diamines in a single step. This C–C-bond-forming
1,2-Diamines can be obtained in high diastereoselectivity by reduc-
process also allows the preparation of unsymmetrical
tion of the 1,2-diimines. In this case, the relative configuration of
products without the risk of the formation of regioiso-
the products can be chosen depending on the reduction conditions.
mers.24 On the other hand, the preparation of a-amino-
Cyclization of the unsymmetrical diimines with halomethyl ethers
carbanions may be cumbersome and the use of an N-
protecting group is required unless products with one ter-
tiary amino function are desired. A convenient method for
the generation of stabilized a-aminocarbanions is the
deprotonation of Strecker products. Unlike the cyanohy-
drins, which can not be deprotonated quantitatively with-
out decomposition, N-monosubstituted and N-
unsubstituted a-aminonitriles derived from aromatic alde-
hydes can be converted to the corresponding anions upon
treatment with a suitable base such as potassium hexa-
methyldisilazide (KHMDS). The resulting carbanions
have been employed for the preparation of highly substi-
tuted pyrrolidines.25–27 Here, we report on a simple one-
pot procedure for the preparation of unsymmetrical
1,2,N,N¢-tetrasubstituted 1,2-diamines from a-aminoni-
triles.28,29
or esters leads to 1,3,4,5-tetrasubstituted imidazolium salts which
can serve as starting materials for the preparation of highly substi-
tuted nucleophilic carbenes.
Key words: cross-coupling, carbenes, 1,2-diamines, nitrogen het-
erocycles, reduction
The 1,2-diamine moiety is the common key element of a
variety of compounds that are currently in the focus of in-
terest in various areas of chemical and pharmaceutical re-
search.1 The applications of 1,2-diamines range from
ligands of antitumor-active platinum complexes having
improved properties compared to the cytostatic cisplatin
[cis-diaminedichloroplatinum(II)]2 to asymmetric synthe-
sis. Chiral 1,2-diamines can serve as auxiliaries or as
ligands used for asymmetric additions to carbonyl com-
pounds,3,4 aldol5 and Diels–Alder reactions,6–8 the asym-
metric ring opening of epoxides,9,10 dihydroxylations6,11,12
and many more. In addition, many pharmaceuticals and
some natural products with the 1,2-diamine function such
as the ajmaline alkaloids,13 the dragmacidins,14 some
eudistomins15 or biotin (vitamin H) are known. In view of
the broad range of possible applications for substituted
1,2-diamines, the development of simple methods for
their preparation from readily available starting materials
remains a rewarding task. Frequently utilized approaches
for the synthesis of 1,2-diamines are diamination and ami-
nohydroxylation reactions of olefins,16–18 the conversion
of diols to diazides,19 the opening of epoxides with azide20
or the reductive dimerization of imines.21,22 However,
most of the known methods are limited to compounds
with a specific pattern of substitution or lead to symmetri-
cal products only. The aza-Henry reaction,23 i.e. the addi-
tion of nitronates to imines, is a simple method for the
preparation of 1,2-di- or 1,2-N-trisubstituted diamines, al-
To investigate the reactivity of deprotonated Strecker
products towards electrophilic imines, the potassium salt
of (benzhydrylamino)phenylacetonitrile (1a) was reacted
with N-(benzylidene)benzenesulfonamide (2) in THF at
–78 °C, yielding a diastereomeric mixture of the addition
products 3 (67%, anti/syn = 2:1) (Scheme 1). The relative
configuration of the major diastereomer could be assigned
by X-ray crystallographic analysis.30
It turned out that the presence of a sulfonyl group or a sim-
ilar strongly electron-withdrawing N-substituent in the
electrophile is no requirement for the C–C-bond forma-
1) KHMDS,
THF,
–78 °C
CN
NHSO2Ph
2)
SO2Ph
N
N
H
H
CN
N
1a
2
3
SYNTHESIS 2006, No. 21, pp 3727–3738
Advanced online publication: 09.10.2006
x
x.
x
x
.
2
0
0
6
67%, anti/syn = 2:1
DOI: 10.1055/s-2006-950237; Art ID: T08206SS
© Georg Thieme Verlag Stuttgart · New York
Scheme 1 Addition of an aminonitrile to an imine.

3728
C. Kison, T. Opatz
PAPER
tion. However, the addition of deprotonated aminonitriles son to this symmetrical aldimine coupling reaction, the
1 to benzalanilines 4 at –50 °C takes a different course. If 1,2-addition of deprotonated a-aminonitriles to imines
the basicity of the intermediate amide ion is sufficiently permits the selective cross-coupling of two different C–N-
high, an intramolecular transprotonation followed by the fragments. Whereas the crossed benzoin reaction requires
elimination of cyanide, i.e. a retro-Strecker reaction, takes protection of the cyanohydrin, no protecting group is nec-
place. The resulting unstable a-aminonimines 5 or the tau- essary for the analogous aldimine cross-coupling. The re-
tomeric enediamines 631 can either be oxidized to di- sults of the aerial oxidation to diimines 7 are summarized
imines 7 with molecular oxygen32 or reduced with sodium in Table 1. Reduction of the intermediates 5 and 6 to the
cyanoborohydride to form diamines 8 in a one-pot se- 1,2-diamines 8 was initially carried out by addition of so-
quence (see Scheme 2).
dium cyanoborohydride and acetic acid to the reaction
mixture (Table 2).
As in the preparation of the 1,2-diimines, the products
were obtained in moderate to good yields although the
diastereoselectivity was poor in most cases. To assign the
relative configuration of the diastereomers, formaldehyde
aminals of the diamines 8a and 8m were prepared and ex-
amined by NOE experiments.36 In addition, characteristic
1H and 13C chemical shifts of the products were compared
to NMR data of vicinal diamines reported in the litera-
ture.37–41 In accordance with a chelate model for the tran-
sition state, the anti products were predominantly formed.
N
N
·
CN
KHMDS
R2
NH
R1
THF
R2
N
R1
R2
NH
R1
1
R4
R3
N
4
R1
R1
N
H
R2
R3
NH
R2
R3
1,2-Diamines can be prepared with a higher degree of dia-
stereoselectivity by the reduction of the purified diimines
7 with borane-THF. Additives like sodium borohydride or
phthalic acid turned out to have a dramatic effect on the
rate and the outcome of the reduction. When catalytic
amounts of sodium borohydride were used as the additive,
the syn diamines were formed preferentially, whereas the
addition of phthalic acid42 led to the preponderant forma-
tion of the anti-configured products (Table 3). In both cas-
es, the reduction proceeded in quantitative yield.
R1
N
N
R4
R2
– CN
NH
R4
NH
R4
R3
CN
6
5
NaCNBH3
AcOH, EtOH
air
R1
N
R1 NH R3
R2 HN R4
syn-8
N
R4
R1 NH R3
R2 HN R4
anti-8
Apart from their use as precursors for the preparation of
1,2-diamines, 1,2-diimines 7 can be readily converted to
imidazolium salts 9 upon treatment with chloromethyl es-
ters or ethers according to protocols by Glorius43 (Method
A) and Arduengo44 (Method B), respectively (Table 4).
As these compounds carry no substituent in the 2-posi-
tion, they can serve as starting materials for the synthesis
of unsymmetrical 1,3,4,5-tetrasubsituted imidzolylidenes:
Imidazolium salt 9b could be deprotonated with tert-bu-
tyllithium to give carbene 10, which was converted in situ
to the stable thione 11 upon oxidation with elemental sul-
R2
R3
7
Scheme 2 Mechanism of the diamine synthesis.
The course of the 1,2-addition closely resembles the aza-
analogue of the benzoin condensation, where catalytic
amounts of cyanide are used to generate low concentra-
tions of a-aminocarbanions from imines.32–35 In compari-
Table 1 1,2-Diimines via Aerial Oxidation
Nitrile
1a
R1
R2
Imine
4a
R3
R4
Product
7a
Yield (%)a
Ph2CH
Ph2CH
Ph2CH
Ph(CH2)2
Me
Ph
4-ClC6H4
4-ClC6H4
Ph
Ph
65
69
67
62
55
73
65
1a
Ph
4b
4e
4-MeC6H4
4-ClC6H4
4-MeC6H4
4-ClC6H4
4-ClC6H4
Ph
7b
1a
Ph
7c
1b
Ph
4b
4e
4-ClC6H4
Ph
7d
1c
2-naphthyl
2-naphthyl
Ph
7e
1c
Me
4f
1-naphthyl
4-ClC6H4
7f
1a
Ph2CH
4a
7a
a Yield after purification by preparative TLC.
Synthesis 2006, No. 21, 3727–3738 © Thieme Stuttgart · New York

PAPER
Synthesis of 1,2-Diamines, 1,2-Diimines, Imidazolium Salts and Imidazolylidenes
3729
Table 2 1,2-Diamines via Reduction by Sodium Cyanoborohydride
Nitrile
1a
R1
R2
Imine
4a
4b
4c
R3
R4
Product
8a
Yielda (%) dr (anti/syn)
Ph2CH
Ph2CH
Ph2CH
Ph2CH
Ph2CH
Ph(CH2)2
Ph(CH2)2
Ph(CH2)2
Ph(CH2)2
Me
Ph
4-ClC6H4
4-ClC6H4
Ph
Ph
63
64
34
41
68
60
55
59
42
60
55
58
55
35
37
33
1.2:1
1.3:1
1.2:1
1.2:1
1.7:1
1.7:1
1.6:1
1.7:1
2.3:1
2.4:1
1.6:1
1.5:1
3.2:1
2:1
1a
Ph
4-MeC6H4
4-MeC6H4
Ph
8b
8c
1a
Ph
1a
Ph
4d
4e
4-pyridyl
Ph
8d
8e
1a
Ph
4-ClC6H4
Ph
1b
1b
1b
1b
1c
Ph
4a
4b
4e
4-ClC6H4
4-ClC6H4
Ph
8f
Ph
4-MeC6H4
4-ClC6H4
4-ClC6H4
Ph
8g
Ph
8h
8i
Ph
4f
1-naphthyl
4-ClC6H4
4-ClC6H4
Ph
2-naphthyl
2-naphthyl
2-naphthyl
2-naphthyl
Ph
4a
4b
4e
8j
1c
Me
4-MeC6H4
4-ClC6H4
4-ClC6H4
Ph
8k
8l
1c
Me
1c
Me
4f
1-naphthyl
4-ClC6H4
4-ClC6H4
Ph
8m
8n
8o
1d
1d
1d
i-Pr
4a
4b
4e
i-Pr
Ph
4-MeC6H4
4-ClC6H4
1.4:1
1.6:1
i-Pr
Ph
8p
a Yield after purification by preparative TLC.
Table 3 Diastereoselective Reduction of 1,2-Diimines
Table 4 Synthesis of Imidazolium Salts
R1
R2
R1
N
R3
N
R1
N
R3
N
Method A
N
Method B
Method A or B
BH3·THF
BH3·THF
X
R2
R4
R2
R4
N
R4
R3
cat. NaBH4
phthalic acid
(1 equiv)
7
7
9
R1 NH
R2
R3
R1 NH
R2
R3
Method A: PivOCH2Cl/AgOTf, X = OTf
Method B: MeOCH2Cl or EtOCH2Cl, X = Cl
HN R4
HN R4
Diimine
7a
Product
9a
Method
Yield (%)a
syn-8
anti-8
B
A
B
B
B
65
21
72
76
85b
Diimine
7a
Product
Method
dr (anti/syn)
1:5.5
1:20
7b
9b
8a
8b
8e
8l
A
A
A
A
A
B
B
B
7c
9c
7b
7d
9d
7c
1:6
7f
9e
a Yield after purification by flash column chromatography.
b The pure imidazolium chloride was transformed to the less hygro-
scopic tetraphenylborate salt before characterization.
7e
1:11
7f
8m
8a
8b
8e
3:10
7a
27:1
fur in quantitative yield (Scheme 3). N-Heterocyclic car-
benes of this type are currently receiving considerable
attention as tunable ligands for catalytically active metal
complexes or as organocatalysts which promote a variety
of C–C- and C–X-bond-forming processes.45–48
7b
9:1
7c
3.5:1
Synthesis 2006, No. 21, 3727–3738 © Thieme Stuttgart · New York

3730
C. Kison, T. Opatz
PAPER
preparative TLC was performed on PSC glass plates (silica gel 60
F
254, 2 mm, 20 × 20 cm, Macherey-Nagel). Flash column chroma-
Cl
Cl
tography was carried out on silica gel (32–63 mm, 60 Å, MP Bio-
medicals GmbH).
tBuLi
N
N
N
N
N-[2-(Benzhydrylamino)-2-cyano-1,2-diphenylethyl]benzene-
sulfonamide (3)
To a stirred solution of the aminonitrile 1a (400.0 mg, 1.34 mmol)
in anhyd THF (20 mL), was added a solution of KHMDS (294.2
mg, 1.47 mmol) in anhyd THF (5 mL) at –78 °C over a period of
1 min under argon. After 10 min, a solution of N-benzylideneben-
zenesulfonamide (345.3 mg, 1.41 mmol) in anhyd THF (5 mL) was
slowly added. The solution was stirred another 20 min at –78 °C,
then the reaction was quenched by the addition of sat. aq NaHCO3.
The mixture was partitioned between EtOAc and H2O, the organic
layer was washed with brine, dried (Na2SO4) and the solvent was re-
moved in vacuo to give a colorless oil (902.2 mg). The crude prod-
uct was purified by flash chromatography (SiO2, tert-butyl methyl
ether–petroleum ether, 3:1) and crystallized from EtOAc–petro-
leum ether to remove the remaining N-benzylidenebenzenesulfona-
mide, to afford sulfonamide 3 (combined yield: 489.7 mg, 67%) as
colorless crystals. Ratio of anti/syn isomers = 2:1; mp 141 °C (anti),
152 °C (syn); Rf 0.24 (anti), 0.33 (syn) (cyclohexane–EtOAc, 4:1).
Cl
9a
10
Cl
N
N
S8
S
IR (KBr): 3257 (s, NH), 3063 (m), 3030 (m), 2230 (vw, C≡N), 1494
11
quantitative
(s), 1450 (s), 1333 (s), 1168 (s), 1089 (s), 608 (s) cm–1.
1H NMR (300 MHz, CDCl3): d = 7.57 (pseudo-d, Japp = 7.4 Hz, 2 H,
syn), 7.46 (pseudo-d, Japp = 7.0 Hz, 2 H, anti), 7.37–6.80 (m, 44 H),
6.56 (pseudo-d, Japp = 7.4 Hz, 2 H, syn), 5.68 (d, J = 10.5 Hz, 1 H,
N1H syn), 5.25 (d, J = 8.6 Hz, 1 H, N1H anti), 4.80 (d, J = 7.5 Hz, 1
H, Ph2CH syn), 4.74 (d, J = 8.6 Hz, 1 H, 1-H anti), 4.65 (d, J = 10.5
Hz, 1 H, 1-H syn), 4.61 (d, J = 7.9 Hz, 1 H, Ph2CH anti), 3.63 (d,
J = 7.5 Hz, 1 H, N2H syn), 2.31 (d, J = 7.9 Hz, 1 H, N2H anti).
Scheme 3 Formation of N-heterocyclic carbenes.
In conclusion, we have described a simple access to high-
ly substituted unsymmetrical 1,2-diamines and 1,2-di-
imines by aldimine cross-coupling. The reaction can be
performed in one pot and does not require protecting-
group operations. Compared to the one-pot reduction pro-
13C NMR (75.5 MHz, CDCl3): d = 143.2 (syn), 143.1 (anti), 142.9
(syn), 142.2 (anti), 139.6 (anti), 139.3 (syn), 134.5 (anti), 134.2 (an-
cedure, reduction of the purified 1,2-diimines with bo- ti), 134.1 (syn), 133.8 (syn), 132.7 (syn), 132.3 (anti), 129.4 (anti),
129.2 (anti), 129.0–126.3 (partly overlapping signals), 118.5 (C≡N
syn), 118.1 (C≡N anti), 69.3 (C2 syn), 68.1 (C2 anti), 67.3 (C1 syn),
66.3 (C1 anti), 62.6 (Ph2CH syn), 62.1 (Ph2CH anti).
rane-THF furnishes 1,2-diamines with significantly
higher diastereoselectivity. Furthermore, the relative con-
figuration of the reduction products can be directed de-
pending on the reduction conditions. Cyclization of the
1,2-diimines with chloromethyl ethers or esters leads to
highly substituted imidazolium salts, which can serve as
precursors of structurally diverse N-heterocyclic car-
benes.
ESI-MS: m/z = 166.96 [Ph2CH]+, 517.23 [M – CN]+, 539.23 [M –
HCN + Na]+.
Anal. Calcd for C34H29N3O2S: C, 75.11; H, 5.38; N, 7.73. Found: C,
75.24; H, 5.52; N, 7.71.
Diimines 7a–f; General Procedure (Table 1)
To a stirred solution of the aminonitrile 1 (1.70 mmol) in anhyd
THF (1.5 mL), was added a solution of KHMDS (373.0 mg, 1.87
mmol) in anhyd THF (2 mL) at –50 °C under argon. After 3 min, a
solution of the imine 4 (1.70 mmol) in anhyd THF (1 mL) was add-
ed and the mixture was allowed to warm up to –20 °C within 100
min. The argon atmosphere was replaced by air and the solution was
allowed to warm up to r.t. After extraction with EtOAc, the organic
layer was washed with brine, dried (Na2SO4) and the solvent was re-
moved in vacuo.
1H NMR and 13C NMR spectra were recorded on a Bruker AC-300
or AMX-400 spectrometer, chemical shifts were referenced to the
residual solvent signal (CDCl3: dH = 7.24 ppm, dC = 77.0 ppm). FD-
MS spectra were measured on a Finnigan MAT-95 spectrometer.
ESI-HRMS spectra were measured on a Waters Q-TOF-Ultima 3
equipped with a LockSpray interface (HCO2Na or NaI/CsI as exter-
nal reference). IR spectra were recorded on a PerkinElmer 1760X
FTIR spectrometer. The melting points were measured on Dr. Tot-
toli apparatus (Büchi) and are uncorrected. a-Aminonitriles 1a–d
were synthesized via Strecker-reaction according to known proce-
dures.27,49–51 Imines 4a–f were prepared by condensation of alde-
hydes and amines in CH2Cl2 in the presence of Na2SO4 and catalytic
amounts of AcOH. Their analytical data matched those reported in
the literature.52–57 N-Benzylidenebenzenesulfonamide was synthe-
sized from benzenesulfonamide and benzaldehyde dimethyl ace-
tal.58 THF was freshly distilled from potassium/benzophenone
under argon. All other solvents and reagents were purchased from
commercial suppliers and were used without further purification.
Petroleum ether had a boiling range of 40–70 °C. TLC was per-
formed on aluminum sheets coated with silica gel (60 F254, Merck),
N-[2-(Benzhydrylimino)-1-(4-chlorophenyl)-2-phenyleth-
ylidene]aniline (7a)
Prepared from aminonitrile 1a and imine 4a according to the gener-
al method; yellow oil (681.3 mg). A portion (185.6 mg) of the crude
product was purified by preparative TLC (SiO2, toluene–EtOAc,
100:1) to give diimine 7a (144.3 mg, 65%) as a yellow solid; mp
135 °C; Rf 0.67 (toluene–EtOAc, 100:1).
IR (film): 3062 (w), 3027 (w), 1615 (s), 1588 (s), 1490 (s), 1092
(m), 694 (s) cm–1.
Synthesis 2006, No. 21, 3727–3738 © Thieme Stuttgart · New York

PAPER
Synthesis of 1,2-Diamines, 1,2-Diimines, Imidazolium Salts and Imidazolylidenes
3731
1H NMR (300 MHz, CDCl3): d = 7.83–7.76 (m, 2 H), 7.57 (pseudo-
d, Japp = 8.5 Hz, 2 H), 7.37–7.05 (m, 15 H), 6.84–6.78 (m, 3 H),
6.59–6.52 (m, 2 H), 5.53 (s, 1 H, Ph2CH).
13C NMR (75.5 MHz, CDCl3): d = 163.8 (N=C–C=N), 163.1
(N=C–C=N), 148.9, 143.7, 143.3, 137.5, 137.2, 134.4, 130.7,
129.9–126.2 (partly overlapping signals), 124.7, 119.8 (2 C,
aniline-C2,6), 71.2 (Ph2CH).
N-[1-(4-Chlorophenyl)-2-(2-phenylethylimino)-2-phenyleth-
ylidene]-4-methylaniline (7d)
Prepared from aminonitrile 1b and imine 4b according to the gen-
eral method, orange oil (670.9 mg). A portion (201.4 mg) of the
crude product was purified by preparative TLC (SiO2, toluene–
EtOAc, 40:1) to give diimine 7d (127.6 mg, 62%) as a yellow solid;
mp 88 °C; Rf 0.59 (toluene–EtOAc, 40:1).
IR (film): 3025 (m), 2360 (m), 1618 (s), 1589 (s), 1504 (s), 1092 (s),
699 (s) cm–1.
1H NMR (300 MHz, CDCl3): d = 7.71–6.90 (m, 14 H), 6.94 (pseu-
do-d, Japp = 8.3 Hz, 2 H, aniline-3,5-H), 6.72 (pseudo-d, Japp = 8.3
Hz, 2 H, aniline-2,6-H), 3.58–3.37 (m, 2 H, NCH2), 2.99–2.72 (m,
2 H, CH2Ph), 2.22 (s, 3 H, CH3).
13C NMR (75.5 MHz, CDCl3): d = 164.6, 163.4, 146.8, 140.1,
137.2, 136.9, 134.9, 134.6, 130.6, 130.0–128.0 (partly overlapping
signals), 127.5, 126.1, 119.8, 56.6 (NCH2), 37.1 (PhCH2), 20.9
(CH3).
FD-MS: m/z (%) = 436.2 (100, [M]+), 437.2 (33), 438.3 (39), 439.3
(10), 440.3 (2).
ESI-HRMS: m/z [M + H]+ calcd for C29H25ClN2: 437.1784; found:
437.1767.
FD-MS: m/z (%) = 484.4 (100, [M]+), 485.4 (41), 486.4 (32), 487.4
(16).
ESI-HRMS: m/z [M + H]+ calcd for C33H25ClN2: 485.1784; found:
485.1766.
Anal. Calcd for C33H25ClN2: C, 81.72; H, 5.20; N, 5.78. Found: C,
81.59; H, 5.24; N, 5.75.
N-[2-(Benzhydrylimino)-1-(4-chlorophenyl)-2-phenyleth-
ylidene]-4-methylaniline (7b)
Prepared from aminonitrile 1a and imine 4b according to the gener-
al method; yellow oil (823.7 mg). A portion (175.3 mg) of the crude
product was purified by preparative TLC (SiO2, cyclohexane–
EtOAc, 10:1 + 1% EtNMe2) to give diimine 7b (122.3 mg, 69%) as
a yellow solid; mp 146 °C; Rf 0.70 (cyclohexane–EtOAc, 10:1 + 1%
EtNMe2).
Anal. Calcd for C29H25ClN2: C, 79.71; H, 5.77; N, 6.41. Found: C,
79.65; H, 5.68; N, 6.45.
IR (film): 3061 (m), 3025 (m), 1615 (s), 1588 (s), 1504 (s), 1492 (s),
1092 (m), 699 (s) cm–1.
1H NMR (300 MHz, CDCl3): d = 7.86–7.01 (m, 19 H), 6.67–6.50
(m, 4 H, aniline-3,5-H, aniline-2,6-H), 5.50 (s, 1 H, Ph2CH), 2.10
(s, 3 H, CH3).
13C NMR (75.5 MHz, CDCl3): d = 163.3 (N=C–C=N), 163.0
(N=C–C=N), 146.3 (aniline-C1), 143.7, 143.4, 137.2, 137.1, 134.7,
134.6, 130.7, 129.9–125.4 (partly overlapping signals), 120.2 (2 C,
aniline-C2,6), 71.2 (Ph2CH), 20.7 (CH3).
FD-MS: m/z (%) = 498.2 (100, [M]+), 499.3 (34), 500.3 (39), 501.2
(13).
ESI-HRMS: m/z [M + H]+ calcd for C34H27ClN2: 499.1941; found:
499.1923.
N-[2-(Methylimino)-2-(2-naphthyl)-1-phenylethylidene]-4-
chloroaniline (7e)
Prepared from aminonitrile 1c and imine 4e according to the general
method; orange oil (672.6 mg). A portion (196.8 mg) of the crude
product was purified by preparative TLC (SiO2, cyclohexane–tert-
butyl methyl ether, 2:1) to give diimine 7e (104.1 mg, 55%) as a yel-
low solid; mp 122–125 °C; Rf 0.55 (cyclohexane–tert-butyl methyl
ether, 2:1).
IR (film): 3058 (m), 2925 (m), 2364 (m), 1616 (s), 1577 (m), 1480
(s), 1090 (m), 754 (s), 691 (s) cm–1.
1H NMR (300 MHz, CDCl3): d = 8.05–7.66 (m, 7 H), 7.55–7.38 (m,
5 H), 7.06 (pseudo-d, Japp = 8.6 Hz, 2 H, aniline-3,5-H), 6.76 (pseu-
do-d, Japp = 8.6 Hz, 2 H, aniline-2,6-H), 3.32 (s, 3 H, CH3).
13C NMR (75.5 MHz, CDCl3): d = 166.2 (2 C, N=C–C=N), 148.3
(aniline-C1), 135.7, 134.5, 134.4, 132.9, 131.9, 131.8, 130.2,
129.7–125.7 (partly overlapping signals), 123.4, 120.8, 42.5 (CH3).
FD-MS: m/z (%) = 382.3 (100, [M]+), 383.3 (26), 384.3 (27), 385.3
(7).
ESI-HRMS: m/z [M + H]+ calcd for C25H19ClN2: 383.1315; found:
383.1300.
Anal. Calcd for C34H27ClN2: C, 81.83; H, 5.45; N, 5.61. Found: C,
81.83; H, 5.54; N, 5.65.
N-[2-(Benzhydrylimino)-1,2-diphenylethylidene]-4-chloro-
aniline (7c)
Prepared from aminonitrile 1a and imine 4e according to the gener-
al method; yellow oil (833.6 mg). A portion (145.2 mg) of the crude
product was purified by preparative TLC (SiO2, toluene–EtOAc,
40:1) to give diimine 7c (95.9 mg, 67%) as a pale yellow solid; mp
139 °C; Rf 0.45 (cyclohexane–EtOAc, 10:1 + 1% EtNMe2).
Anal. Calcd for C25H19ClN2: C, 78.42; H, 5.00; N, 7.32. Found: C,
78.32; H, 5.01; N, 7.32.
IR (film): 3062 (m), 3027 (m), 1626 (s), 1492 (m), 1480 (m), 1089
(m), 694 (s) cm–1.
1H NMR (300 MHz, CDCl3): d = 7.84–7.01 (m, 20 H), 6.71 (pseu-
do-d, Japp = 8.6 Hz, 2 H, aniline-3,5-H), 6.42 (pseudo-d, Japp = 8.6
Hz, 2 H, aniline-2,6-H), 5.54 (s, 1 H, Ph2CH).
13C NMR (75.5 MHz, CDCl3): d = 165.9 (N=C–C=N), 163.0
(N=C–C=N), 147.7 (aniline-C1), 143.6, 143.4, 137.3, 135.8, 131.6,
130.7, 129.9, 129.4, 128.7–125.5 (partly overlapping signals),
121.2 (2 C, aniline-C2,6), 71.3 (Ph2CH).
N-[2-(Methylimino)-1-(1-naphthyl)-2-(2-naphthyl)ethylidene]-
4-chloroaniline (7f)
Prepared from aminonitrile 1c and imine 4f according to the general
method; yellow solid (656.6 mg). A portion (176.3 mg) of the crude
product was purified by preparative TLC (SiO2, toluene–EtOAc,
10:1) to give diimine 7f (130.4 mg, 73%) as a yellow resin; Rf 0.57
(toluene–EtOAc, 10:1).
IR (film): 3058 (w), 2360 (m), 1592 (s), 1482 (m), 1092 (m), 803
(m), 776 (s) cm–1.
1H NMR (300 MHz, CDCl3): d = 8.13–7.30 (m, 14 H), 7.10 (pseu-
do-d, Japp = 8.6 Hz, 2 H), 6.85 (pseudo-d, Japp = 8.6 Hz, 2 H), 3.36
(s, 3 H, CH3).
13C NMR, DEPT (75.5 MHz, CDCl3): d = 167.4 (N=C–C=N),
166.3 (N=C–C=N), 148.3, 134.8, 134.7, 134.4, 132.9, 132.5, 132.3,
FD-MS: m/z (%) = 485.0 (100, [M + H]+), 486.0 (37), 487.0 (38),
488.0 (11).
ESI-HRMS: m/z [M + H]+ calcd for C33H25ClN2: 485.1784; found:
485.1794.
Anal. Calcd for C33H25ClN2: C, 81.83; H, 5.45; N, 5.61. Found: C,
81.75; H, 5.15; N, 6.00.
Synthesis 2006, No. 21, 3727–3738 © Thieme Stuttgart · New York

3732
C. Kison, T. Opatz
PAPER
132.2, 130.4–126.9 (partly overlapping signals), 126.6, 126.4,
125.9, 124.9, 123.6, 120.7, 42.5 (CH3).
13C NMR (75.5 MHz, CDCl3): d = 147.5 (aniline-C1 syn), 146.8
(aniline-C1 anti), 144.1 (2 C), 142.9, 142.3, 139.8 (2 C), 139.1,
138.3, 133.0 (ClC6H4-C4 anti), 132.7 (ClC6H4-C4 syn), 129.3–
126.9 (partly overlapping signals), 117.8 (aniline-C4 syn), 117.4
(aniline-C4 anti), 113.9 (2 C, aniline-C2,6 syn), 113.5 (2 C, aniline-
C2,6 anti), 65.7 (C2 syn), 64.4 (C2 anti), 63.6 (C1 syn), 63.6
(Ph2CH anti), 63.4 (Ph2CH syn), 62.2 (C1 anti).
FD-MS: m/z (%) = 265.2 (4, [NaphCH=NC6H4Cl]+), 267.2 (2),
432.3 (100, [M]+), 433.3 (28), 434.3 (32), 435.3 (7).
ESI-HRMS: m/z [M + H]+ calcd for C29H21ClN2: 433.1469; found:
433.1486.
FD-MS: m/z (%) = 216.4 (51, [ClC6H4CH=NHPh]+), 217.4 (5),
218.4 (12), 272.6 (100, [Ph2CHNH=CHPh]+), 273.6 (18), 489.1
(62, [M + H]+), 490.1 (50), 491.1 (30), 492.1 (13).
ESI-HRMS: m/z [M + H]+ calcd for C33H29ClN2: 489.2097; found:
489.2076.
Anal. Calcd for C29H21ClN2: C, 80.45; H, 4.89; N, 6.47. Found: C,
80.54; H, 4.82; N, 6.36.
Diamines 8a–q; General Procedures
Via One-Pot Synthesis (Table 2)
Method 1: To a stirred solution of the aminonitrile 1 (1.70 mmol) in
anhyd THF (1.5 mL), was added a solution of KHMDS (373 mg,
1.87 mmol) in anhyd THF (2 mL) at –50 °C under argon. After
3 min, a solution of the imine 4 (1.70 mmol) in anhyd THF (1 mL)
was added and the mixture was allowed to warm up to –20 °C with-
in 100 min. Solid NaBH3CN (427 mg, 6.8 mmol) was added to the
solution, followed by a mixture of AcOH (0.6 mL, 10.5 mmol) and
EtOH (6.4 mL, 109 mmol). The mixture was stirred overnight at r.t.
After addition of EtOAc (40 mL) and phase separation, the organic
layer was washed several times with aq 1 N NaOH and finally with
brine, dried (Na2SO4) and the solvent was removed in vacuo.
Anal. Calcd for C33H29ClN2: C, 81.05; H, 5.98; N, 5.73. Found: C,
80.91; H, 5.81; N, 5.66.
N2-Benzhydryl-1-(4-chlorophenyl)-N1-(4-methylphenyl)-2-
phenylethane-1,2-diamine (8b)
Following the general Method 1, a yellow oil (835.9 mg) was ob-
tained from aminonitrile 1a and imine 4b. A portion (157.7 mg) of
the crude product was purified by preparative TLC (SiO2, cyclohex-
ane–EtOAc, 10:1 + 1% EtNMe2) to give diamine 8b (108.6 mg,
64%) as a slightly reddish solid; ratio of anti/syn isomers = 1.3:1.
Reduction of the diimine 7b according to Methods 2A and 2B led
to diamine 8b in quantitative yield. No further purification was re-
quired; ratio of anti/syn isomers = 1:20 (Method 2A), anti/syn = 9:1
(Method 2B); Rf 0.70 (cyclohexane–EtOAc, 10:1 + 1% EtNMe2).
Via Reduction of the Diimines (Table 3)
Method 2A: To a stirred solution of the diimine 7 (0.50 mmol) in an-
hyd THF (4 mL) was added solid NaBH4 (9.5 mg, 0.25 mmol) under
argon and the mixture was cooled to 0 °C. A fresh solution of bo-
rane-THF (0.75 mL, 1 M in THF) was added and stirring was con-
tinued for 30 min at 0 °C and for a further 15 h at r.t. After addition
of ethanolamine (0.5 mL), the mixture was stirred for 3–18 h and
partitioned between EtOAc and H2O. The organic layer was washed
with H2O, dried (Na2SO4) and the solvent was removed in vacuo.
IR (film): 3405 (m, NH), 3347 (m, NH), 3060 (m), 3026 (m), 1616
(m), 1519 (s), 1490 (s), 1090 (m), 700 (s) cm–1.
1H NMR (300 MHz, CDCl3), COSY, HMQC, HMBC (400 MHz,
CDCl3): d = 7.34–6.56 (m, 42 H), 6.40 (pseudo-d, Japp = 8.5 Hz, 2
H, aniline-2,6-H syn), 6.31 (pseudo-d, Japp = 8.5 Hz, 2 H, aniline-
2,6-H anti), 4.58 (s, 1 H, Ph2CH anti), 4.56 (s, 1 H, Ph2CH syn), 4.45
(d, J = 5.3 Hz, 1 H, 1-H anti), 4.30 (d, J = 7.5 Hz, 1 H, 1-H syn),
3.88 (d, J = 5.3 Hz, 1 H, 2-H anti), 3.63 (d, J = 7.5 Hz, 1 H, 2-H
syn), 2.17 (s, 3 H, CH3 syn), 2.15 (s, 3 H, CH3 anti).
13C NMR, DEPT (75.5 MHz, CDCl3), HMQC, HMBC (100.6 MHz,
CDCl3): d = 145.2 (aniline-C1 syn), 144.5 (aniline-C1 anti), 144.1
(2 C), 142.9, 142.4, 140.0, 139.9, 139.2, 138.6, 132.8, 132.6, 129.5–
126.6 (partly overlapping signals), 114.0 (2 C, aniline-C2,6 syn),
113.6 (2 C, aniline-C2,6 anti), 65.6 (C2 syn), 64.4 (C2 anti), 63.9
(C1 syn), 63.5 (Ph2CH anti), 63.4 (Ph2CH syn), 62.5 (C1 anti), 20.3
(2 C, CH3).
Method 2B: A stirred solution of the diimine 7 (0.50 mmol) and
phthalic acid (166 mg, 1 mmol) in anhyd THF (4 mL) was cooled
to –20 °C under argon. After addition of a borane-THF solution
(1 mL, 1 M in THF), the mixture was gradually warmed to r.t. and
stirring was maintained for a further 15 h. The work-up procedure
and the isolation of the product were performed as described for
Method 2A.
N2-Benzhydryl-1-(4-chlorophenyl)-N1-phenyl-2-phenylethane-
1,2-diamine (8a)
Method 1: Following the general Method 1, a light yellow oil (767.0
mg) was obtained from aminonitrile 1a and imine 4a. A portion
(117.7 mg) of the crude product was purified by preparative TLC
(SiO2, cyclohexane–EtOAc, 10:1 + 1% EtNMe2) to give diamine
8a (79.6 mg, 63%) as a colorless solid; ratio of anti/syn
isomers = 1.2:1.
FD-MS: m/z (%) = 230.4 (16, [ClC6H4CH=NHTol]+), 231.4 (2),
232.4 (7), 272.5 (42, [Ph2CHNH=CHPh]+), 273.5 (9), 503.0 (100,
[M]+), 504.0 (44), 505.0 (37), 506.0 (10).
ESI-HRMS: m/z [M + H]+ calcd for C34H31ClN2: 503.2254; found:
503.2246.
Method 2: Reduction of the diimine 7a according to Methods 2A
and 2B led to diamine 8a in quantitative yield. No further purifica-
tion was required; ratio of anti/syn isomers = 1:5.5 (Method 2A),
27:1 (Method 2B); Rf 0.50 (cyclohexane–EtOAc, 10:1 + 1%
EtNMe2).
N2-Benzhydryl-N1-(4-methylphenyl)-1,2-diphenylethane-1,2-
diamine (8c)
Following the general Method 1, a yellow oil (760.1 mg) was ob-
tained from aminonitrile 1a and imine 4c. A portion (143.7 mg) of
the crude product was purified by preparative TLC (SiO2, toluene–
CH2Cl2, 20:1) to give diamine 8c (32.2 mg, 34%) as a reddish solid;
ratio of anti/syn isomers = 1.2:1; Rf 0.60 (toluene–CH2Cl2, 20:1).
IR (film): 3409 (m, NH), 3352 (m, NH), 3061 (m), 3025 (m), 1603
(s), 1503 (s), 1491 (s), 1090 (m), 748 (s), 699 (s) cm–1.
1H NMR (300 MHz, CDCl3), COSY (400 MHz, CDCl3): d = 7.34–
6.93 (m, 42 H), 6.69–6.57 (m, 2 H, aniline-4-H), 6.48 (pseudo-d,
Japp = 7.7 Hz, 2 H, aniline-2,6-H syn), 6.37 (pseudo-d, Japp = 7.5 Hz,
2 H, aniline-2,6-H anti), 5.30 (br s, 1 H, N1H syn), 4.77 (br s, 1 H,
N1H anti), 4.59 (s, 1 H, Ph2CH anti), 4.57 (s, 1 H, Ph2CH syn), 4.47
(d, J = 5.3 Hz, 1 H, 1-H anti), 4.34 (d, J = 7.4 Hz, 1 H, 1-H syn),
3.91 (d, J = 5.3 Hz, 1 H, 2-H anti), 3.65 (d, J = 7.4 Hz, 1 H, 2-H
syn).
IR (film): 3412 (m, NH), 3061 (m), 3026 (m), 1618 (m), 1520 (s),
1493 (m), 745 (m), 700 (s) cm–1.
1H NMR (300 MHz, CDCl3): d = 7.34–6.91 (m, 40 H), 6.86 (pseu-
do-d, Japp = 8.5 Hz, 2 H, aniline-3,5-H syn,), 6.82 (pseudo-d,
Japp = 8.5 Hz, 2 H, aniline-3,5-H anti), 6.43 (pseudo-d, Japp = 8.5
Hz, 2 H, aniline-2,6-H syn), 6.40 (pseudo-d, Japp = 8.5 Hz, 2 H,
aniline-2,6-H anti), 4.56 (s, 2 H, Ph2CH), 4.49 (d, J = 5.5 Hz, 1 H,
1-H anti), 4.36 (d, J = 6.8 Hz, 1 H, 1-H syn), 3.89 (d, J = 5.5 Hz, 1
Synthesis 2006, No. 21, 3727–3738 © Thieme Stuttgart · New York

PAPER
Synthesis of 1,2-Diamines, 1,2-Diimines, Imidazolium Salts and Imidazolylidenes
3733
H, 2-H anti), 3.72 (d, J = 6.8 Hz, 1 H, 2-H syn), 2.16 (s, 3 H, CH3
syn), 2.14 (s, 3 H, CH3 anti).
Japp = 8.6 Hz, 2 H, aniline-2,6-H anti), 5.28 (br s, 1 H, N1H), 4.81
(br s, 1 H, N1H), 4.57 (s, 2 H, Ph2CH), 4.44 (d, J = 5.2 Hz, 1 H, 1-
H anti), 4.33 (d, J = 6.6 Hz, 1 H, 1-H syn), 3.91 (d, J = 5.2 Hz, 1 H,
2-H anti), 3.72 (d, J = 6.6 Hz, 1 H, 2-H syn).
13C NMR (75.5 MHz, CDCl3): d = 145.5 (aniline-C1 syn), 144.8
(aniline-C1 anti), 144.3, 144.2, 143.0, 142.4, 141.3, 140.3, 140.0,
139.6, 129.5–126.7 (partly overlapping signals), 126.5, 126.3,
113.9 (2 C, aniline-C2,6 syn), 113.6 (2 C, aniline-C2,6 anti), 65.6
(C2 syn), 64.6 (C2 anti), 64.4 (C1 syn), 63.4 (Ph2CH anti), 63.3
(Ph2CH syn), 63.1 (C1 anti), 20.3 (2 C, CH3).
FD-MS: m/z (%) = 196.4 (12, [PhCH=NHTol]+), 272.5 (19,
[Ph2CHNH=CHPh]+), 469.1 (100, [M + H]+), 470.0 (76), 471.1
(19).
13C NMR (75.5 MHz, CDCl3): d = 146.3 (aniline-C1 syn), 145.6
(aniline-C1 anti), 144.1 (2 C), 142.9, 142.3, 140.6, 140.0, 139.3,
139.1, 129.1–126.1 (partly overlapping signals), 122.0 (aniline-C4
syn), 121.7 (aniline-C4 anti), 114.9 (2 C, aniline-C2,6 syn), 114.6 (2
C, aniline-C2,6 anti), 65.5 (C2 syn), 64.4 (C2 anti), 64.1 (C1 syn),
63.5 (Ph2CH anti), 63.3 (Ph2CH syn), 62.8 (C1 anti).
FD-MS: m/z (%) = 216.3 (27, [PhCH=NHC6H4Cl]+), 217.4 (3),
218.4 (10), 272.5 (100, [Ph2CHNH=CHPh]+), 489.0 (94, [M]+),
490.0 (72), 491.0 (44), 492.0 (20).
ESI-HRMS: m/z [M + H]+ calcd for C34H32N2: 469.2643; found:
469.2634.
ESI-HRMS: m/z [M + H]+ calcd for C33H29ClN2: 489.2097; found:
489.2075.
N2-Benzhydryl-N1,2-diphenyl-1-(4-pyridyl)ethane-1,2-diamine
(8d)
Anal. Calcd for C33H29ClN2: C, 81.05; H, 5.98; N, 5.73. Found: C,
80.96; H, 5.86; N, 5.76.
Following the general Method 1, an orange solid (810.8 mg) was
obtained from aminonitrile 1a and imine 4d. A portion (359.4 mg)
of the crude product was purified by flash column chromatography
(SiO2, toluene–CH2Cl2, 20:1) to give diamine 8d (138.0 mg, 41%)
as a yellow solid; ratio of anti/syn isomers = 1.2:1; Rf 0.51 (toluene–
EtOAc, 1:1).
1-(4-Chlorophenyl)-N1,2-diphenyl-N2-(2-phenethyl)ethane-1,2-
diamine (8f)
Following the general Method 1, a yellow oil (741.0 mg) was ob-
tained from aminonitrile 1b and imine 4a. A portion (183.6 mg) of
the crude product was purified by preparative TLC (SiO2, toluene–
EtOAc, 20:1) to give diamine 8f (107.1 mg, 60%) as a yellow oil;
ratio of anti/syn isomers = 1.7:1; Rf 0.39 (toluene–EtOAc, 20:1).
IR (film): 3405 (s, NH), 3027 (m), 1601 (s), 1502 (s), 1028 (m), 748
(s), 699 (s) cm–1.
1H NMR (300 MHz, CDCl3), COSY, HMQC, HMBC (400 MHz,
CDCl3): d = 8.45 (pseudo-d, Japp = 5.9 Hz, 2 H, pyridine-2,6-H an-
ti), 8.35 (pseudo-d, Japp = 5.5 Hz, 2 H, pyridine-2,6-H syn), 7.37–
6.94 (m, 38 H), 6.69 (pseudo-t, Japp = 7.4 Hz, 1 H, aniline-4-H syn),
6.64 (pseudo-t, Japp = 7.4 Hz, 1 H, aniline-4-H anti), 6.49 (pseudo-
d, Japp = 7.8 Hz, 2 H, aniline-2,6-H syn), 6.40 (pseudo-d, Japp = 8.6
Hz, 2 H, aniline-2,6-H anti), 5.38 (br s, 1 H, N1H syn), 4.79 (br s, 1
H, N1H anti), 4.63 (s, 1 H, Ph2CH anti), 4.59 (s, 1 H, Ph2CH syn),
4.52 (mc, 1 H, 1-H anti), 4.35 (d, J = 7.6 Hz,1 H, 1-H syn), 3.98 (d,
J = 5.1 Hz, 1 H, 2-H anti), 3.66 (d, J = 7.6 Hz, 1 H, 2-H syn).
13C NMR (75.5 MHz, CDCl3), HMQC, HMBC (100.6 MHz,
CDCl3): d = 150.7 (pyridine-C4), 149.6 (2 C, pyridine-C2,6), 149.5
(2 C, pyridine-C2,6), 149.4 (pyridine-C4), 147.2, 146.4, 143.8 (2
C), 142.7, 142.1, 139.3, 138.5, 129.1, 128.9–126.2 (partly overlap-
ping signals), 123.1 (2 C, pyridine-C3,5), 122.5 (2 C, pyridine-
C3,5), 118.1 (aniline-C4), 117.8 (aniline-C4), 113.9 (2 C, aniline-
C2,6), 113.4 (2 C, aniline-C2,6), 65.3 (C2 syn), 64.0 (C2 anti), 63.7
(C1 syn), 63.5 (Ph2CH anti), 63.4 (Ph2CH syn), 62.0 (C1 anti).
IR (film): 3397 (s, NH), 3026 (m), 1603 (s), 1503 (s), 1090 (m), 750
(s), 699 (s) cm–1.
1H NMR (300 MHz, CDCl3): d = 7.31–6.76 (m, 32 H), 6.68–652
(m, 2 H, aniline-4-H), 6.41–6.35 (m, 4 H, aniline-2,6-H), 5.25 (br s,
1 H, N1H), 4.85 (br s, 1 H, N1H), 4.46 (d, J = 4.9 Hz, 1 H, 1-H anti),
4.22 (d, J = 7.0 Hz, 1 H, 1-H syn), 4.02 (d, J = 4.9 Hz, 1 H, 2-H an-
ti), 3.73 (d, J = 7.0 Hz, 1 H, 2-H syn), 2.87–2.51 (m, 8 H,
CH2CH2Ph), 1.48 (br s, 1 H, N2H).
13C NMR, DEPT (75.5 MHz, CDCl3): d = 147.5 (aniline-C1 syn),
146.8 (aniline-C1 anti), 140.3, 140.0, 139.8, 139.7, 139.3, 138.0,
132.9 (ClC6H4-C4 anti), 132.6 (ClC6H4-C4 syn), 129.2–126.2 (part-
ly overlapping signals), 117.4 (2 C, aniline-C4), 113.8 (2 C, aniline-
C2,6 syn), 113.6 (2 C, aniline-C2,6 anti), 68.6 (C2 syn), 67.1 (C2
anti), 63.4 (C1 syn), 62.0 (C1 anti), 48.2 (2 C, NHCH2), 36.2
(PhCH2 anti), 36.1 (PhCH2 syn).
FD-MS: m/z (%) = 210.4 (44, [PhC2H4NH=CHPh]+), 211.4 (7),
216.4 (10, [ClC6H4CH=NHPh]+), 217.4 (2), 218.4 (4), 426.8 (100,
[M]+), 427.8 (71), 428.8 (43), 429.8 (21).
ESI-HRMS: m/z [M + H]+ calcd for C28H27ClN2: 427.1941; found:
427.1940.
FD-MS: m/z (%) = 183.3 (41, [PyrCH=NHPh]+), 184.3 (26), 272.5
(100, [Ph2CHNH=CHPh]+), 273.5 (18), 455.9 (73, [M + H]+), 456.9
(67), 457.9 (17).
ESI-HRMS: m/z [M + H]+ calcd for C32H29N3: 456.2439; found:
456.2420.
Anal. Calcd for C28H27ClN2: C, 78.76; H, 6.37; N, 6.56. Found: C,
78.66; H, 6.49; N, 6.41.
N2-Benzhydryl-N1-(4-chlorophenyl)-1,2-diphenylethane-1,2-di-
amine (8e)
1-(4-Chlorophenyl)-N1-(4-methylphenyl)-N2-(2-phenethyl)-2-
phenylethane-1,2-diamine (8g)
Following the general Method 1, an orange oil (761.3 mg) was ob-
tained from aminonitrile 1b and imine 4b. A portion (162.2 mg) of
the crude product was purified by preparative TLC (SiO2, toluene–
EtOAc, 40:1) to give diamine 8g (86.1 mg, 55%) as a reddish oil;
ratio of anti/syn isomers = 1.6:1; Rf 0.31 (toluene–EtOAc, 40:1).
Following the general Method 1, a yellow oil (833.2 mg) was ob-
tained from aminonitrile 1a and imine 4e. A portion (137.1 mg) of
the crude product was purified by preparative TLC (SiO2, cyclohex-
ane–EtOAc, 10:1 + 1% EtNMe2) to give diamine 8e (91.7 mg, 68%)
as a colorless solid; ratio of anti/syn isomers = 1.7:1. Reduction of
the diimine 7c according to Methods 2A and 2B led to diamine 8e
in quantitative yield. No further purification was required; ratio of
anti/syn isomers = 1:6 (Method 2A), 3.5:1 (Method 2B); Rf 0.45
(cyclohexane–EtOAc, 10:1 + 1% EtNMe2).
IR (film): 3400 (m, NH), 3061 (w), 3026 (m), 1616 (m), 1520 (s),
1489 (m), 1090 (m), 700 (s) cm–1.
1H NMR (300 MHz, CDCl3), COSY, HMQC, HMBC (400 MHz,
CDCl3): d = 7.35–6.88 (m, 28 H), 6.87–6.82 (m, 4 H, aniline-3,5-
H), 6.33–6.28 (m, 4 H, aniline-2,6-H), 4.44 (d, J = 5.1 Hz, 1 H, 1-
H anti), 4.19 (d, J = 7.1 Hz, 1 H, 1-H syn), 4.00 (d, J = 5.1 Hz, 1 H,
2-H anti), 3.72 (d, J = 7.1 Hz, 1 H, 2-H syn), 2.89–2.49 (m, 8 H,
HNCH2CH2Ph), 2.15 (s, 6 H, CH3).
IR (film): 3411 (m, NH), 3062 (m), 3026 (m), 1618 (m), 1519 (s),
1496 (s), 700 (s) cm–1.
1H NMR (300 MHz, CDCl3): d = 7.33–6.90 (m, 44 H), 6.39 (pseu-
do-d, Japp = 8.6 Hz, 2 H, aniline-2,6-H syn), 6.32 (pseudo-d,
Synthesis 2006, No. 21, 3727–3738 © Thieme Stuttgart · New York

3734
C. Kison, T. Opatz
PAPER
13C NMR (75.5 MHz, CDCl3), HMQC, HMBC (100.6 MHz,
CDCl3): d = 145.2 (aniline-C1 syn), 144.5 (aniline-C1 anti), 140.3,
140.1, 139.8, 139.7, 139.3, 138.2, 132.8 (ClC6H4-C4 anti), 132.5
(ClC6H4-C4 syn), 129.5 (4 C, aniline-C3,5), 129.0 (4 C), 128.6 (4
C), 128.4–127.2 (partly overlapping signals), 126.6, 126.1, 113.8 (2
C, aniline-C2,6 syn), 113.7 (2 C, aniline-C2,6 anti), 68.6 (C2 syn),
67.1 (C2 anti), 63.6 (C1 syn), 62.2 (C1 anti), 48.2 (2 C, NHCH2),
36.2 (PhCH2 anti), 36.0 (PhCH2 syn), 20.3 (2 C, CH3).
65.7 (C2 syn), 59.2 (C1 syn), 57.4 (C1 anti), 48.3 (NHCH2 anti),
48.2 (NHCH2 syn), 36.1 (PhCH2 anti), 35.8 (PhCH2 syn).
FD-MS: m/z (%) = 210.4 (100, [PhC2H4NH=CHPh]+), 211.4 (10),
266.5 (72, [NaphCH=NHC6H4Cl]+), 267.5 (15), 268.5 (19), 477.0
(99, [M + H]+), 478.0 (59), 479.0 (38), 480.0 (15).
ESI-HRMS: m/z [M + H]+ calcd for C32H29ClN2: 477.2097; found:
477.2118.
FD-MS: m/z (%) = 210.4 (37, [PhC2H4NH=CHPh]+), 211.4 (5),
230.4 (14, [ClC6H4CH=NHTol]+), 231.4 (3), 232.4 (4), 441.0 (100,
[M + H]+), 442.0 (38), 443.0 (38), 444.0 (12).
ESI-HRMS: m/z [M + H]+ calcd for C29H29ClN2: 441.2097; found:
441.2093.
Anal. Calcd for C32H29ClN2: C, 80.57; H, 6.13; N, 5.87. Found: C,
80.45; H, 6.16; N, 5.69.
1-(4-Chlorophenyl)-N1-phenyl-N2-methyl-2-(2-naphth-
yl)ethane-1,2-diamine (8j)
Following the general Method 1, an orange oil (680.9 mg) was ob-
tained from aminonitrile 1c and imine 4a. A portion (185.6 mg) of
the crude product was purified by preparative TLC (SiO2, EtOAc–
toluene, 2:1) to give diamine 8j (106.6 mg, 60%) as a red oil; ratio
of anti/syn isomers = 2.4:1; Rf 0.30, 0.45 (EtOAc–toluene, 2:1).
Anal. Calcd for C29H29ClN2: C, 78.98; H, 6.63; N, 6.35. Found: C,
78.92; H, 6.46; N, 6.36.
N1-(4-Chlorophenyl)-N2-(2-phenethyl)-1,2-diphenylethane-1,2-
diamine (8h)
Following the general Method 1, a yellow oil (798.6 mg) was ob-
tained from aminonitrile 1b and imine 4e. A portion (130.6 mg) of
the crude product was purified by preparative TLC (SiO2, toluene–
EtOAc, 20:1) to give diamine 8h (68.7 mg, 59%) as a yellow oil; ra-
tio of anti/syn isomers = 1.7:1; Rf 0.53 (toluene–EtOAc, 20:1).
IR (film): 3409 (s, NH), 3051 (w), 3024 (w), 1602 (s), 1503 (s),
1487 (m), 1091 (m), 751 (s), 692 (m) cm–1.
1H NMR (300 MHz, CDCl3): d = 8.00–6.84 (m, 26 H), 6.67–6.66
(m, 2 H, aniline-4-H), 6.50–6.38 (m, 4 H, aniline-2,6-H), 4.86 (br s,
1 H, N1H), 4.62 (d, J = 5.1 Hz, 1 H, 1-H anti), 4.44 (d, J = 7.0 Hz,
1 H, 1-H syn), 4.08 (d, J = 5.1 Hz, 1 H, 2-H anti), 3.84 (d, J = 7.0
Hz, 1 H, 2-H syn), 2.31 (s, 3 H, CH3 anti), 2.27 (s, 3 H, CH3 syn).
13C NMR, DEPT (75.5 MHz, CDCl3): d = 147.4 (aniline-C1 syn),
146.9 (aniline-C1 anti), 140.0, 138.3, 137.4, 136.5, 133.2, 133.1,
133.1, 133.0, 132.6, 129.4–124.4 (partly overlapping signals),
117.6 (2 C, aniline-C4), 113.8 (2 C, aniline-C2,6 syn), 113.7 (2 C,
aniline-C2,6 anti), 70.9 (C2 syn), 69.7 (C2 anti), 63.2 (C1 syn), 61.9
(C1 anti), 34.5 (CH3 syn), 34.4 (CH3 anti).
IR (film): 3392 (m, NH), 3062 (w), 3026 (w), 1519 (s), 1496 (s),
1091 (m), 700 (s) cm–1.
1H NMR (300 MHz, CDCl3): d = 7.30–7.02 (m, 34 H), 6.31 (pseu-
do-d, Japp = 8.8 Hz, 4 H, aniline-2,6-H), 5.29 (br s, 1 H, N1H), 4.94
(br s, 1 H, N1H), 4.44 (mc, 1 H, 1-H anti), 4.22 (d, J = 6.6 Hz, 1 H,
1-H syn), 4.06 (d, J = 5.0 Hz, 1 H, 2-H anti), 3.81 (d, J = 6.6 Hz, 1
H, 2-H syn), 2.83–2.56 (m, 8 H, HNCH2CH2Ph).
13C NMR, DEPT (75.5 MHz, CDCl3): d = 146.3 (aniline-C1 syn),
145.7 (aniline-C1 anti), 140.9, 140.5, 139.9, 139.8, 139.4, 138.7,
129.4–126.5 (partly overlapping signals), 126.1, 121.7 (2 C,
aniline-C4), 114.7 (4 C, aniline-C2,6), 68.5 (C2 syn), 67.0 (C2 anti),
63.9 (C1 syn), 62.5 (C1 anti), 48.2 (2 C, NHCH2), 36.3 (PhCH2 an-
ti), 36.1 (PhCH2 syn).
FD-MS: m/z (%) = 170.4 (55, [CH3NH=CHNaph]+), 171.4 (4),
216.4 (33, [ClC6H4CH=NHPh]+), 217.4 (2), 218.4 (8), 386.9 (100,
[M + H]+), 387.9 (32), 388.9 (32), 389.9 (6).
ESI-HRMS: m/z [M + H]+ calcd for C25H23ClN2: 387.1628; found:
387.1642.
FD-MS: m/z (%) = 210.4 (26, [PhC2H4NH=CHPh]+), 211.4 (4),
216.4 (7, [PhCH=NHC6H4Cl]+), 217.4 (1), 218.4 (2), 426.8 (100,
[M + H]+), 427.8 (58), 428.8 (42), 429.8 (18).
ESI-HRMS: m/z [M + H]+ calcd for C28H27ClN2: 427.1941; found:
427.1939.
1-(4-Chlorophenyl)-N1-(4-methylphenyl)-N2-methyl-2-(2-naph-
thyl)ethane-1,2-diamine (8k)
Following the general Method 1, a red oil (667.3 mg) was obtained
from aminonitrile 1c and imine 4b. A portion (143.7 mg) of the
crude product was purified by preparative TLC (SiO2, EtOAc–tolu-
ene, 2:1) to give diamine 8k (80.1 mg, 55%) as a red solid; ratio of
anti/syn isomers = 1.6:1; Rf 0.38, 0.55 (EtOAc–toluene, 2:1).
Anal. Calcd for C28H27ClN2: C, 78.76; H, 6.37; N, 6.56. Found: C,
78.92; H, 6.47; N, 6.46.
IR (film): 3338 (w, NH), 3050 (w), 1617 (m), 1519 (s), 1489 (m),
1089 (m), 750 (m) cm–1.
N1-(4-Chlorophenyl)-1-(1-naphthyl)-N2-(2-phenethyl)-2-phen-
ylethane-1,2-diamine (8i)
Following the general Method 1, a yellow oil (828.4 mg) was ob-
tained from aminonitrile 1b and imine 4f. A portion (134.0 mg) of
the crude product was purified by preparative TLC (SiO2, toluene–
EtOAc, 80:1) to give diamine 8i (54.7 mg, 42%) as a yellow solid;
ratio of anti/syn isomers = 2.3:1; Rf 0.36 (toluene–EtOAc, 80:1).
1H NMR (300 MHz, CDCl3), COSY, HMQC, HMBC (400 MHz,
CDCl3): d = 8.04–5.99 (m, 22 H), 6.85 (pseudo-d, Japp = 7.9 Hz, 2
H, aniline-3,5-H anti), 6.83 (pseudo-d, Japp = 8.3 Hz, 2 H, aniline-
3,5-H syn), 6.38 (pseudo-d, Japp = 8.3 Hz, 2 H, aniline-2,6-H syn),
6.34 (pseudo-d, Japp = 7.9 Hz, 2 H, aniline-2,6-H anti), 5.16 (br s, 1
H, N1H), 4.68 (br s, 1 H, N1H), 4.59 (mc, 1 H, 1-H anti), 4.40 (d,
J = 7.0 Hz, 1 H, 1-H syn), 4.05 (d, J = 5.3 Hz, 1 H, 2-H anti), 3.82
(d, J = 7.0 Hz, 1 H, 2-H syn), 2.35 (s, 1 H, N2H), 2.30 (s, 3 H,
NHCH3 anti), 2.26 (s, 3 H, NHCH3 syn), 2.15 (s, 3 H, ArCH3 syn),
2.14 (s, 3 H, ArCH3 anti), 1.53 (br s, 1 H, N2H).
13C NMR, DEPT (75.5 MHz, CDCl3), HMQC, HMBC (100.6 MHz,
CDCl3): d = 145.1 (aniline-C1 syn), 144.6 (aniline-C1 anti), 140.1,
138.6, 137.5, 136.6, 133.2, 132.7, 129.5, 129.2–122.9 (partly over-
lapping signals), 113.9 (4 C, aniline-C2,6), 70.9 (C2 syn), 69.8 (C2
anti), 63.5 (C1 syn), 62.2 (C1 anti), 34.5 (NHCH3 syn), 34.4
(NHCH3 anti), 20.3 (2 C, ArCH3).
IR (film): 3402 (m, NH), 3061 (m), 3026 (m), 1600 (s), 1496 (vs),
1092 (m), 780 (s), 700 (s) cm–1.
1H NMR (300 MHz, CDCl3): d = 8.24–6.82 (m, 38 H), 6.33–6.18
(m, 4 H, aniline-2,6-H), 5.39 (d, J = 4.4 Hz, 1 H, 1-H anti), 5.14 (d,
J = 3.3 Hz, 1 H, 1-H syn), 4.28 (d, J = 4.4 Hz, 1 H, 2-H anti), 4.19
(d, J = 3.3 Hz, 1 H, 2-H syn), 2.88–2.41 (m, 8 H, HNCH2CH2Ph).
13C NMR, DEPT (75.5 MHz, CDCl3): d = 145.8 (aniline-C1 syn),
145.7 (aniline-C1 anti), 141.0, 139.7, 139.5, 138.5, 135.9, 134.6,
134.3, 133.7, 131.6, 130.9, 130.9, 129.8–122.4 (partly overlapping
signals), 121.9 (aniline-C4 anti), 121.3 (aniline-C4 syn), 114.8 (2 C,
aniline-C2,6 anti), 114.2 (2 C, aniline-C2,6 syn), 66.3 (C2 anti),
Synthesis 2006, No. 21, 3727–3738 © Thieme Stuttgart · New York

PAPER
Synthesis of 1,2-Diamines, 1,2-Diimines, Imidazolium Salts and Imidazolylidenes
3735
FD-MS: m/z (%) = 170.4 (17, [CH3NH=CHNaph]+), 230.5 (12,
[ClC6H4CH=NHTol]+), 232.5 (4), 401.0 (100, [M + H]+), 402.0
(23), 403.0 (38), 404.0 (5).
FD-MS: m/z (%) = 170.3 (90, [NaphCH=NHTol]+), 171.3 (10),
266.4 (68, [NaphCH=NHC6H4Cl]+), 267.4 (16), 268.4 (19), 269.4
(2), 437.8 (100, [M + H]+), 438.8 (54), 439.8 (41), 440.8 (11).
ESI-HRMS: m/z [M + H]+ calcd for C26H25ClN2: 401.1784; found:
ESI-HRMS: m/z [M + H]+ calcd for C29H25ClN2: 437.1785; found:
401.1783.
437.1806.
Anal. Calcd for C26H25ClN2: C, 77.89; H, 6.28; N, 6.99. Found: C,
77.69; H, 6.18; N, 6.95.
1-(4-Chlorophenyl)-N2-isopropyl-N1,2-diphenylethane-1,2-
diamine (8n)
Following the general Method 1, a yellow oil (578.8 mg) was ob-
tained from aminonitrile 1d and imine 4a. A portion (151.5 mg) of
the crude product was purified by preparative TLC (SiO2, toluene–
EtOAc, 10:1) to give diamine 8n (56.6 mg, 35%) as a yellow oil; ra-
tio of anti/syn isomers = 2:1; Rf 0.31, 0.49 (toluene–EtOAc, 10:1).
N1-(4-Chlorophenyl)-N2-methyl-1-phenyl-2-(2-naphth-
yl)ethane-1,2-diamine (8l)
Following the general Method 1, an orange oil (687.1 mg) was ob-
tained from aminonitrile 1c and imine 4e. A portion (175.5 mg) of
the crude product was purified by flash column chromatography
(SiO2, CH2Cl2–toluene, 2:1 + 0.5% EtNMe2) to give diamine 8l
(95.8 mg, 58%) as a yellow solid; ratio of anti/syn isomers = 1.5:1.
Reduction of the diimine 7e according to Method 2A led to diamine
8l in quantitative yield. No further purification was required; ratio
of anti/syn isomers = 1:11; Rf 0.27 (CH2Cl2–toluene, 2:1 + 1%
EtNMe2).
IR (film): 3403 (m, NH), 3051 (w), 3026 (w), 1603 (s), 1504 (vs),
1490 (s), 1090 (m), 750 (s), 693 (s) cm–1.
1H NMR (300 MHz, CDCl3): d = 7.64–6.78 (m, 22 H), 6.68–6.57
(m, 2 H, aniline-4-H), 6.50-6.41 (m, 4 H, aniline-2,6-H), 5.12 (br s,
1 H, N1H), 4.54 (d, J = 4.4 Hz, 1 H, 1-H anti), 4.22 (d, J = 4.4 Hz,
1 H, 2-H anti), 4.20 (d, J = 7.8 Hz, 1 H, 1-H syn), 3.79 (d, J = 7.8
Hz, 1 H, 2-H syn), 2.71–2.51 [m, 2 H, CH(CH3)2], 1.05–0.92 [m, 12
H, CH(CH3)2].
IR (film): 3401 (m, NH), 3354 (m, NH), 3055 (m), 3026 (w), 1600
(s), 1498 (vs), 1091 (m), 816 (s), 702 (s) cm–1.
1H NMR (300 MHz, CDCl3): d = 7.88–6.88 (m, 28 H), 6.37 (m, 4
H, aniline-2,6-H), 5.32 (br s, 1 H, N1H syn), 4.87 (br d, J = 5.5 Hz,
1 H, N1H anti), 4.57 (t, J = 5.5 Hz, 1 H, 1-H anti), 4.42 (d, J = 6.3
Hz, 1 H, 1-H syn), 4.06 (d, J = 5.5 Hz, 1 H, 2-H anti), 3.91 (d,
J = 6.3 Hz, 1 H, 2-H syn), 3.32 (br s, 1 H, N2H), 2.35 (br s, 1 H,
N2H), 2.28 (s, 3 H, CH3 anti), 2.25 (s, 3 H, CH3 syn).
13C NMR, DEPT (75.5 MHz, CDCl3): d = 146.2 (aniline-C1 syn),
145.7 (aniline-C1 anti), 140.8, 139.2, 137.6, 136.7, 133.2, 133.1
(2C), 133.0, 129.4–123.3 (partly overlapping signals), 121.9
(aniline-C4 anti), 121.8 (aniline-C4 syn), 114.8 (4 C, aniline-C2,6),
70.8 (C2 syn), 69.8 (C2 anti), 63.7 (C1 syn), 62.5 (C1 anti), 34.6
(CH3 syn), 34.4 (CH3 anti).
FD-MS: m/z (%) = 170.4 (53, [CH3NH=CHNaph]+), 171.4 (4),
216.4 (24, [ClC6H4CH=NHPh]+), 217.5 (2), 218.4 (6), 386.9 (100,
[M + H]+), 387.9 (35), 388.9 (32), 389.9 (5).
ESI-HRMS: m/z [M + H]+ calcd for C25H23ClN2: 387.1628; found:
387.1642.
13C NMR, DEPT (75.5 MHz, CDCl3): d = 147.8 (aniline-C1 syn),
146.8 (aniline-C1 anti), 140.8, 140.3, 139.7, 137.9, 132.8 (ClC6H4-
C4 anti), 132.5 (ClC6H4-C4 syn), 130.4–126.0 (partly overlapping
signals), 117.6 (aniline-C4 syn), 117.4 (aniline-C4 anti), 114.0 (2 C,
aniline-C2,6 syn), 113.6 (2 C, aniline-C2,6 anti), 66.1 (C2 syn), 64.0
(C2 anti), 63.7 (C1 syn), 61.6 (C1 anti), 45.4 [CH(CH3)2 syn], 45.1
[CH(CH3)2 anti], 24.4 [CH(CH3)2 syn], 24.1 [CH(CH3)2 anti], 22.2
[CH(CH3)2 anti], 21.8 [CH(CH3)2 syn].
FD-MS: m/z (%) = 148.4 (12, [i-PrNH=CHPh]+), 149.4 (1), 216.4
(5, [ClC6H4CH=NHPh]+), 218.5 (2), 364.8 (100, [M + H]+), 365.8
(25), 366.8 (32), 367.8 (8).
ESI-HRMS: m/z [M + H]+ calcd for C23H25ClN2: 365.1784; found:
365.1769.
1-(4-Chlorophenyl)-N2-isopropyl-N1-(4-methylphenyl)-2-
phenylethane-1,2-diamine (8o)
Following the general Method 1, a yellow oil (697.9 mg) was ob-
tained from aminonitrile 1d and imine 4b. A portion (139.8 mg) of
the crude product was purified by preparative TLC (SiO2, toluene–
EtOAc, 10:1) to give diamine 8o (47.8 mg, 37%) as a red oil; ratio
of anti/syn isomers = 1.4:1; Rf 0.21, 0.35 (toluene–EtOAc, 10:1).
N1-(4-Chlorophenyl)-N2-methyl-1-(1-naphthyl)-2-(2-naphth-
yl)ethane-1,2-diamine (8m)
Following the general Method 1, an orange oil (761.4 mg) was ob-
tained from aminonitrile 1c and imine 4f. A portion (154.6 mg) of
the crude product was purified by preparative TLC (SiO2, toluene–
EtOAc, 5:1) to give diamine 8m (82.0 mg, 55%) as a slightly yellow
solid; ratio of anti/syn isomers = 3.2:1. Reduction of the diimine 7f
according to Method 2A led to diamine 8m in quantitative yield. No
further purification was required; ratio of anti/syn isomers = 3:10;
Rf 0.25 (toluene–EtOAc, 5:1).
IR (film): 3402 (s, NH), 3026 (w), 2964 (m), 1617 (m), 1520 (s),
1489 (m), 1090 (m), 700 (s) cm–1.
1H NMR (300 MHz, CDCl3), COSY, HMQC, HMBC (400 MHz,
CDCl3): d = 7.27–6.89 (m, 18 H), 6.89–6.82 (m, 4 H, aniline-3,5-
H), 6.41–6.34 (m, 4 H, aniline-2,6-H), 4.51 (d, J = 4.4 Hz, 1 H, 1-
H anti), 4.19 (d, J = 4.4 Hz, 1 H, 2-H anti), 4.16 (d, J = 7.7 Hz, 1
H, 1-H syn), 3.77 (d, J = 7.7 Hz, 1 H, 2-H syn), 2.73–2.51 [m, 2 H,
CH(CH3)2], 2.15 (s, 6 H, ArCH3), 1.05–0.87 [m, 12 H, CH(CH3)2)].
13C NMR, DEPT (75.5 MHz, CDCl3), HMQC, HMBC (100.6 MHz,
CDCl3): d = 145.5 (aniline-C1 syn), 144.6 (aniline-C1 anti), 140.9,
140.4, 139.7, 138.1, 132.7 (Cl–C6H4-C4 anti), 132.5 (ClC6H4-C4
syn), 129.8–127.1 (partly overlapping signals), 126.8 (aniline-C4
syn), 126.5 (aniline-C4 anti), 114.1 (2 C, aniline-C2,6 syn), 113.8 (2
C, aniline-C2,6 anti), 66.1 (C2 syn), 64.1 (C2 anti), 64.0 (C1 syn),
61.9 (C1 anti), 45.4 [CH(CH3)2 syn], 45.1 [CH(CH3)2 anti], 24.4
[CH(CH3)2 syn], 24.0 [CH(CH3)2 anti)], 22.2 [CH(CH3)2 anti], 21.7
[CH(CH3)2 syn], 20.3 (2 C, ArCH3).
IR (film): 3411 (w, NH), 3054 (m), 1600 (m), 1498 (s), 1266 (vs),
738 (vs), 705 (s) cm–1.
1H NMR (300 MHz, CDCl3), COSY, HMQC, HMBC (400 MHz,
CDCl3): d = 8.71–6.41 (m, 32 H), 6.38–6.21 (m, 4 H, aniline-2,6-
H), 5.56 (d, J = 4.7 Hz, 1 H, 1-H anti), 5.32 (d, J = 2.9 Hz, 1 H, 1-
H syn), 4.32 (d, J = 4.7 Hz, 1 H, 2-H anti), 4.28 (d, J = 2.9 Hz, 1 H,
2-H syn), 2.37 (s, 3 H, CH3 anti), 2.35 (s, 3 H, CH3 syn).
13C NMR, DEPT (75.5 MHz, CDCl3), HMQC, HMBC (100.6 MHz,
CDCl3): d = 145.7 (aniline-C1 syn), 145.6 (aniline-C1 anti), 135.9,
135.8, 134.9, 134.4, 133.9, 133.4, 133.1, 133.0 (2 C), 131.6, 130.9,
129.6–122.4 (partly overlapping signals), 122.1 (aniline-C4 anti),
121.4 (aniline-C4 syn), 114.9 (2 C, aniline-C2,6 anti), 114.2 (2 C,
aniline-C2,6 syn), 69.0 (C2 anti), 68.2 (C2 syn), 59.4 (C1 syn), 57.5
(C1 anti), 34.8 (CH3 syn), 34.4 (CH3 anti).
FD-MS: m/z (%) = 148.3 (7, [i-PrNH=CHPh]+), 230.4 (6,
[ClC6H4CH=NHTol]+), 231.4 (1), 232.4 (1), 378.8 (100, [M + H]+,
379.8 (30), 380.8 (33), 381.8 (9).
Synthesis 2006, No. 21, 3727–3738 © Thieme Stuttgart · New York

3736
C. Kison, T. Opatz
PAPER
ESI-HRMS: m/z [M + H]+ calcd for C24H27ClN2: 379.1941; found:
379.1957.
1-Benzhydryl-4-(4-chlorophenyl)-3,5-diphenyl-1H-imidazoli-
um Chloride (9a)
A solution of the diimine 7c (247.0 mg, 0.51 mmol) and chloro-
methyl ethyl ether (72.2 mg, 0.76 mmol) in anhyd CH2Cl2 (2.5 mL)
was stirred under argon at 40 °C for 8 h. The solvent was removed
in vacuo and the residue was purified by flash column chromatog-
raphy (SiO2, CH2Cl2–MeOH, 10:1 → CH2Cl2–MeOH, 2:1) to give
9b as a yellow resin (176.9 mg, 65%); Rf 0.77 (CH2Cl2–MeOH,
2:1).
N1-(4-Chlorophenyl)-N2-isopropyl-1,2-diphenylethane-1,2-di-
amine (8p)
Following the general Method 1, a yellow oil (595.7 mg) was ob-
tained from aminonitrile 1d and imine 4e. A portion (153.4 mg) of
the crude product was purified by preparative TLC (SiO2, toluene–
EtOAc, 10:1) to give diamine 8p (52.7 mg, 33%) as a yellow oil; ra-
tio of anti/syn isomers = 1.6:1; Rf 0.22, 0.35 (toluene–EtOAc,
10:1).
IR (film): 3062 (w), 2925 (w), 2175 (m), 1542 (s), 1499 (s), 1487
(s), 1455 (s), 1018 (m), 927 (s), 733 (s) cm–1.
IR (film): 3426 (s, NH), 2961 (m), 1620 (s), 1520 (s), 1489 (m),
1090 (m), 700 (s) cm–1.
1H NMR (300 MHz, CDCl3): d = 8.71 (s, 1 H, 2-H), 7.68–7.60 (m,
2 H), 7.45–7.02 (m, 22 H), 6.73 (s, 1 H, Ph2CH).
13C NMR, DEPT (75.5 MHz, CDCl3): d = 136.0, 135.3, 135.2 (2 C),
133.6, 133.3, 132.2 (2 C), 131.4 (2 C), 130.5, 130.3, 129.8 (2 C),
129.3–129.1 (partly overlapping signals), 128.8 (2 C), 128.7 (2 C),
126.9 (2 C), 124.9, 123.2, 67.0 (Ph2CH).
1H NMR (300 MHz, CDCl3): d = 7.34–6.71 (m, 24 H), 6.39 (pseu-
do-d, Japp = 8.8 Hz, 4 H, aniline-2,6-H), 4.53 (d, J = 4.6 Hz, 1 H, 1-
H anti), 4.24–4.22 (m, 2 H, 2-H anti, 1-H syn), 3.88 (d, J = 7.4 Hz,
1 H, 2-H syn), 2.76–2.46 [m, 2 H, CH(CH3)2], 1.60 (br s, 1 H, N2H),
1.09–0.85 [m, 12 H, CH(CH3)2].
13C NMR (75.5 MHz, CDCl3): d = 146.5 (aniline-C1 syn), 145.7
(aniline-C1 anti), 140.9, 140.6, 139.5, 138.6, 129.0–126.9 (partly
overlapping signals), 121.9 (aniline-C4 syn), 121.7 (aniline-C4 an-
ti), 115.0 (2 C, aniline-C2,6 syn), 114.8 (2 C, aniline-C2,6 anti),
65.9 (C2 syn), 64.1 (C2 anti), 64.0 (C1 syn), 62.1 (C1 anti), 45.6
[CH(CH3)2 syn], 45.2 [CH(CH3)2 anti], 24.1 [CH(CH3)2 syn], 24.0
[CH(CH3)2 anti], 22.0 [CH(CH3)2 anti], 21.5 [CH(CH3)2 syn].
FD-MS: m/z (%) = 330.0 (100, [M – Ph2CH]+), 331.0 (20), 331.9
(35),496.9 (72, [M]+), 496.9 (72), 497.9 (22), 498.9 (36), 500.0 (7).
ESI-HRMS: m/z [M]+ calcd for C34H26ClN2: 497.1779; found:
497.1765.
1-Benzhydryl-4-(4-chlorophenyl)-3-(4-methylphenyl)-5-phen-
yl-1H-imidazolium Trifluoromethanesulfonate (9b)
A solution of the diimine 7b (222.4 mg, 0.45 mmol), chloromethyl
pivalate (94.0 mg, 0.62 mmol) and silver trifluoromethanesulfonate
(137.4 mg, 0.53 mmol) in anhyd CH2Cl2 (2 mL) was stirred under
argon at 40 °C for 16 h in the dark. After filtration, the solvent was
removed in vacuo, and the residue was purified by flash column
chromatography (SiO2, cyclohexane–EtOAc, 10:1 + 0.5% EtNMe2)
to give 9a as a brownish oil (62.3 mg, 21%); Rf 0.18 (cyclohexane–
EtOAc, 10:1 + 1% EtNMe2).
FD-MS: m/z (%) = 148.3 (12, [i-PrNH=CHPh]+), 216.4 (9,
[ClC6H4CH=NHPh]+), 217.4 (2), 218.4 (3), 364.7 (100, [M + H]+),
365.7 (26), 366.7 (29), 367.7 (7).
ESI-HRMS: m/z [M + H]+ calcd for C23H25ClN2: 365.1784; found:
365.1781.
N1-(4-Chlorophenyl)-N2-isopropyl-1-(1-naphthyl)-2-phenyl-
ethane-1,2-diamine (8q)
IR (film): 1642 (m), 1264 (m), 1157 (m), 1032 (m), 701 (m), 638 (s)
cm–1.
1H NMR (300 MHz, CDCl3), HMQC, HMBC (400 MHz, CDCl3):
d = 8.00 (s, 1 H, 2-H), 7.45–6.96 (m, 23 H), 6.66 (s, 1 H, Ph2CH),
2.30 (s, 3 H, CH3).
13C NMR, DEPT (75.5 MHz, CDCl3), HMQC, HMBC (100.6 MHz,
CDCl3): d = 141.0 (aniline-C4), 136.0 (ClC6H4-C4), 135.0, 134.2
(1JC,H = 222 Hz, C2), 133.5 (C5), 133.1 (C4), 132.2 (2 C, ClC6H4-
C2,6), 131.3, 130.9 (aniline-C1), 130.4 (2 C, aniline-C3,5), 130.2,
129.4, 128.9–128.6 (partly overlapping signals), 120.8 (q,
1JC,F = 321 Hz, CF3), 126.3 (2 C, aniline-C2,6), 66.8 (Ph2CH), 21.1
(CH3).
Following general Method 1, a yellow oil (815.4 mg) was obtained
from aminonitrile 1d and imine 4f. A portion (161.2 mg) of the
crude product was purified by preparative TLC (SiO2, toluene–
EtOAc, 40:1) to give diamine 8q (44.6 mg, 32%) as a viscous yel-
low oil; ratio of anti/syn isomers = 4.3:1; Rf 0.42 (toluene–EtOAc,
40:1).
IR (film): 3401 (m, NH), 3060 (w), 1599 (m), 1496 (s), 1092 (m),
702 (m) cm–1.
1H NMR (300 MHz, CDCl3): d = 8.25–6.63 (m, 28 H), 6.43–6.26
(m, 4 H, aniline-2,6-H), 5.48 (d, J = 3.8 Hz, 1 H, 1-H anti), 5.12 (d,
J = 4.3 Hz, 1 H, 1-H syn), 4.45 (d, J = 3.8 Hz, 1 H, 2-H anti), 4.23
(d, J = 4.3 Hz, 1 H, 2-H syn), 2.78–2.41 [m, 2 H, CH(CH3)2], 1.17–
0.86 [m, 12 H, CH(CH3)2].
13C NMR, DEPT (75.5 MHz, CDCl3): d = 146.1 (aniline-C1 syn),
145.6 (aniline-C1 anti), 141.7, 138.6, 136.4, 134.7, 134.2, 133.7,
131.6, 131.0, 129.6–122.1 (partly overlapping signals), 121.9
(aniline-C4 anti), 121.4 (aniline-C4 syn), 114.8 (2 C, aniline-C2,6
anti), 114.4 (2 C, aniline-C2,6 syn), 63.9 (C2 syn), 63.2 (C2 anti),
59.5 (C1 syn), 57.4 (C1 anti), 46.0 [CH(CH3)2 syn], 45.4 [CH(CH3)2
anti], 24.2 [CH(CH3)2 syn], 23.9 [CH(CH3)2 anti], 22.1 [CH(CH3)2
anti], 21.7 [CH(CH3)2 syn].
FD-MS: m/z (%) = 511.1 (100, [M]+), 512.2 (40), 513.2 (36), 514.2
(13), 515.2 (2).
ESI-HRMS: m/z [M]+ calcd for C35H28ClN2: 511.1936; found:
511.1931.
1-Benzhydryl-3-(4-chlorophenyl)-4,5-diphenyl-1H-imidazoli-
um Chloride (9c)
A solution of the diimine 7c (247.1 mg, 0.57 mmol) and chloro-
methyl methyl ether (63.6 mg, 0.79 mmol) in anhyd CH2Cl2 (3 mL)
was stirred under argon at 40 °C for 16 h. The solvent was removed
in vacuo and the residue was purified by flash column chromatog-
raphy (SiO2, CH2Cl2–MeOH, 10:1 → CH2Cl2–MeOH, 1:1) to give
9c as a reddish resin (218.9 mg, 72%); Rf 0.06 (CH2Cl2–MeOH,
10:1).
FD-MS: m/z (%) = 148.4 (12, [i-PrNH=CHPh]+), 266.5 (10,
[NaphCH=NHC6H4Cl]+), 267.5 (1), 268.5 (4), 414.9 (100, [M +
H]+), 415.9 (41), 416.9 (36), 417.9 (11).
ESI-HRMS: m/z [M + H]+ calcd for C27H27ClN2: 415.1941; found:
415.1948.
IR (film): 2926 (m), 2855 (m), 1543 (m), 1494 (s), 1455 (m), 1090
(m), 910 (s), 732 (s), 699 (s) cm–1.
1H NMR (300 MHz, CDCl3): d = 9.11 (s, 1 H, 2-H), 7.82–7.03 (m,
24 H), 6.69 (s, 1 H, Ph2CH).
Anal. Calcd for C27H27ClN2: C, 78.15; H, 6.56; N, 6.75. Found: C,
78.03; H, 6.53; N, 6.85.
Synthesis 2006, No. 21, 3727–3738 © Thieme Stuttgart · New York

PAPER
Synthesis of 1,2-Diamines, 1,2-Diimines, Imidazolium Salts and Imidazolylidenes
3737
13C NMR, DEPT (75.5 MHz, CDCl3): d = 136.5, 135.8 (C2), 135.1
(2 C, 4-ClC6H4), 133.5, 133.0, 132.1, 131.4, 130.7, 130.3, 130.1–
126.2 (partly overlapping signals), 124.9, 124.4, 121.2, 67.2
(Ph2CH).
FD-MS: m/z (%) = 497.4 (100, [M]+), 498.4 (33), 499.4 (33), 500.4
(10).
the solvent was removed in vacuo to give the thione 11 (36.5 mg,
quant) as a yellow oil; Rf 0.71 (petroleum ether–EtOAc, 10:1).
IR (film): 3364 (w), 3060 (m), 2928 (m), 1498 (s), 1365 (s), 1323
(s), 1090 (m), 1016 (m) cm–1.
1H NMR (300 MHz, CDCl3), HMQC, HMBC (400 MHz, CDCl3):
d = 8.10 (br s, 1 H, Ph2CH), 7.41–6.86 (m, 29 H), 6.72 (pseudo-d,
Japp = 8.5 Hz, 2 H), 6.63 (pseudo-d, Japp = 7.2 Hz, 2 H).
ESI-HRMS: m/z [M]+ calcd for C34H26ClN2: 497.1779; found:
497.1779.
13C NMR, DEPT (75.5 MHz, CDCl3), HMQC, HMBC (100.6 MHz,
CDCl3): d = 166.1, 137.6 [2 C, (C6H5)2CHC1), 137.2, 133.8
(ClC6H4), 131.9 (2 C), 131.2 (2 C), 129.1–127.7 (partly overlapping
signals, including C5), 127.4 [2 C, (C6H5)2CH, C4 arom), 126.4
(C4), 64.4 (Ph2CH).
FD-MS: m/z (%) = 528.1 (100, [M]+), 529.1 (36), 530.1 (42), 531.1
(15).
4-(4-Chlorophenyl)-3-(4-methylphenyl)-1-phenethyl-5-phenyl-
1H-imidazolium Chloride (9d)
This compound was prepared as described for 9c from diimine 7d
(59.3 mg, 0.14 mmol) and chloromethyl methyl ether (15.3 mg,
0.19 mmol). The crude product was purified by flash column chro-
matography (SiO2, CH2Cl2 → CH2Cl2–MeOH, 1:1) to give 9d as a
red oil (59.8 mg, 76%); Rf 0.10 (CH2Cl2–MeOH, 15:1).
ESI-HRMS: m/z [M]+ calcd for C34H25ClN2S: 529.1505; found:
529.1523.
IR (film): 1590 (s), 1549 (s), 1092 (m), 753 (m), 702 (s) cm–1.
1H NMR (300 MHz, CDCl3): d = 10.88 (s, 1 H, 2-H), 7.58–7.32 (m,
4 H), 7.23–7.05 (m, 12 H), 6.81 (pseudo-d, Japp = 8.6 Hz, 2 H,
aniline-3,5-H), 4.74 (t, J = 7.5 Hz, 2 H, NHCH2), 3.09 (t, J = 7.5 Hz,
2 H, CH2Ph), 2.31 (s, 3 H, CH3).
13C NMR, DEPT (75.5 MHz, CDCl3): d = 140.8 (C2H4C6H5-C1),
138.3 (C2), 136.2, 136.0, 132.3, 132.2, 131.9, 131.5 (2 C, aniline-
C3,5), 124.6, 123.3, 49.0 (NHCH2), 36.4 (CH2Ph), 21.2 (CH3).
Acknowledgment
This work was supported by the Deutsche Forschungsgemeinschaft,
the Fonds der Chemischen Industrie and the University of Mainz.
We thank Dr. D. Schollmeyer for the X-ray crystallographic analy-
sis of compound 3 and H. Kolshorn for performing the 2D-NMR ex-
periments and the NOE measurements.
FD-MS: m/z (%) = 449.3 (100, [M]+), 450.3 (28), 451.3 (34), 452.3
(9).
References
ESI-HRMS: m/z [M]+ calcd for C30H26ClN2: 449.1779; found:
449.1780.
(1) For an excellent review of the chemistry of 1,2-diamines,
see: Lucet, D.; Len Gall, T.; Mioskowski, C. Angew. Chem.
Int. Ed. 1998, 37, 2580; Angew. Chem. 1998, 110, 2724.
(2) Reedijk, J. Chem. Commun. 1996, 801.
(3) Mukaiyama, T.; Soai, K.; Sato, T.; Shimizu, H.; Suzuki, K.
J. Am. Chem. Soc. 1979, 101, 1455.
(4) Corey, E. J.; Hannon, F. J. Tetrahedron Lett. 1987, 28, 5233.
(5) Kobayashi, S.; Uchiro, H.; Fujishita, Y.; Shiina, I.;
Mukaiyama, T. J. Am. Chem. Soc. 1991, 113, 4247.
(6) Corey, E. J.; Imwinkelried, R.; Pikul, S.; Xiang, Y. B. J. Am.
Chem. Soc. 1989, 111, 5493.
(7) Corey, E. J.; Sarshar, S.; Bordner, J. J. Am. Chem. Soc. 1992,
114, 7938.
(8) Pikul, S.; Corey, E. J. Org. Synth. 1993, 71, 30.
(9) Sato, T.; Goto, Y.; Fujisawa, T. Tetrahedron Lett. 1982, 23,
4111.
(10) Mukaiyama, T.; Tomimori, K.; Oriyama, T. Chem. Lett.
1985, 813.
(11) Kolb, H. C.; VanNieuwenhze, M. S.; Sharpless, K. B. Chem.
Rev. 1994, 94, 2483.
(12) Hanessian, S.; Meffre, P.; Girard, M.; Beaudoin, S.;
Sancéau, J.-Y.; Bennani, Y. J. Org. Chem. 1993, 58, 1991.
(13) Lounasmaa, M.; Hanhinen, P. In The Alkaloids, Vol. 55;
Cordell, G., Ed.; Academic Press: New York, 2001, 1–89.
(14) Kohmoto, S.; Kashman, Y.; McConnell, O. J.; Rinehart, K.
L. Jr.; Wright, A.; Koehn, F. J. Org. Chem. 1988, 53, 3116.
(15) Rinehart, K. L.; Kobayashi, J.; Harbour, G. C.; Hughes, R.
G. Jr.; Mizsak, S. A.; Scahill, T. A. J. Am. Chem. Soc. 1984,
106, 1524.
3-(4-Chlorophenyl)-1-methyl-5-(2-naphthyl)-4-(1-naphthyl)-
1H-imidazolium Tetraphenylborate (9e)
This compound was prepared as described for 9c from diimine 7f
(204.6 mg, 0.51 mmol) and chloromethyl methyl ether (57.9 mg,
0.72 mmol). The crude product was purified by flash column chro-
matography (SiO2, CH2Cl2–MeOH, 15:1 → CH2Cl2–MeOH, 1:1) to
give the imidazolium chloride as a red oil (207.6 mg, 85%). A por-
tion (166.5 mg) of the imidazolium chloride was then treated with
sodium tetraphenylborate (118.4 mg, 0.35 mmol) as described in
the literature59 to yield 120.6 mg (45%) of the corresponding imida-
zolium tetraphenylborate 9e as a beige solid; mp 61–62 °C; Rf 0.16
(CH2Cl2–MeOH, 10:1).
IR (film): 3056 (m), 1595 (m), 1556 (m), 1495 (s), 1094 (m), 738
(s), 705 (s) cm–1.
1H NMR (300 MHz, CDCl3): d = 8.56 (s, 1 H, 2-H), 7.88–6.77 (m,
38 H), 3.75 (s, 3 H, CH3).
13C NMR, DEPT (75.5 MHz, CDCl3): d = 138.3 (C2), 136.3 (1-
naphthyl-C1), 134.8, 134.2, 133.6, 133.2, 132.6, 132.1, 132.0,
131.4, 131.2, 131.0, 130.5–127.1 (partly overlapping signals),
126.8, 126.4, 126.0, 125.0, 124.2, 121.8, 121.5, 119.8, 115.6 (2 C,
aniline-C2,6), 35.7 (CH3).
FD-MS: m/z (%) = 445.2 (100, [M]+), 446.2 (35), 447.2 (35), 448.2
(11).
ESI-HRMS: m/z [M]+ calcd for C30H22ClN2: 445.1466; found:
445.1475.
(16) Gasc, M. B.; Lattes, A.; Perie, J. J. Tetrahedron 1983, 39,
703.
(17) Moriarty, R. M.; Khosrowshahi, J. S. Tetrahedron Lett.
1986, 27, 2809.
(18) Sharpless, K. B.; Chong, A. O.; Oshima, K. J. Org. Chem.
1976, 41, 177.
(19) Feit, P. W.; Nielsen, O. T. J. Med. Chem. 1967, 10, 927.
(20) VanderWerf, R.; Heisler, R. Y.; McEwen, W. E. J. Am.
Chem. Soc. 1954, 76, 1231.
1-Benzhydryl-4-(4-chlorophenyl)-3,5-diphenyl-1,3-dihydroimi-
dazole-2-thione (11)
To a stirred solution of the imidazolium salt 9b (36.4 mg, 0.068
mmol) in anhyd THF (4 mL), was added t-BuLi (40 mL of a 1.7 M
solution in pentane, 0.068 mmol) at r.t. under argon. The deep red
solution was stirred for 30 min, then sulfur (3.00 mg, 0.094 mmol)
was added and the mixture was stirred overnight. After filtration,
Synthesis 2006, No. 21, 3727–3738 © Thieme Stuttgart · New York

3738
C. Kison, T. Opatz
PAPER
(21) von Miller, W.; Plöchl, J. Ber. Dtsch. Chem. Ges. 1892, 25,
2020.
(42) Lu, Z.-H.; Bhongle, N.; Su, X.; Ribe, S.; Senanayake, C. H.
Tetrahedron Lett. 2002, 43, 8617.
(22) Khan, N. H.; Zuberi, R. H.; Siddiqui, A. A. Synth. Commun.
1980, 10, 363.
(23) Bernardi, L.; Bonini Bianca, F.; Capito, E.; Dessole, G.;
Comes-Franchini, M.; Fochi, M.; Ricci, A. J. Org. Chem.
2004, 69, 8168.
(24) Kise, N.; Kashiwagi, K.; Watanabe, M.; Yoshida, J. J. Org.
Chem. 1996, 61, 428.
(43) Glorius, F.; Altenhoff, G.; Goddard, R.; Lehmann, C. Chem.
Commun. 2002, 2704. This method yields imidazolium
triflates which are more soluble in nonpolar solvents than the
corresponding chlorides..
(44) Arduengo, A. J. III; Krafczyk, R.; Schmutzler, R.; Craig, H.
A.; Goerlich, J. R.; Marshall, W. J.; Unverzagt, M.
Tetrahedron 1999, 55, 14523.
(25) Meyer, N.; Opatz, T. Synlett 2003, 1427.
(26) Meyer, N.; Opatz, T. Synlett 2004, 787.
(27) Meyer, N.; Werner, F.; Opatz, T. Synthesis 2005, 945.
(28) Kison, C.; Meyer, N.; Opatz, T. Angew. Chem. Int. Ed. 2005,
44, 5662; Angew. Chem. 2005, 117, 5807.
(29) For the addition of a deprotonated Reissert-compound to an
imine, see: Kant, J. J. Heterocycl. Chem. 1990, 27, 2129.
(30) CCDC 601965 contains the supplementary crystallographic
data for this paper. These data can be obtained free of charge
from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
(45) Huang, J.; Stevens, E. D.; Nolan, S. P.; Petersen, J. L. J. Am.
Chem. Soc. 1999, 121, 2674.
(46) Fürstner, A.; Thiel, O. R.; Ackermann, L.; Schanz, H.-J.;
Nolan, S. P. J. Org. Chem. 2000, 65, 2204.
(47) For a review on stable carbenes, see: Bourissou, D.; Guerret,
O.; Gabbai, F. P.; Bertrand, G. Chem. Rev. 2000, 100, 39.
(48) For a review on N-heterocyclic carbenes in catalysis, see:
Herrmann, W. A. Angew. Chem. Int. Ed. 2002, 42, 1290;
Angew. Chem. 2002, 114, 1342.
(49) Hassan, N. A.; Bayer, E.; Jochims, J. C. J. Chem. Soc.,
Perkin Trans. 1 1998, 3747.
(31) Reich, B. J. E.; Greenwald, E. E.; Justice, A. K.; Beckstead,
B. T.; Reibenspies, J. H.; North, S. W.; Miller, S. A. J. Org.
Chem. 2005, 70, 8409.
(50) Leblanc, J.-P.; Gibson, H. W. J. Org. Chem. 1994, 59, 1072.
(51) Ranu, B. C.; Dey, S. S.; Hajra, A. Tetrahedron 2002, 58,
2529.
(52) Maccarone, E.; Mamo, A.; Musumarra, G.; Scarlata, G.;
Tomaselli, G. A. J. Org. Chem. 1977, 42, 3024.
(53) Tsuge, O.; Koga, M.; Shinkai, I. Tetrahedron 1973, 29, 259.
(54) Hess, U.; Thiele, R. J. Prakt. Chem. 1982, 324, 385.
(55) Mesli, A.; Tirouflet, J. Bull. Soc. Chim. Fr. 1975, 1753.
(56) Cavallito, C. J.; Yun, H. S.; Edwards, M. L.; Foldes, F. F. J.
Med. Chem. 1971, 14, 130.
(32) Becker, H.-D. J. Org. Chem. 1970, 35, 2099.
(33) Strain, H. H. J. Am. Chem. Soc. 1928, 50, 2218.
(34) Walia, J. S.; Guillot, L.; Singh, J.; Chatta, M. S.;
Satyanarayana, M. J. Org. Chem. 1972, 37, 135.
(35) Reich, B. J. E.; Justice, A. K.; Beckstead, B. T.; Reibenspies,
J. H.; Miller, S. A. J. Org. Chem. 2004, 69, 1357.
(36) Jaunin, R.; Courbat, P. Helv. Chim. Acta 1961, 44, 309.
(37) Ohtaka, S.; Mori, K.; Uemura, S. Heteroat. Chem. 2001, 12,
309.
(57) Prot, T. Rocz. Chem. 1971, 45, 247; Chem. Abstr. 1971, 75,
26791g.
(38) Periasamy, M.; Srinivas, G.; Karunakar, G. V.; Bharathi, P.
(58) Davis, F. A.; Lamendola, J.; Nadir, U.; Kluger, E. W.;
Sedergran, T. C.; Panunto, T. W.; Billmers, R.; Jenkins, R.;
Turchi, I. J.; Watson, W. H.; Chen, J. S.; Kimura, M. J. Am.
Chem. Soc. 1980, 102, 2000.
Tetrahedron Lett. 1999, 40, 7577.
(39) Mangeney, P.; Tejero, T.; Alexakis, A.; Grosjean, F.;
Normant, J. Synthesis 1988, 255.
(40) Hatano, B.; Ogawa, A.; Hirao, T. J. Org. Chem. 1998, 63,
(59) Dupont, J.; Suarez, P. A. Z.; De Souza, R. F.; Burrow, R. A.;
9421.
Kintzinger, J.-P. Chemistry 2000, 6, 2377.
(41) Largeron, M.; Fleury, M.-B. J. Org. Chem. 2000, 65, 8874.
Synthesis 2006, No. 21, 3727–3738 © Thieme Stuttgart · New York