Diverse reactions of 1,4-dilithio-1,3-dienes with nitrites: Facile access to tricyclic Δ1-bipyrrolines, multiply substituted pyridines, siloles, and (Z,Z)-dienylsilanes by tuning of substituents on the butadienyl skeleton

Article abstract of DOI:10.1002/chem.200701742

Addition cyclization of 1,2,3,4-tetrasubstituted 1,4-dilithio-1,3-dienes (Type I) with four equivalents of various aromatic nitriles in the presence of hexamethylphosphoramide (HMPA) gives exclusively fully substituted pyridines in moderate to good yields. Similarly, trisubstituted pyridines can be prepared by the reaction of 2,3-dialkyl- or diaryl-substituted 1,4dilithio-1,3-dienes (Type II) with nitriles. However, five- or six-memberedring fused 2,3-disubstituted 1,4-dilithio1,3-dienes (Type III) reacted with various aromatic and aliphatic nitriles without a-hydrogen atoms to afford tricyclic Δ¹- bipyrrolines in high yields. The reaction of six-membered-ring fused 2,3-disubstituted 1,4-dilithio-1,3-diene (Type III) with 2-cyanopyridine afforded the corresponding pyridine, and no tricyclic Δ¹- bipyrroline was observed. Seven-membered-ring fused dilithiodienes reacted with PhCN or trimethylacetonitrile to afford the corresponding pyridines in good yield. When 1,2,3,4-tetrasubstituted dilithio reagents (Type I) were treated with Me₃SiCN, a tandem silylation/intramolecular substitution process readily occurred to yield siloles, whereas the reaction of 2,3-disubstituted dilithio reagents (Types II and III) with Me₃SiCN gave rise to (Z,Z)-dienylsilanes with high stereoselectivity. These results revealed that the formation of tricyclic Δ¹-bipyrrolines, pyridines, siloles, and (Z,Z)-dienylsilanes are strongly dependent on the substitution patterns of the dilithio butadienes and the nature of the nitriles employed.

Full text of DOI:10.1002/chem.200701742

DOI: 10.1002/chem.200701742
Diverse Reactions of 1,4-Dilithio-1,3-dienes with Nitriles: Facile Access to
Tricyclic D1-Bipyrrolines, Multiply Substituted Pyridines, Siloles, and
(Z,Z)-
G
Dienylsilanes by Tuning of Substituents on the Butadienyl Skeleton
Nan Yu,[a] Congyang Wang,[a] Fei Zhao,[a] Lantao Liu,[b] Wen-Xiong Zhang,[a] and
Zhenfeng Xi*[a, c]
Abstract: Addition cyclization of
1,2,3,4-tetrasubstituted 1,4-dilithio-1,3-
dienes (Type I) with four equivalents of
various aromatic nitriles in the pres-
ence of hexamethylphosphoramide
(HMPA) gives exclusively fully substi-
tuted pyridines in moderate to good
yields. Similarly, trisubstituted pyri-
dines can be prepared by the reaction
of 2,3-dialkyl- or diaryl-substituted 1,4-
dilithio-1,3-dienes (Type II) with ni-
triles. However, five- or six-membered-
ring fused 2,3-disubstituted 1,4-dilithio-
1,3-dienes (Type III) reacted with vari-
ous aromatic and aliphatic nitriles with-
out a-hydrogen atoms to afford tricy-
clic D1-bipyrrolines in high yields. The
reaction of six-membered-ring fused
2,3-disubstituted 1,4-dilithio-1,3-diene
(Type III) with 2-cyanopyridine afford-
ed the corresponding pyridine, and no
tricyclic D1-bipyrroline was observed.
Seven-membered-ring fused dilithio-
dienes reacted with PhCN or trimethy-
lacetonitrile to afford the correspond-
ing pyridines in good yield. When
1,2,3,4-tetrasubstituted dilithio reagents
(Type I) were treated with Me3SiCN, a
tandem silylation/intramolecular substi-
tution process readily occurred to yield
siloles, whereas the reaction of 2,3-dis-
ubstituted dilithio reagents (Types II
and III) with Me3SiCN gave rise to
(Z,Z)-dienylsilanes with high stereose-
lectivity. These results revealed that
the formation of tricyclic D1-bipyrro-
lines, pyridines, siloles, and (Z,Z)-dien-
ylsilanes are strongly dependent on the
substitution patterns of the dilithio bu-
tadienes and the nature of the nitriles
employed.
Keywords: cyclization
·
nitrogen
heterocycles · polycycles · silanes ·
synthetic methods
Introduction
Organolithium compounds have a prominent role as reac-
tive organometallic reagents throughout organic and inor-
ganic synthesis.[1] The addition reaction of organolithium
compounds to nitriles to give N-lithio ketimines is among
the fundamental processes of organometallic chemistry.
Generally, the intermolecular trapping of N-lithio ketimines
with organic halides or protons yields imines and ketones.[2]
N-Lithio ketimines can also be trapped with carbon monox-
ide to afford N-containing cyclic compounds.[3] Correspond-
ingly, the trapping of N-lithio ketimines with intramolecular
organic halides provides a useful route to construct N-con-
taining heterocycles such as pyridines.[4,5] However, trapping
N-lithio ketimines with intramolecular C=C bonds has
seldom been explored.[6,7]
[a] N. Yu, Dr. C. Wang, F. Zhao, Prof. Dr. W.-X. Zhang, Prof. Dr. Z. Xi
Beijing National Laboratory for Molecular Sciences (BNLMS)
Key Laboratory of Bioorganic Chemistry and
Molecular Engineering of Ministry of Education
College of Chemistry, Peking University, Beijing 100871 (China)
Fax : (+86)10-6275-9728
E-mail: zfxi@pku.edu.cn
[b] L. Liu
Institute of Chemistry
Chinese Academy of Sciences
Beijing 100080 (China)
[c] Prof. Dr. Z. Xi
State Key Laboratory of Organometallic Chemistry
Shanghai Institute of Organic Chemistry
Chinese Academy of Sciences, Shanghai 200032 (China)
The development of synthetically useful methods for the
preparation of N-containing heterocycles such as substituted
pyridines and D1-pyrrolines has continuously been an attrac-
tive research topic in synthetic chemistry, because D1-pyrro-
Supporting information for this article is available on the WWW
under http://www.chemeurj.org/ or from the author.
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FULL PAPER
Table 1. Reactions of 1,2,3,4-tetrapropyl-1,4-dilithio-1,3-diene with differ-
ent amount of nitrile.
line derivatives in particular can serve as building blocks for
many biologically relevant compounds[8] and as important
synthetic intermediates in organic synthesis.[9] Among the
many synthetic methods for various substituted pyridines
and D1-pyrrolines,[10,11] the addition of organolithium com-
pounds to nitriles provides an alternatively efficient method.
There is only one report on the synthesis of D1-bipyrroline
by the reaction of the 2,3-dimethylenebutadiene dianion
with benzonitrile.[12] As far as we are aware, the synthesis of
tricyclic D1-bipyrrolines has not been reported.
We have recently found that addition cyclization of 1-
lithio-1,3-dienes with aromatic nitriles affords multiply sub-
stituted pyridines, pyrroles, and linear butadienyl imines, de-
pending on the substituents on the butadienyl skeleton.[7]
Herein we report reactions of various substituted dilithio re-
agents such as 1,2,3,4-tetrasubstituted 1,4-dilithio-1,3-dienes,
2,3-disubstituted 1,4-dilithio-1,3-dienes, and cyclic 2,3-disub-
stituted 1,4-dilithio-1,3-dienes (Scheme 1, Types I–III) with
Nitrile
[equiv]
Yield of
Yield of
Yield of
G
2a [%][a]
3a [%][b]
4a [%][a]
1
2
3
4
16
35
50
62
49
55
57
60
51
30
0
0
[a] Yield of isolated product. [b] Yield of isolated product calculated
based on nitrile.
However, 2a was isolated in 62% yield of in the presence of
four equivalents of PhCN.
Four equivalents of nitrile were then chosen as the stan-
dard amount for the present reaction. Representative results
are summarized in Tables 2 and 3. As shown in Table 2, a
wide range of aromatic nitriles react with 1,2,3,4-tetrasubsti-
tuted 1,4-dilithio-1,3-dienes (Type I) to afford fully substitut-
ed pyridines in moderate to good yields (Table 2). The aro-
Scheme 1. Variously substituted 1,4-dilithio-1,3-dienes.
nitriles to yield a series of substituted tricyclic D1-bipyrro-
lines, pyridines, siloles, and dienylsilanes that can not be
readily obtained by other means. In these processes, the sub-
stitution patterns on the butadienyl skeleton play a vital role
in determining the structure of the products. Furthermore,
À
matic C Br bond could survive under the present conditions
(Table 2, entry 4), although it is vulnerable to organolithium
reagents. The reaction of PhCN with a tetrasubstituted di-
lithium compound having a fused six-membered ring gave
À
cleavage of the Si C bond in the SiCN moiety was ob-
served,[13] which is in contrast to the normal reaction pat-
exclusively tetrahydroisoquinoline 2j in a high yield
ꢀ
tern, in which nitriles are attacked at the C N bond by orga-
nolithium reagents. A portion of this work on the synthesis
(Table 2, entry 9).
2,3-Dialkyl- and diaryl-substituted 1,4-dilithio-1,3-dienes 5
(Type II) can undergo smooth addition cyclization with aro-
matic nitriles to yield trisubstituted pyridines 6 (Table 3).
Heteroatom-containing nitriles such as 2-cyanopyridine
were also employed in this reaction to yield 2,2’-bipyridines
(Table 2, entry 8 and Table 3, entries 4–6). The reaction of
PhCN with dilithium reagent 5d having a seven-membered
ring in the 2,3-positions gave exclusively pyridine 6g in 56%
yield. The reaction of trimethylacetonitrile with dilithium 5d
gave exclusively pyridine 6h, although aliphatic nitriles with
a-hydrogen atoms were not suitable for this reaction, proba-
bly because of rapid protonolysis of the dilithium com-
pounds by the a-hydrogen atoms. However, when the di-
lithium compounds 5a,e were treated with trimethylacetoni-
trile, corresponding pyridines 6i,j were isolated in 29 and
22% yield, respectively. After careful investigation into this
reaction, unexpected D1-bipyrrolines 7a,b were character-
ized (Scheme 2). However, attempts to obtain the D1-bipyr-
rolines as the only products by reaction of these dilithium
compounds (Types I and II) with trimethylacetonitrile were
unsuccessful.
of pyridines was communicated previously.[7a]
Results and Discussion
Formation of pyridines: Unlike the reaction of 1-lithio-1,3-
dienes with nitriles,[7a,b] an excess of nitrile is necessary to
ensure high-yield formation of pyridines from 1,4-lithio-1,3-
dienes because of self-cyclotrimerization of nitriles leading
to the formation of triazines as by-products.[14] To optimize
the reaction conditions, the reactions of 1,2,3,4-tetrapropyl-
1,4-dilithio-1,3-diene (1a), generated in situ by lithiation of
the corresponding 1,4-diiodo-1,3-diene,[15] with different
amounts of benzonitrile (PhCN) in the presence of hexame-
thylphosphoramide (HMPA) were conducted (Table 1).
When one equivalent of PhCN was employed, pyridine 2a
was isolated in only 16% yield along with triazine 3a in
49% yield. Simultaneously, diene 4a was recovered in 51%
yield, derived from hydrolysis of 1a. At least three equiva-
lents of PhCN are required for complete consumption of 1a.
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Z. Xi et al.
Table 2. Reaction of 1,2,3,4-tetrasubstitued 1,4-dilithio-1,3-dienes with ar-
omatic nitriles.
Table 3. Reaction of 2,3-disubstituted 1,4-dilithio-1,3-dienes with aromat-
ic nitriles.
Entry Dilithium 5
Nitrile
Pyridine 6
Isolated
product
Entry
Nitrile
Pyridine 2
Isolated
product
A
A
1
6a (60)
6b (59)
1
2b (63)
2
5a
2
3
4
2c (80)
2d (60)
2e (53)
3
4
5
6
6c (57)
6d (86)
6e (60)
6 f (58)
5a
5b
5
6
2 f (58)
7
8
6g (56)
6h (60)
5d
2g (55)
7
8
9
2h (57)
2i (55)
2j (73)
Scheme 2. Reaction of 2,3-disubstituted 1,4-dilithio-1,3-dienes with trime-
thylacetonitrile.
and cyclopentadienyl amine 8a was formed, even at temper-
ature as low as À1308C, along with 1a. When the reaction
of 1a with 2-cyanopyrdine was carried out at À608C for 3 h
in the presence of HMPA, 1a was converted to 2i and 8a.
Although the yield of 2i increased with increasing reaction
temperature, the amount of 8a remained almost unchanged
between À130 and 358C. On the basis of these observations,
the reaction mechanisms shown in Scheme 3 are proposed.
To gain insights into the mechanism of pyridine forma-
tion, 1a was allowed to react with 2-cyanopyrdine from
À130 to 358C in Et2O (Table 4). A mixture of pyridine 2i
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Reactions of 1,4-Dilithio-1,3-dienes with Nitriles
FULL PAPER
Table 4. Formation of pyridine 2i and cyclopentadienyl amine 8a.
a-hydrogen atoms such as butyronitrile and acrylonitrile
were not suitable for the present reaction, presumably due
to rapid proton abstraction by the dilithium compounds.[12]
The reaction of trimethylacetonitrile with dilithium com-
pound 5 f having a five-membered ring in the 2,3-positions
gave tricyclic D1-bipyrroline 9d in 64% yield (Table 5,
entry 4). Besides aliphatic nitriles without a-hydrogen
atoms, a wide range of aromatic nitriles was suitable for the
formation of tricyclic D1-bipyrrolines. The reaction was not
affected by electron-withdrawing or -donating substituents
or their positions on the phenyl ring of an aromatic nitrile
T [8C]
t [h]
Yield of
Yield of
Yield of
2i [%][a]
8a [%][a]
4a [%][a]
À130
À130
À78
À78
À60
À60
À30
0
1
3
1
3
1
3
1
1
1
1
39
40
50
61
67
66
70
71
73
72
19
21
23
20
16
23
17
20
18
21
25
20
14
9
À
(Table 5, entries 5–13). The aromatic C Br bond could sur-
5
0
0
0
0
0
vive under the present reaction conditions. Traces of pyri-
dine derivatives were observed in some cases by gas chro-
matographic monitoring when aromatic nitriles were used.
The reactions in entries 1–4 of Table 5 involving aliphatic ni-
triles without a-hydrogen atoms gave similar yields of prod-
ucts with or without HMPA. In the other cases listed in
Table 5, good to high yields of products could be obtained
in the presence of HMPA, but without HMPA messy mix-
tures of products were obtained. In contrast to the synthesis
of pyridines (Tables 2 and 3), 2.4 rather than 4 equivalents
of organonitrile were used, because self-cyclotrimerization
of nitriles did not occur. No triazine derivatives were ob-
served.
20
35
[a] Determined by GC.
2-Cyanopyridine was not suitable for the formation of a
tricyclic D1-bipyrroline. Conversely, the reaction of 2-cyano-
pyridine with dilithio reagent 5c gave exclusively pyridine
6 f (Table 3, entry 6). Although the reaction of five- and six-
membered-ring fused dilithio reagents with nitriles gave tri-
cyclic D1-bipyrrolines (Table 5), seven-membered-ring fused
dilithium compound 5d reacted with PhCN or trimethylace-
tonitrile to afford the corresponding pyridines in good yield
(Table 3, entries 7 and 8). All results for the formation of tri-
cyclic D1-bipyrrolines show that both the substituents in the
1,4-positions and the size of the fused ring in 1,4-dilithio-1,3-
diene play an important role in determining the structure of
the products.
Scheme 3. Proposed mechanisms for the formation of pyridines.
Development of synthetically useful methods for N-con-
taining heterocycles, especially those with new central skele-
tons, has continuously been an attractive research topic in
synthetic chemistry, since they have diverse applications in
many areas. This work provides a very convenient and high-
yield method for the synthesis of unprecedented tricyclic D1-
pyrroline derivatives. Interesting applications of this new
type of D1-pyrroline derivatives can be expected.
Addition of one lithium alkenyl bond to the nitrile gives the
N-lithio ketimine, which undergoes 5-exo cyclization to
afford the cyclopentadienyl amine via hydrolysis of the di-
lithium cyclopentadienyl amide. The intermediate N-lithio
ketimine reacts further with another equivalent of nitrile to
give dilithio bis-ketimine. Then 6-endo cyclization followed
by elimination of C,N-dilithioaldehyde imine yields a pyri-
dine derivative.
An X-ray analysis of 9e revealed that two D1-pyrroline
À
rings and one cyclohexyl ring share one C C single bond
(Figure 1).
Formation of tricyclic D1-bipyrrolines: The reaction of
Type II dilithium reagents with trimethylacetonitrile yielded
a mixture of pyridines and unexpected D1-bipyrrolines
(Scheme 2). However, cyclic dilithio reagent 5c (Type III)
reacted with trimethylacetonitrile to afford exclusively tricy-
clic D1-bipyrroline 9a in 90% yield (Table 5, entry 1). Simi-
larly, 9b,c were easily prepared by reaction of 5c with 2-
ethyl-2-methylbutanenitrile and 1-adamantanecarbonitrile,
respectively (Table 5, entries 2 and 3). Aliphatic nitriles with
A proposed mechanism for the formation of tricyclic D1-
bipyrrolines is shown in Scheme 4. Intermolecular nucleo-
philic addition of 5c to nitriles initially affords dilithio bis-
ketimines 10. The subsequent double 5-exo lithiation/cycliza-
tion of 10 proceeds in an intramolecular manner to give tri-
cyclic D1-bipyrroline 9 via protonolysis of 1-azaallylic dia-
nion 11.[16] Deuterated tricyclic D1-bipyrroline 9aD was iso-
lated in 85% yield with slightly less than two deuterium
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Z. Xi et al.
Table 5. Reaction of 2,3-disubstituted cyclic 1,4-dilithio-1,3-dienes with nitriles.
D2O (20 wt%). Attempts to
isolate intermediate 10 or dia-
nion 11 failed.
Formation of siloles and (Z,Z)-
dienylsilanes: The reaction of
1,2,3,4-tetrapropyl-1,4-dilithio-
1,3-diene 1a (Type I) with
Me3SiCN yielded silole 12a in-
stead of the pyridine via cleav-
Entry
Nitrile
Pyrroline 9
Isolated product
(yield [%])
1
2
9a (90)[a]
9b (81)[a]
À
age of the Si C bond of
Me3SiCN. Similarly, the reac-
tion of cyclic tetrasubstituted
dilithio
reagent
1b
with
Me3SiCN afforded silole 12b.
We recently reported that lith-
iation of 1-bromo-4-trisubstitut-
ed silyl-1,3-butadiene deriva-
tives with tBuLi gave substitut-
ed siloles in high yields.[17] We
also described the facile synthe-
sis of lithio siloles from silyl
1,4-dilithio-1,3-butadiene deriv-
atives.[18] By using Me3SiCN,
both silylation and intramolecu-
lar nucleophilic substitution can
be achieved in a one-pot proce-
3
9c (95)[a]
4
5
9d (64)[a]
9e (54)
6
9 f (53)
9g (57)
9h (52)
9i (60)
9j (70)
9k (55)
dure
to
prepare
siloles
7
(Scheme 5). This reaction is an
alternative convenient method
for the preparation of multiply
substituted siloles from 1,4-dili-
thio-1,3-dienes.
8
When 2,3-disubstituted 1,4-
dilithio-1,3-dienes 5 were treat-
ed with Me3SiCN, an interesting
double silylation reaction took
place to afford (Z,Z)-dienylsi-
lanes 13 with perfect stereose-
lectivity (Scheme 6).[15g] To the
best of our knowledge, synthe-
sis of (Z,Z)-dienylsilanes has
remained unexplored, although
(E,E)-dienylsilanes were pre-
pared previously by cyclization
of silyl-capped terminal diynes
mediated by low-valent organo-
metallic compounds of Group 4
metals.[15,19]
9
10
11
12
9l (56)
13
9m (55)
Conclusion
[a] Without HMPA.
In summary, we have demon-
strated diverse reactions of 1,4-
atoms in the methylene positions (endo:exo=2: 3) when the
tBu-substituted 1-azaallylic dianion was quenched with DCl/
dilithio-1,3-dienes with nitriles. Pyridines, tricyclic D1-bipyr-
rolines, siloles, and (Z,Z)-dienylsilanes can be readily pre-
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Reactions of 1,4-Dilithio-1,3-dienes with Nitriles
FULL PAPER
Scheme 6. Reaction of 2,3-disubstituted 1,4-dilithio-1,3-dienes with
Me3SiCN.
pared in good yields by using appropriate combination of di-
lithio reagents and nitriles. 1,2,3,4-Tetrasubstituted (Type I)
and 2,3-disubstituted dilithio reagents (Type II) react with
aromatic nitriles to provide pyridines in good yields. When
ring-fused dilithio reagents (Type III) reacted with aromatic
nitriles or aliphatic nitriles without a-hydrogen atoms, tricy-
clic D1-bipyrrolines were predominately formed. When tet-
rasubstituted dilithio reagents (Type I) were treated with
Me3SiCN, a tandem silylation/intramolecular substitution
process readily occurred to yield siloles, while the reaction
of 2,3-disubstituted dilithio reagents (Types II and III) with
Me3SiCN gave (Z,Z)-dienylsilanes with high stereoselectiv-
ity. These results reveal that the outcome of the reaction is
strongly dependent on the structure of the dilithio reagents
and the nature of the nitriles. Further investigations into ap-
plications of the novel tricyclic D1-bipyrrolines are under-
way.
Figure 1. ORTEP drawing of one enantiomer of 9e with 30% thermal el-
lipsoids. Hydrogen atoms are omitted for clarity. Selected bond lengths
À
À
À
[Š] and angles [8]: N3 C38 1.293(3), C37 C38 1.516(3), C23 C37
À
À
À
À
1.524(3), C23 C28 1.545(3), N3 C28 1.496(3), N4 C30 1.285(2), C29
À
À
À
C30 1.509(3), C28 C29 1.535(3), C23 C28 1.545(3), N4 C23 1.492(3);
C28-N3-C38 108.55(19), N3-C38-C37 114.9(2), C23-N4-C30 109.14(18),
N4-C30-C29 114.6(2).
Experimental Section
General: All reactions were conducted under a slightly positive pressure
of dry, prepurified nitrogen by using standard Schlenk line techniques
where appropriate. Unless otherwise noted, all starting materials were
commercially available and were used without further purification. Di-
ethyl ether was refluxed and distilled from sodium benzophenone ketyl
under a nitrogen atmosphere. All organolithium reagents were obtained
from Acros Organics. All the butadienyl iodides were synthesized by the
reported procedure. All yields refer to isolated products.[15]
Scheme 4. Proposed mechanism for the formation of the tricyclic D1-bi-
pyrrolines.
1H and 13C NMR spectra were recorded at 300 and 75.4 MHz, respective-
ly, in CDCl3 solution containing 0.1% TMS on a JEOLJNM-AL300
NMR spectrometer.
CCDC-240170 (9e) contains the supplementary crystallographic data for
this paper. These data can be obtained free of charge from The Cam-
bridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_
request/cif.
Typical procedure for the preparation of pyridines 2 from 1,2,3,4-tetra-
substituted 1,4-diiodo-1,3-dienes: tBuLi (4.0 mmol, 1.5m in pentane) was
added to
a solution of 1,2,3,4-tetrasubstituted 1,4-diiodo-1,3-diene
(1.0 mmol) in diethyl ether (5 mL) at À788C. The reaction mixture was
then stirred at À788C for 1 h to generate 1,4-dilithio-1,3-diene 1, which
was monitored by GC analysis or by TLC. HMPA (2.0 mmol) was then
added, and the reaction mixture was stirred at room temperature for
0.5 h. After addition of nitrile (4.0 mmol), the mixture was stirred at
room temperature for 3 h. The reaction mixture was then quenched with
saturated aqueous NaHCO3 and extracted with diethyl ether. The extract
was washed with brine and dried over MgSO4. The solvent was evaporat-
Scheme 5. Reaction of 1,2,3,4-tetrasubstituted 1,4-dilithio-1,3-dienes with
Me3SiCN.
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5675

Z. Xi et al.
ed in vacuo to give a yellow oil, which was purified by column chroma-
tography (neutral Al2O3, hexane/Et2O=4:1) to afford pyridines 2a–j.
125.2, 125.5, 125.8, 126.0, 126.5, 127.7, 128.1, 132.3, 132.5, 132.7, 133.8,
139.6, 148.3, 155.2, 157.4 ppm; HRMS calcd for C27H35N: 373.2770,
found: 373.2768.
1
2a: Light yellow liquid, 62% yield (200 mg); H NMR (300 MHz, CDCl3,
1
TMS, 258C): d=0.78 (t, J=7.2 Hz, 3H), 1.00 (t, J=7.2 Hz, 3H), 1.03–
1.20 (m, 6H), 1.31–1.42 (m, 2H), 1.48–1.64 (m, 4H), 1.68–1.81 (m, 2H),
2.47 (t, J=8.1 Hz, 2H), 2.54–2.69 (m, 4H), 2.74 (t, J=7.5 Hz, 2H), 7.23–
7.60 ppm (m, 5H); 13C NMR (75 MHz, CDCl3, TMS, 258C): d=14.4,
14.6, 14.9, 15.0, 23.7, 24.5, 24.6, 31.0, 31.4, 31.5, 37.5, 127.1, 128.0, 128.9,
131.2, 132.4, 142.4, 148.2, 156.5, 157.1 ppm; HRMS calcd for C23H33N:
323.2613, found: 323.2604.
2i: Light yellow liquid, 55% yield (178 mg); H NMR (300 MHz, CDCl3,
TMS, 258C): d=0.78 (t, J=7.2 Hz, 3H), 1.00 (t, J=7.2 Hz, 3H), 1.04–
1.12 (m, 6H), 1.35–1.41 (m, 2H), 1.47–1.63 (m, 4H), 1.69–1.79 (m, 2H),
2.57–2.80 (m, 8H), 7.20–7.28 (m, 1H), 7.54–7.61 (m, 1H), 7.71–7.79 (m,
1H), 8.59–8.65 ppm (m, 1H); 13C NMR (75 MHz, CDCl3, TMS, 258C):
d=14.4, 14.6, 14.9, 15.0, 23.5, 24.4, 24.5, 29.7, 30.6, 31.0, 31.3, 37.4, 122.1,
124.4, 132.0, 133.4, 136.4, 148.3, 148.7, 154.2, 157.1, 160.6 ppm; HRMS
calcd for C22H32N2: 324.2566, found: 324.2570.
1
2b: Light yellow liquid, 63% yield (212 mg); H NMR (300 MHz, CDCl3,
1
2j: Light yellow liquid, 73% yield (234 mg); H NMR (300 MHz, CDCl3,
TMS, 258C): d=0.79 (t, J=7.2 Hz, 3H), 0.99 (t, J=7.2 Hz, 3H), 1.03–
1.12 (m, 6H), 1.32–1.41 (m, 2H), 1.49–1.62 (m, 4H), 1.67–1.78 (m, 2H),
2.38 (s, 3H), 2.48 (t, J=8.1 Hz, 2H), 2.53–2.66 (m, 4H), 2.73 (t, J=
8.1 Hz, 2H), 7.18 (d, J=7.8 Hz, 2H), 7.18 ppm (d, J=8.1 Hz, 2H);
13C NMR (75 MHz, CDCl3, TMS, 258C): d=14.43, 14.57, 14.90, 15.02,
21.25, 23.65, 24.53, 24.58, 24.62, 30.98, 31.43, 31.48, 37.41, 128.62, 128.77,
131.24, 132.19, 136.66, 139.53, 148.18, 156.52, 157.08 ppm; HRMS calcd
for C24H35N: 337.2770, found: 337.2755.
TMS, 258C): d=0.76 (t, J=6.9 Hz, 3H), 0.93 (t, J=7.2 Hz, 3H), 1.16–
1.26 (m, 2H), 1.29–1.51 (m, 4H), 1.59–1.72 (m, 2H), 1.76–1.94 (m, 4H),
2.47 (t, J=7.5 Hz, 2H), 2.62–2.97 (m, 6H), 7.21–7.49 ppm (m, 5H);
13C NMR (75 MHz, CDCl3, TMS, 258C): d=13.6, 14.1, 22.6, 23.0, 23.1,
26.0, 26.6, 28.4, 31.4, 32.0, 35.1, 127.1, 128.0, 128.8, 129.0, 131.2, 142.2,
144.6, 155.5, 157.3 ppm; HRMS calcd for C23H31N: 321.2457, found:
321.2455.
1
Typical procedure for the preparation of pyridines 6a–h from 2,3-disub-
stituted 1,4-diiodo-1,3-dienes: tBuLi (4.0 mmol, 1.5m in pentane) was
added to a solution of 2,3-disubstituted 1,4-diiodo-1,3-diene (1.0 mmol)
in diethyl ether (5 mL) at À788C. The reaction mixture was then stirred
at À788C for 1 h to generate 1,4-dilithio-1,3-diene 5, which was moni-
tored by GC analysis or by TLC. HMPA (2.0 mmol) was then added, and
the reaction mixture was stirred at room temperature for 0.5 h. After ad-
dition of nitrile (4.0 mmol), the mixture was stirred at room temperature
for 3 h. The reaction mixture was then quenched with saturated aqueous
NaHCO3 and extracted with diethyl ether. The extract was washed with
brine and dried over MgSO4. The solvent was evaporated in vacuo to
give a yellow oil, which was purified by column chromatography (neutral
Al2O3, hexane/Et2O=4:1) to afford pyridines 6a–h.
2c: Light yellow liquid, 80% yield (282 mg); H NMR (300 MHz, CDCl3,
TMS, 258C): d=0.79 (t, J=7.2 Hz, 3H), 0.98 (t, J=7.2 Hz, 3H), 1.03–
1.13 (m, 6H), 1.32–1.44 (m, 2H), 1.49–1.62 (m, 4H), 1.67–1.80 (m, 2H),
2.44–2.54 (m, 2H), 2.55–2.68 (m, 4H), 2.69–2.79 (m, 2H), 3.82 (s, 3H),
6.92 (d, J=8.4 Hz, 2H), 7.32 ppm (d, J=8.4 Hz, 2H); 13C NMR
(75 MHz, CDCl3, TMS, 258C): d=14.4, 14.6, 14.9, 15.0, 23.6, 24.5, 24.6,
31.0, 31.47, 31.51, 31.6, 37.5, 55.3, 113.4, 130.1, 131.3, 132.1, 135.2, 148.2,
156.2, 157.1, 158.8 ppm; HRMS calcd for C24H35NO: 353.2719, found:
353.2729.
1
2d: Light yellow liquid, 60% yield (202 mg); H NMR (300 MHz, CDCl3,
TMS, 258C): d=0.79 (t, J=7.2 Hz, 3H), 0.97–1.10 (m, 9H), 1.34–1.40 (m,
2H), 1.51–1.61 (m, 4H), 1.69–1.77 (m, 2H), 2.37 (s, 3H), 2.44–2.49 (m,
2H), 2.57–2.63 (m, 4H), 2.72–2.77 (m, 2H), 7.12–7.26 ppm (m, 4H);
13C NMR (75 MHz, CDCl3, TMS, 258C): d=14.4, 14.6, 14.91, 15.0, 21.5,
23.8, 24.5, 24.60, 24.63, 31.0, 31.4, 31.5, 37.5, 125.8, 127.8, 127.9, 129.7,
131.2, 132.2, 137.4, 142.3, 148.2, 156.7, 157.1 ppm; HRMS calcd for
C24H35N: 337.2770, found: 337.2782.
1
6a: Light yellow liquid, 60% yield (194 mg); H NMR (300 MHz, CDCl3,
TMS, 258C): d=0.88–0.92 (m, 6H), 1.32–1.67 (m, 16H), 2.60–2.62 (m,
4H), 7.24–7.49 (m, 4H), 7.94–7.98 (m, 2H), 8.42 ppm (s, 1H); 13C NMR
(75 MHz, CDCl3, TMS, 258C): d=14.1, 22.61, 22.64, 29.3, 29.4, 29.8, 30.4,
31.0, 31.7, 32.2, 120.7, 126.7, 128.4, 128.6, 134.6, 139.7, 150.0, 150.3,
155.0 ppm. The NMR data are consistent with the reported data.[7b]
1
2e: Light yellow liquid, 53% yield (213 mg); H NMR (300 MHz, CDCl3,
TMS, 258C): d=0.81 (t, J=7.2 Hz, 3H), 0.98–1.10 (m, 9H), 1.35–1.38 (m,
2H), 1.50–1.60 (m, 4H), 1.71–1.73 (m, 2H), 2.43–2.48 (m, 2H), 2.57–2.62
(m, 4H), 2.71–2.76 (m, 2H), 7.26–7.55 ppm (m, 4H); 13C NMR (75 MHz,
CDCl3, TMS, 258C): d=14.4, 14.5, 14.9, 15.0, 23.7, 24.51, 24.53, 24.6, 31.0,
31.3, 31.4, 37.4, 122.2, 127.6, 129.5, 130.3, 131.2, 132.1, 132.9, 144.4, 148.5,
154.9, 157.4 ppm; HRMS calcd for C23H32N79Br: 401.1718, found:
401.1723.
1
6b: Light yellow liquid, 59% yield (199 mg); H NMR (300 MHz, CDCl3,
TMS, 258C): d=0.87–0.92 (m, 6H), 1.32–1.67 (m, 16H), 2.37 (s, 3H),
2.59–2.65 (m, 4H), 7.23–7.25 (m, 2H), 7.46 (s, 1H), 7.85–7.88 (m, 2H),
8.39 ppm (s, 1H); 13C NMR (75 MHz, CDCl3, TMS, 258C): d=14.1, 21.2,
22.6, 22.6, 29.3, 29.4, 29.8, 30.4, 31.1, 31.7, 32.2, 120.3, 126.5, 129.3, 134.3,
136.9, 138.3, 149.9, 150.2, 155.0 ppm. The NMR data are consistent with
the reported data.[7b]
1
2 f: Light yellow liquid, 58% yield (231 mg); H NMR (300 MHz, CDCl3,
1
6c: Light yellow liquid, 57% yield (175 mg); H NMR (300 MHz, CDCl3,
TMS, 258C): d=0.82 (t, J=7.2 Hz, 3H), 1.01–1.11 (m, 9H), 1.39–1.47 (m,
TMS, 258C): d=7.16–7.28 (m, 10H), 7.41–7.50 (m, 3H), 7.76 (s, 1H),
8.06 (d, J=3.6 Hz, 2H), 8.72 ppm (s, 1H); 13C NMR (75 MHz, CDCl3,
TMS, 258C): d=121.5, 126.9, 127.2, 127.8, 128.2, 128.3, 128.8, 129.0,
129.3, 129.8, 134.2, 137.6, 139.0, 148.5, 150.9, 156.4 ppm; HRMS calcd for
C23H17N: 307.1361, found: 307.1352.
2H), 1.52–1.62 (m, 4H), 1.72–1.80 (m, 2H), 2.25–2.45 (m, 2H), 2.52–2.64-
A
13C NMR (75 MHz, CDCl3, TMS, 258C): d=14.5, 14.6, 14.9, 15.0, 23.7,
24.5, 24.6, 24.7, 31.0, 31.44, 31.5, 37.5, 126.8, 127.1, 128.7, 129.3, 131.3,
132.4, 139.9, 141.2, 141.5, 148.3, 156.1, 157.3 ppm; HRMS calcd for
C29H37N: 399.2926, found: 399.2939.
1
6d: Light yellow liquid, 86% yield (279 mg); H NMR (300 MHz, CDCl3,
1
TMS, 258C): d=0.87–0.92 (m, 6H), 1.26–1.71 (m, 16H), 2.64–2.71 (m,
4H), 7.24–7.28 (m, 1H), 7.75–7.81 (m, 1H), 8.18 (brs, 1H), 8.35–8.41 (m,
2H), 8.65–8.68 ppm (m, 1H); 13C NMR (75 MHz, CDCl3, TMS, 258C):
d=14.1, 22.60, 22.62, 29.3, 29.5, 30.0, 30.5, 31.0, 31.7, 32.3, 120.8, 121.1,
123.3, 136.5, 136.8, 149.1, 150.0, 150.5, 153.7, 156.6 ppm. The NMR data
are consistent with the reported data.[7b]
6e: Light yellow solid, 60% yield (185 mg); m.p. 123–1248C;; 1H NMR
(300 MHz, CDCl3, TMS, 258C): d=7.18–7.30 (m, 11H), 7.77–7.83 (m,
1H), 8.46–8.49 (m, 2H), 8.67–8.71 ppm (m, 2H); 13C NMR (75 MHz,
CDCl3, TMS, 258C): d=121.1, 122.1, 127.3, 127.8, 128.2, 128.3, 129.4,
129.8, 135.7, 136.9, 137.6, 138.8, 148.7, 149.2, 150.5, 155.1, 155.9 ppm;
HRMS calcd for C22H16N2: 308.1314, found: 308.1308.
2g: Light yellow liquid, 55% yield (227 mg); H NMR (300 MHz, CDCl3,
TMS, 258C): d=0.65 (t, J=7.2 Hz, 3H), 0.84 (t, J=7.2 Hz, 3H), 0.94 (t,
J=7.2 Hz, 3H), 1.04 (t, J=7.2 Hz, 3H), 1.11–1.19 (m, 4H), 1.50–1.54 (m,
2H), 1.64–1.67 (m, 2H), 1.99–2.04 (m, 2H), 2.22 (s, 3H), 2.39–2.42 (m,
2H), 2.46–2.56 (m, 2H), 2.75 (brs, 2H), 6.87–6.96 (m, 4H), 7.39 ppm (s,
4H); 13C NMR (75 MHz, CDCl3, TMS, 258C): d=14.1, 14.4, 14.5, 14.7,
20.9, 23.9, 24.0, 24.1, 24.7, 30.8, 30.9, 31.2, 37.2, 127.0, 127.7, 128.1, 129.27,
129.31, 130.0, 131.9, 132.1, 135.7, 138.5, 140.7, 140.8, 147.8, 156.1,
156.7 ppm; HRMS calcd for C30H39N: 413.3083, found: 413.3093.
1
2h: Light yellow liquid, 57% yield (213 mg); H NMR (300 MHz, CDCl3,
TMS, 258C): d=0.60 (t, J=7.2 Hz, 3H), 0.98 (t, J=7.2 Hz, 3H), 1.06–
1.14 (m, 6H), 1.20–1.27 (m, 2H), 1.56–1.75 (m, 6H), 2.06–2.16 (m, 1H),
2.35–2.45 (m, 1H), 2.61–2.69 (m, 4H), 2.74–2.79 (m, 2H), 7.32–7.50 (m,
5H), 7.82–7.86 ppm (m, 2H); 13C NMR (75 MHz, CDCl3, TMS, 258C):
d=14.4, 14.6, 14.9, 15.0, 24.0, 24.62, 24.63, 24.7, 31.1, 31.5, 31.8, 37.5,
6 f: Orange liquid, 58% yield (122 mg); 1H NMR (300 MHz, CDCl3,
TMS, 258C): d=1.77–1.79 (m, 4H), 2.73–2.79 (m, 4H), 7.19–8.64 ppm
(m, 6H); 13C NMR (75 MHz, CDCl3, TMS, 258C): d=22.2, 22.4, 26.0,
5676
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Chem. Eur. J. 2008, 14, 5670 – 5679

Reactions of 1,4-Dilithio-1,3-dienes with Nitriles
FULL PAPER
28.7, 120.6, 120.9, 123.0, 133.2, 136.6, 146.8, 148.8, 149.7, 152.7,
156.3 ppm; HRMS calcd for C14H14N2: 210.1152, found: 210.1157.
2.30 (d, J=6.0 Hz, 2H), 2.66 (d, J=17.1 Hz, 2H), 2.96 ppm (d, J=
17.1 Hz, 2H); 13C NMR (75 MHz, CDCl3, TMS, 258C): d=20.9, 27.8,
32.6, 35.3, 43.0, 78.8, 181.0 ppm; HRMS calcd for C18H30N2: 274.2409,
found: 274.2402.
9aD: White solid, 85% yield (235 mg); m.p. 92–938C; 1H NMR
(300 MHz, CDCl3, TMS, 258C): d=1.09 (brs, 18H, CH3; 4H, CH2), 1.61–
1.64 (m, 2H), 2.29 (d, J=6.0 Hz, 2H), 2.66 (brs, 0.8H, endo), 2.96 ppm
(brs, 1.2H, exo); 13C NMR (75 MHz, CDCl3, TMS, 258C): d=21.0, 27.8,
32.6, 35.3, 42.66, 42.92, 43.18 (JCD =19.5 Hz), 78.8, 181.1 ppm; HRMS
calcd for C18H28N2D2: 276.2534, found: 276.2535.
9b: Colorless liquid, 81% yield (267 mg); 1H NMR (300 MHz, CDCl3,
TMS, 258C): d=0.70–1.62( m, 18H, CH3; 14H, CH2), 2.34 (d, J=6.0 Hz,
2H), 2.60 (d, J=17.1 Hz, 2H), 2.97 ppm (d, J=17.1 Hz, 2H); 13C NMR
(75 MHz, CDCl3, TMS, 258C): d=8.6, 8.7, 20.9, 21.2, 31.9, 32.1, 33.5,
42.3, 43.6, 78.9, 179.8 ppm; HRMS calcd for C22H38N2: 330.3035, found:
330.3040.
9c: White solid, 95% yield (409 mg); m.p. 222–2238C; 1H NMR
(300 MHz, CDCl3, TMS, 258C): d=0.94–2.04 (m, 6H, CH; 30H, CH2),
2.27 (d, J=6.0 Hz, 2H), 2.59 (d, J=17.1 Hz, 2H), 2.94 ppm (d, J=
17.1 Hz, 2H); 13C NMR (75 MHz, CDCl3, TMS, 258C): d=20.9, 28.0,
32.8, 36.6, 37.3, 40.0, 42.5, 78.1, 181.9 ppm; HRMS calcd for C30H42N2:
430.3348, found: 430.3350.
9d: Orange liquid, 64% yield (166 mg); 1H NMR (300 MHz, CDCl3,
TMS, 258C): d=1.14 (s, 18H), 1.51–1.59 (m, 2H), 1.80–1.96 (m, 4H),
2.71(d, J=18.3 Hz, 2H), 2.83 ppm (d, J=18.3 Hz, 2H); 13C NMR
(75 MHz, CDCl3, TMS, 258C): d=24.8, 28.3, 35.6, 40.0, 47.0, 91.7,
182.3 ppm; HRMS calcd for C17H38N2: 260.2252, found: 260.2244.
9e: White solid, 54% yield (170 mg); m.p. 182–1838C; 1H NMR
(300 MHz, CDCl3, TMS, 258C): d=1.21–1.31 (m, 4H), 1.70–1.72 (m,
2H), 2.44–2.48 (m, 2H), 3.20 (d, J=17.1 Hz, 2H), 3.53 (d, J=17.1 Hz,
2H), 7.33–7.40 (m, 6H), 7.78–7.81 ppm (m, 4H); 13C NMR (75 MHz,
CDCl3, TMS, 258C): d=20.8, 33.0, 45.2, 80.3, 127.7, 128.3, 130.5, 134.5,
169.5 ppm; HRMS calcd for C22H22N2: 314.1783, found: 314.1779.
9 f: White solid, 53% yield (198 mg); m.p. 165–1668C; 1H NMR
(300 MHz, CDCl3, TMS, 258C): d=1.28 (brs, 4H), 1.68 (brs, 2H), 2.41–
2.44 (m, 2H), 3.14 (d, J=17.1 Hz, 2H), 3.48(d, J=17.1 Hz, 2H), 3.80 (s,
6H), 6.87 (d, J=7.0 Hz, 4H), 7.74 ppm (d, J=7.1 Hz, 4H); 13C NMR
(75 MHz, CDCl3, TMS, 258C): d=20.8, 33.1, 45.3, 55.3, 80.1, 113.7, 127.4,
129.4, 161.5, 168.9 ppm; HRMS calcd for C24H26N2O2: 374.1994, found:
374.2003.
9g: White solid, 57% yield (195 mg); m.p. 122–1238C; 1H NMR
(300 MHz, CDCl3, TMS, 258C): d=1.21–1.37 (m, 4H), 1.72 (brs, 2H),
2.44 (brs, 6H, CH3; 2H, CH2), 3.22 (d, J=17.9 Hz, 2H) , 3.39 (d, J=
17.9 Hz, 2H), 7.18–7.25 (m, 6H), 7.35–7.37 ppm (m, 2H); 13C NMR
(75 MHz, CDCl3, TMS, 258C): d=20.1, 32.9, 48.5, 80.6, 125.6, 128.3,
129.0, 131.0, 135.3, 136.5, 172.1 ppm; HRMS calcd for C24H26N2:
342.2096, found: 342.2102.
6g: Orange liquid, 56% yield (125 mg); 1H NMR (300 MHz, CDCl3,
TMS, 258C): d=1.63 (brs, 4H), 1.82–1.84 (m, 2H), 2.75–2.80 (m, 4H),
7.34–7.44 (m, 4H), 7.93–7.97 (m, 2H), 8.36 ppm (s, 1H); 13C NMR
(75 MHz, CDCl3, TMS, 258C): d=27.6, 28.0, 32.6, 32.9, 36.5, 120.7, 126.7,
128.4, 128.6, 137.2, 139.6, 149.2, 152.7, 155.6 ppm; HRMS calcd for
C16H17N: 223.1361, found: 223.1351.
6h: Orange solid, 60% yield (122 mg); m.p. 91–928C; 1H NMR
(300 MHz, CDCl3, TMS, 258C): d=1.35 (s, 9H), 1.61–1.65 (m, 4H), 1.81–
1.86 (m, 2H), 2.72–2.76 (m, 4H), 7.04 (s, 1H), 8.24 ppm (s, 1H);
13C NMR (75 MHz, CDCl3, TMS, 258C): d=27.7, 28.1, 30.3, 32.7, 32.9,
36.7, 36.8, 119.2, 135.3, 148.1, 152.0, 167.2 ppm; HRMS calcd for
C14H21N: 203.1674, found: 203.1670.
Typical procedure for the preparation of pyridines 6i,j and D1-bipyrro-
lines 7a,b from 2,3-disubstituted 1,4-diiodo-1,3-dienes: tBuLi (4.0 mmol,
1.5m in pentane) was added to a solution of 2,3-disubstituted 1,4-diiodo-
1,3-diene (1.0 mmol) in diethyl ether (5 mL) at À788C. The reaction mix-
ture was then stirred at À788C for 1 h to generate 1,4-dilithio-1,3-diene
5, which was monitored by GC analysis or by TLC. HMPA (2.0 mmol)
was then added, and the reaction mixture was stirred at room tempera-
ture for 0.5 h. After addition of nitrile (4.0 mmol), the mixture was
stirred at room temperature for 3 h. The reaction mixture was then
quenched with saturated aqueous NaHCO3 and extracted with diethyl
ether. The extract was washed with brine and dried over MgSO4. The sol-
vent was evaporated in vacuo to give a yellow oil, which was purified by
column chromatography (neutral Al2O3, hexane/Et2O=4:1) to afford
pyridines 6i,j and D1-bipyrrolines 7a,b.
6i: Light yellow liquid, 29% yield (88 mg); 1H NMR (300 MHz, CDCl3,
TMS, 258C): d=0.88–0.92 (m, 6H), 1.29–1.43 (m, 9H, CH3; 12H, CH2),
1.51–1.62 (m, 4H), 2.54–2.60 (m, 4H), 7.07 (s, 1H), 8.28 ppm (s, 1H);
13C NMR (75 MHz, CDCl3, TMS, 258C): d=14.0, 14.1, 22.6, 29.3, 29.4,
29.7, 30.3, 30.5, 31.0, 31.6, 31.7, 32.3, 36.8, 119.1, 132.7, 149.1, 149.3,
166.5 ppm; HRMS calcd for C21H37N: 303.2926, found: 303.2932.
6j: Light yellow liquid, 22% yield (54 mg); 1H NMR (300 MHz, CDCl3,
TMS, 258C): d=0.92–0.99 (m, 6H), 1.35 (s, 9H), 1.40–1.45 (m, 4H),
1.47–1.61 (m, 4H), 2.55–2.60 (m, 4H), 7.08 (s, 1H), 8.28 ppm (s, 1H);
13C NMR (75 MHz, CDCl3, TMS, 258C): d=13.9, 14.0, 22.7, 22.8, 29.3,
30.3, 32.0, 32.7, 33.2, 36.8, 119.1, 132.7, 149.1, 149.3, 166.5 ppm; HRMS
calcd for C17H29N: 247.2300, found: 247.2302.
1
7a: Light yellow liquid, 34% yield (132 mg); H NMR (300 MHz, CDCl3,
TMS, 258C): d=0.88 (t, J=7.5 Hz, 6H), 1.08 (s, 18H), 1.27–1.77 (m,
20H), 2.50 (d, J=17.1 Hz, 2H), 2.99 ppm (d, J=17.1 Hz, 2H); 13C NMR
(75 MHz, CDCl3, TMS, 258C): d=14.1, 22.6, 25.1, 28.1, 30.1, 31.7, 35.2,
35.6, 45.9, 83.5, 181.1 ppm; HRMS calcd for C26H48N2: 388.3818, found:
388.3826.
1
7b: Light yellow liquid, 30% yield (100 mg); H NMR (300 MHz, CDCl3,
TMS, 258C): d=0.89 (t, J=7.8 Hz, 6H), 1.09 (s, 18H), 1.27–1.77 (m,
12H), 2.50 (d, J=17.1 Hz, 2H), 2.99 ppm (d, J=17.1 Hz, 2H); 13C NMR
(75 MHz, CDCl3, TMS, 258C): d=14.0, 23.5, 27.4, 28.1, 34.9, 35.6, 45.9,
83.5, 181.2 ppm; HRMS calcd for C22H40N2: 332.3192, found: 332.3198.
9h: White solid, 52% yield (178 mg); m.p. 167–1688C; 1H NMR
(300 MHz, CDCl3, TMS, 258C): d=1.27 (brs, 4H), 1.68 (brs, 2H), 2.33(s,
E
6H), 2.38–2.46 (m, 2H), 3.18 (d, J=17.3 Hz, 2H), 3.51 (d, J=17.3 Hz,
2H), 7.16–7.26 (m, 4H), 7.52–7.55 (m, 2H), 7.66 ppm (s, 2H); 13C NMR
(75 MHz, CDCl3, TMS, 258C): d=20.8, 21.2, 33.0, 45.3, 80.3, 125.1, 128.1,
128.2, 131.2, 134.5, 138.0, 169.6 ppm; HRMS calcd for C24H26N2:
342.2096, found: 342.2090.
9i: White solid, 60% yield (205 mg); m.p. 190–1918C; 1H NMR
(300 MHz, CDCl3, TMS, 258C): d=1.28 (brs, 4H), 1.68 (brs, 2H), 2.34
(s, 6H), 2.43–2.46 (m, 2H), 3.17 (d, J=17.1 Hz, 2H), 3.50 (d, J=17.1 Hz,
2H), 7.16 (d, J=3.6 Hz, 4H), 7.68 ppm (d, J=3.8 Hz, 4H); 13C NMR
(75 MHz, CDCl3, TMS, 258C): d=20.9, 21.4, 33.1, 45.3, 80.2, 127.7, 129.0,
131.9, 140.6, 169.4 ppm; HRMS calcd for C24H26N2: 342.2096, found:
342.2090.
9j: White solid, 70% yield (329 mg); m.p. 163–1648C; 1H NMR
(300 MHz, CDCl3, TMS, 258C): d=1.18–1.32 (m, 4H), 1.69 (brs, 2H),
2.43–2.46 (m, 2H), 3.17 (d, J=17.1 Hz, 2H), 3.47 (d, J=17.1 Hz, 2H),
7.20–7.25 (m, 2H), 7.49–7.52 (m, 2H), 7.65–7.68 (m, 2H), 7.98 ppm (s,
2H); 13C NMR (75 MHz, CDCl3, TMS, 258C): d=20.6, 32.8, 44.9, 80.5,
Typical procedure for preparation of tricyclic D1-bipyrrolines 9 from
cyclic 2,3-disubstituted 1,4-diiodo-1,3-dienes: tBuLi (4.0 mmol, 1.5m in
pentane) was added to a solution of cyclic 2,3-disubstituted 1,4-diiodo-
1,3-diene (1.0 mmol) in diethyl ether (5 mL) at À788C. The reaction mix-
ture was then stirred at À788C for 1 h to generate 1,4-dilithio-1,3-diene
5, which was monitored by GC analysis or by TLC. HMPA (2.0 mmol)
was then added, and the reaction mixture was stirred at room tempera-
ture for 0.5 h. After addition of nitrile (2.4 mmol), the mixture was
stirred at room temperature for 2 h. The above reaction mixture was
then quenched with saturated aqueous NaHCO3 and extracted with di-
ethyl ether. The extract was washed with brine and dried over MgSO4.
The solvent was evaporated in vacuo to give a yellow oil, which was puri-
fied by column chromatography (neutral Al2O3, hexane/Et2O=4:1) to
afford tricyclic D1-bipyrrolines 9a–m.
1
9a: White solid, 90% yield (247 mg); m.p. 92–938C; H NMR (300 MHz,
CDCl3, TMS, 258C): d=1.09 (brs, 18H, CH3; 4H, CH2), 1.61 (brs, 2H),
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5677

Z. Xi et al.
122.6, 126.3, 129.8, 130.4, 133.3, 136.3, 168.3 ppm; HRMS calcd for
C22H20N279Br2: 469.9993, found: 470.0008.
13c: Colorless liquid, 90% yield (227 mg); 1H NMR (300 MHz, CDCl3,
TMS, 258C): d=0.05 (s, 18H), 1.50–1.56 (m, 2H), 1.87–1.91 (m, 2H),
2.17–2.36 (m, 4H), 5.13 ppm (s, 2H); 13C NMR (75 MHz, CDCl3, TMS,
258C): d=0.3, 30.6, 45.1, 121.3, 161.4 ppm; HRMS calcd for C14H28Si2:
252.1730, found: 252.1733.
13d: Colorless liquid, 96% yield (255 mg); 1H NMR (300 MHz, CDCl3,
TMS, 258C): d=0.04 (s, 18H), 1.49–1.56 (m, 6H), 1.29–1.34 (m, 4H),
5.24 ppm (s, 2H); 13C NMR (75 MHz, CDCl3, TMS, 258C): d=0.3, 27.5,
28.6, 43.0, 124.9, 160.7 ppm; HRMS calcd for C15H30Si2: 266.1880, found:
266.1886.
9k: White solid, 55% yield (259 mg); m.p. 190–1918C; 1H NMR
(300 MHz, CDCl3, TMS, 258C): d=1.21–1.30 (m, 4H), 1.70 (brs, 2H),
2.42–2.46 (m, 2H), 3.16 (d, J=17.1 Hz, 2H), 3.46 (d, J=17.1 Hz, 2H),
7.49 (d, J=8.4 Hz, 4H), 7.64 ppm (d, J=8.4 Hz, 4H); 13C NMR
(75 MHz, CDCl3, TMS, 258C): d=20.8, 32.9, 45.0, 80.6, 125.1, 129.3,
131.6, 133.3, 168.7 ppm; HRMS calcd for C22H20N279Br2: 469.9993, found:
469.9980.
1
9l: Light yellow liquid, 56% yield (277 mg); H NMR (300 MHz, CDCl3,
TMS, 258C): d=0.96–1.08 (m, 4H), 1.53–1.56 (m, 2H), 2.07–2.11 (m,
2H), 2.39 (s, 6H), 2.38 (d, J=18.0 Hz, 2H), 2.69 (d, J=18.0 Hz, 2H),
7.16–7.53 ppm (m, 16H); 13C NMR (75 MHz, CDCl3, TMS, 258C): d=
20.5 (2 CH2), 21.2, 32.2, 47.6, 80.2, 127.1, 128.9, 129.0, 129.2, 130.0, 135.8,
137.2, 138.4, 140.8, 173.4 ppm; HRMS calcd for C36H34N2: 494.2715,
found: 494.2722.
9m: White solid, 55% yield (228 mg); m.p. 185–1868C; 1H NMR
(300 MHz, CDCl3, TMS, 258C): d=1.40–1.43 (m, 4H), 1.81 (brs, 2H),
2.57–2.61 (m, 2H), 3.46 (d, J=17.1 Hz, 2H), 3.71 (d, J=17.1 Hz, 2H),
7.42–7.48 (m, 6H), 7.62–7.65 (m, 2H), 7.81–7.86 (m, 4H), 8.74–8.77 ppm
(m, 2H); 13C NMR (75 MHz, CDCl3, TMS, 258C): d=21.0, 32.9, 49.0,
80.9, 124.7, 125.9, 126.0, 126.9, 127.0, 128.2, 130.1, 130.9, 132.7, 133.8,
171.6 ppm; HRMS calcd for C30H26N2: 414.2096, found: 414.2099.
Acknowledgements
This work was supported by the Natural Science Foundation of China
and the Major State Basic Research Development Program
(2006CB806105). Cheung Kong Scholars Programme, Qiu Shi Science &
Technologies Foundation, BASF, Dow Corning Corporation, and Eli
Lilly China are gratefully acknowledged.
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Typical procedure for the preparation of siloles 12 from 1,2,3,4-tetrasub-
stituted 1,4-diiodo-1,3-dienes: tBuLi (4.0 mmol, 1.5m in pentane) was
added to
a solution of 1,2,3,4-tetrasubstituted 1,4-diiodo-1,3-diene
(1.0 mmol) in diethyl ether (5 mL) at À788C. The reaction mixture was
then stirred at À788C for 1 h to generate 1,4-dilithio-1,3-diene 1, which
was monitored by GC analysis or by TLC. Me3SiCN (1.0 mmol) was then
added, and the reaction mixture was stirred at room temperature for
0.5 h. The reaction mixture was then quenched with saturated aqueous
NaHCO3 and extracted with diethyl ether. The extract was washed with
brine and dried over MgSO4. The solvent was evaporated in vacuo to
give a yellow oil, which was purified by column chromatography (neutral
Al2O3, hexane) to afford siloles 12.
12a: Colorless liquid, 92% yield (256 mg); 1H NMR (300 MHz, CDCl3,
TMS, 258C): d=0.13 (s, 6H), 0.88–0.95 (m, 12H), 1.28–1.48 (m, 8H),
2.16–2.23 ppm (m, 8H); 13C NMR (75 MHz, CDCl3, TMS, 258C): d=
À3.26, 14.40, 14.60, 23.40, 23.97, 30.10, 31.84, 137.15, 152.30 ppm. The
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12b: Colorless liquid, 94% yield (233 mg); 1H NMR (300 MHz, CDCl3,
TMS, 258C): d=0.14 (s, 6H), 0.90 (t, J=7.2 Hz, 6H), 1.39–1.46 (m, 4H),
1.55–1.60 (m, 4H), 2.17 (t, J=7.8 Hz, 4H), 2.37 ppm (brs, 4H); 13C NMR
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148.8 ppm; HRMS calcd for C16H28Si: 248.1960, found: 248.1971.
Typical procedure for the preparation of (Z,Z)-dienylsilanes 13 from 2,3-
disubstituted 1,4-diiodo-1,3-dienes: tBuLi (4.0 mmol, 1.5m in pentane)
was added to
a solution of 2,3-disubstituted 1,4-diiodo-1,3-diene-
ACHTREUNG
then stirred at À788C for 1 h to generate 1,4-dilithio-1,3-diene 5, which
was monitored by GC analysis or by TLC. Me3SiCN (2.0 mmol) was then
added, and the reaction mixture was stirred at room temperature for
0.5 h. The above reaction mixture was then quenched with saturated
aqueous NaHCO3 and extracted with diethyl ether. The extract was
washed with brine and dried over MgSO4. The solvent was evaporated in
vacuo to give a yellow oil, which was purified by column chromatography
(neutral Al2O3, hexane) to afford (Z,Z)-dienylsilanes 13.
13a: Colorless liquid, 92% yield (337 mg); 1H NMR (300 MHz, CDCl3,
TMS, 258C): d=0.03 (s, 18H), 0.89 (t, J=6.6 Hz, 6H), 1.30–1.43 (m,
16H), 2.09–2.13 (m, 4H), 5.18 ppm (s, 2H); 13C NMR (75 MHz, CDCl3,
TMS, 258C): d=0.13, 14.1, 22.7, 27.4, 29.3, 31.9, 41.5, 121.5, 161.1 ppm;
HRMS calcd for C22H46Si2: 366.3138, found: 366.3136.
13b: Colorless liquid, 91% yield (319 mg); 1H NMR (300 MHz, CDCl3,
TMS, 258C): d=À0.06 (s, 18H), 6.46 (s, 2H), 7.20–7.28 (m, 6H), 7.52–
7.54 ppm (m, 4H); 13C NMR (75 MHz, CDCl3, TMS, 258C): d=À0.39,
126.5, 127.6, 128.2, 128.9, 142.0, 154.3 ppm; HRMS calcd for C22H30Si2:
350.1886, found: 350.1881.
5678
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Reactions of 1,4-Dilithio-1,3-dienes with Nitriles
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Revised: February 16, 2008
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Chem. Eur. J. 2008, 14, 5670 – 5679
ꢀ 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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5679