Generation and reaction of ammonium ylides in basic two-phase systems

Article abstract of DOI:10.1002/ejoc.200400556

Reaction of the quaternary ammonium salts 2a-i with electrophilic alkenes 3, active alkylating agents 7 or aromatic aldehydes 11, carried out in basic two-phase systems A-D, afforded cyclopropanes 4, cyanoalkenes 8 or cyanooxiranes 12 respectively, via the corresponding ammonium ylides 2^+-. The method is very simple, and gives cyclopropanes 4 and cyanoalkenes 8 in high yield. Under similar conditions, 1-cyanodienes 8aa,ba were cyclopropanated at the γ,δ-double bond with formation of vinylcyclopropanes 9a,b. The stereochemistry of the prepared cyclopropanes was elucidated from literature, ¹H NMR spectroscopic data, NOE experiments or X-ray single crystal analysis. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.

Full text of DOI:10.1002/ejoc.200400556

FULL PAPER
Generation and Reaction of Ammonium Ylides in Basic Two-Phase Systems
Anna Kowalkowska,[a] Dorota Suchołbiak,[a] and Andrzej Jon´czyk*[a]
Keywords: Alkenes / Cyclopropanes / Oxiranes / Phase-transfer catalysis / Ylides
Reaction of the quaternary ammonium salts 2a–i with electro-
cyanodienes 8aa,ba were cyclopropanated at the γ,δ-double
philic alkenes 3, active alkylating agents 7 or aromatic alde- bond with formation of vinylcyclopropanes 9a,b. The stereo-
hydes 11, carried out in basic two-phase systems A–D, af-
forded cyclopropanes 4, cyanoalkenes 8 or cyanooxiranes 12
chemistry of the prepared cyclopropanes was elucidated
from literature, 1H NMR spectroscopic data, NOE experi-
ments or X-ray single crystal analysis.
respectively, via the corresponding ammonium ylides 2+ –
.
The method is very simple, and gives cyclopropanes 4 and
cyanoalkenes 8 in high yield. Under similar conditions, 1-
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2005)
Introduction
Results and Discussion
We found that suitably substituted quaternary ammo-
nium salts, when treated with a base, generate ylides that
are useful intermediates for the preparation of cyanocyclo-
propanes, cyanoalkenes and cyanooxiranes.[9] To determine
the scope and limitation of these reactions a series of qua-
ternary ammonium salts 2 was synthesized by quaterni-
zation of aminonitriles 1a–h or aminoester 1i with dimethyl
sulfate as a alkylating agent. The oily methyl sulfates ob-
tained were transformed into crystalline perchlorates
(2a2,e,f,i; Scheme 1).
Ammonium ylides,[1] which are often generated by de-
protonation of the corresponding quaternary ammonium
salts, are prone to undergo sigmatropic rearrangements,[2]
while their reactions with electrophiles are less systemati-
cally studied. Thus, cyanotrimethylammonium iodide gen-
erates an ylide upon treatment with NaH in THF, which
then reacts with α,β-unsaturated carbonyl compounds to
afford the corresponding cyclopropanes in 21–86% yield.[3]
Pyridinium ylides, which are produced by treating pyridin-
ium salts with triethylamine in ethanol or DMF, react with
alkenes substituted with two electron-withdrawing groups
(EWGs) to give the corresponding cyclopropanes in good
yields.[4] Analogous reactions with resin-bound pyridinium
salts have also been investigated.[5] The reactions of pyridin-
ium ylides are, however, limited to strongly electrophilic al-
kenes. Furthermore, these ylides often behave as 1,3-dipoles
towards alkenes, rather than as nucleophiles.[1,4,6] Recently,
a one-pot cyclopropanation of electrophilic alkenes has
been described which utilizes α-halogenocarbonyl com-
pounds in the presence of a base and equimolar or even
catalytic amounts of tertiary amines.[7] This process, when
carried out with chiral amines and a base, leads to cyclopro-
panes with ee’s of up to 94%. Ammonium ylides, which
were generated from quaternary ammonium salts by treat-
ment with a base, were used to functionalize nitro aromatic
compounds by vicarious nucleophilic substitution (VNS).[8]
[a] Warsaw University of Technology, Faculty of Chemistry,
Koszykowa 75, 00-662 Warszawa, Poland
Fax: +48-22-628-2741
E-mail: ankowal@ch.pw.edu.pl
anjon@ch.pw.edu.pl
Supporting information for this article is available on the
WWW under http://www.eurjoc.org or from the author.
Scheme 1.
Eur. J. Org. Chem. 2005, 925–933
DOI: 10.1002/ejoc.200400556
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925

A. Kowalkowska, D. Suchołbiak, A. Jon´czyk
FULL PAPER
The reaction of salt 2a1 with several bases in different isomers in high yields (Table 1). Hydrolysis of esters in sys-
solvents [NaNH2/liq. NH3, NaH/DMF, tBuOK/DMSO tem A, observed in the case of methyl acrylate (3b), was
and 50% aq. NaOH/dichloromethane with benzyltrieth- prevented by the use of large amounts of dichloromethane.
ylammonium chloride (TEBAC) as a phase-transfer cata- Under these conditions the reactions proceeded even more
lyst[10–13]] revealed that ylide 2a1+ – is not prone to undergo efficiently in system A than in system B (powdered K2CO3
sigmatropic rearrangements. These results indicate that sig- in dichloromethane; Table 1, entries 2 and 3). Attempted
matropic rearrangements of ylides 2+ – should not compete synthesis of cyclopropane 4ae from 2a1 and vinyl ketone 3e
with their reactions with electrophiles.
failed in system A, while the same reaction carried out in
Deprotonation–alkylation of 1a1 requires rather harsh system B gave (Z,E)-4ae in excellent yield. System B is also
phase-transfer catalysis (PTC) conditions (mixture of conc. recommended for the preparation of 4ad and 4af from 2a1
and solid NaOH, elevated temp.),[14] while the presence of and α,β-unsaturated carbonyl compounds 3d and 3f, respec-
the trimethylammonium group in 2a1 significantly de- tively (Table 1). Methacrylonitrile (5) and crotononitrile
creases its pKa, thus allowing the generation of 2a1+ – under were allowed to react with 2a1 in systems A and B, but
the mild conditions of a typical two-phase basic system [the only the former nitrile formed one isomer of 1,2-dicyano-
pKa values of 1a1 and 2a1, estimated from the acidity coef- 1-methyl-2-phenylcyclopropane (6)[22] in 27% yield
ficients of substituents and the assumed value for methane (Scheme 3). This reactivity pattern is not very surprising as
(pKa = 40),[15] are 20.5 and 11.5, respectively].
decreased activity of α- and particularly β-substituted elec-
Preliminary experiments consisted of stirring salt 2a1 trophilic alkenes in Michael reactions is well known.[23]
with an excess of acrylonitrile (3a) in the presence of 50%
aq. NaOH, with TEBAC as catalyst, in toluene, diethyl
ether or dichloromethane. When the reaction was carried
out in the latter solvent, cyclopropane 4aa[16–18] was iso-
lated in 95% yield, while the product yield was rather low
in the other two solvents. These results are presumably due
Scheme 3.
to the limited solubility of 2a1 (and possibly 2a1+ –) in tolu-
ene and diethyl ether.
A review of the literature data concerning the generation
and reactions of ylides (particularly phosphonium ones) un-
In the reactions described so far, trimethylammonium (as
trimethylamine) acts as a leaving group. Salts 2a2 and 2a3,
which contain cyclic amine fragments, were allowed to react
with nitrile 3a and esters 3b,c to give the corresponding
der PTC conditions revealed that some processes are car-
ried out with a catalyst and others without.[19] When the
onium salt is deprotonated at the phase boundary of the
cyclopropanes in equally good yields. This seems to indicate
two-phase system, the resulting ylide can dissolve in the or-
that the structure of the amine leaving group is not a signifi-
ganic phase without the aid of the catalyst. On the other
cant factor controlling these reactions.
hand, the onium salt itself may facilitate generation of the
Alkenes with EWG substituents are typically prepared by
ylide by acting as a catalyst. Reaction of 2a1 with 3a carried
Knoevenagel[24] or Wittig[25,26] reactions, or their modified
versions. A procedure using sulfonium and arsonium ylides
out in the presence of 50% aq. NaOH in dichloromethane
without TEBAC (system A) led to formation of 4aa in 96%
yield (Scheme 2, Table 1). Since the catalyst is not required
to obtain high yields of the product, all experiments in basic
two-phase systems with quaternary ammonium salts 2 were
carried out without a phase-transfer catalyst.
for the preparation of alkenes lacking EWGs has also been
described.[27,28]
Reactions of 2a1 with active alkylating agents 7a–d (usu-
ally used in excess), which were carried out in system A,
resulted in the formation of four 1-cyano-1-phenyl alkenes
8aa–ad[29–31] in high yields. Apparently, the alkylated qua-
ternary ammonium salts easily undergo a Hofmann elimi-
nation reaction (Scheme 4, Table 2).
Scheme 2.
The salt 2a1 was reacted with a series of electrophilic
alkenes 3b,c,g in system
A to give cyclopropanes
4ab,[20]4ac[16] and 4ag, respectively, as mixtures of Z and E Scheme 4.
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Ammonium Ylides in Basic Two-Phase Systems
FULL PAPER
Table 1. Synthesis of cyclopropanes 4 in reactions of salts 2 with electrophilic alkenes 3 under conditions A–D
Entry
Salt
Alkene
3/2 [mol/mol]
Time [h]
Conditions[a]
Product
Yield [%]
Isomer
Z/E[b]
1
2
3
4
5
6
7
8
2a1
2a1
2a1
2a1
2a1
2a1
2a1
2a1
2a2
2a2
2a3
2b
2b
2b
2b
2b
2b
2b
2c
3a
3b
3b
3c
3d
3e
3f
3g
3b
3c
3a
3a
3b
3b
3c
3e
3f
3g
3a
3b
3b
3c
3e
3f
3g
3a
3b
3c
3e
3f
3g
3a
3b
3c
3d
3e
3e
3f
3g
3g
3a
3b
3c
3e
3e
3f
3g
3a
3b
3c
3e
3g
3b
3a
3b
3b
3c
6
10
5
3
7
5
1
1
10
3
6
3
10
5
3
5
1
1
3
10
5
3
5
1
1
6
10
3
5
1
1
6
10
3
5
5
5
1
5
2
5
7.5
7.5
3.5
6
6
4
5
6.5
4
2
5
6
5
5
7
4
2
5
6
5
5
7
6.5
2
5.5
5
7
5.5
4
2.5
4.5
4
5.5
6.5
3
3
3.5
5
2.5
6
5.5
6.5
2
A
A
B
A
B
B
B
A
A
A
A
A
A
B
A
B
B
4aa[16–18]
4ab[20,21]
4ab[20,21]
4ac[16]
4ad
96
91
80
91
46
90
60
92
78
72
83
81
84
61
80
84
69
91
46
88
79
65
64
37
81
41
90
52
81
83
80
71
64
81
46
32
89
59
53
19
81
90
60
40
89
79
71
82
61
82
92
92
29
36
40
51
27
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
55:45[c]
80:20
82:18[c]
78:22
62:38
81:19
76:24
90:10
78:22[c]
80:20[c]
67:33[c]
50:50
71:29
73:27[c]
76:24
75:25
69:31
83:17
50:50
51:49
53:47[c]
45:55
60:40
63:37
90:10
–
4ae
4af
4ag
9
4ab[20,21]
4ac[16]
4aa[16–18]
4ba
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
4bb
4bb
4bc
4be
4bf
B
4bg
A
A
B
A
B
B
B
A
A
A
B
4ca
2c
4cb
2c
4cb
2c
4cc
2c
4ce
2c
4cf
2c
4cg
[d]
2d
2d
2d
2d
2d
2d
2e
4da
–
4db
Z + E
81:19
–
80:20
86:14
–
[d]
4dc
–
4de
Z + E
Z + E
Z
B
4df
A
A
A
A
C
B
C
C
A
C
A
A
A
B
C
C
A
A
A
A
B
4dg
4ea
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
Z + E
32:68
26:74
24:76
42:58[d]
33:67
33:67
37:63[d]
64:36[d]
71:29[d]
31:69[d]
24:76
27:73
25:75
88:12
65:35
23:77
48:52
48:52
41:59
52:48
20:80
66:34[d]
69:31
79:21
77:23
79:21
2e
4eb
2e
4ec
2e
4ed
2e
4ee
2e
4ee
2e
4ef
2e
1
1
6
10
3
5
5
1
1
4eg
2e
4eg
2f
4fa
2f
4fb
2f
4fc
2f
4fe
2f
4fe
2f
4ff
2f
4
2
3
5.5
3
7
4
6
4fg
2g
2g
2g
2g
2g
2h
2i
6
4ga
10
1.5
5
1
5
10
5
5
4gb
4gc
4ge
A
B
D
D
A
D
4gg
4hb
4ia[21]
4ib[21]
4ib[21]
4ic
2i
6.5
1.5
6
2i
2i
2
[a] System A: 50% aq. NaOH/CH2Cl2; system B: powdered K2CO3/CH2Cl2; system C: powdered K2CO3/CH2Cl2/DMSO; system D:
powdered K2CO3/powdered NaOH/CH2Cl2. [b] Determined by NMR spectroscopy. [c] Determined by GC. [d] Stereochemistry not
determined.
Equimolar amounts of 2a1 and 7a gave crystalline prod- crowded γ,δ-double bond in diene 8aa by 2a1. Use of an
uct 9a in 23% yield (Scheme 5). The key step of this reac- excess of 2a1 (2a1/7a Ϸ 2) did not increase the yield of 9a,
tion consists of cyclopropanation of the less sterically although intermediate diene 8aa[29] could be prepared in
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A. Kowalkowska, D. Suchołbiak, A. Jon´czyk
FULL PAPER
yields of up to 92% from 7a and 2a1 (molar ratio Ϸ 15). limited to active alkylating agents and only some ammo-
Cyclopropane 9a was prepared from salt 2a1 and isolated nium salts.
diene 8aa in high yield (70%).
Reaction of sulfur ylides with carbonyl compounds is a
well-established method used for the synthesis of oxir-
anes.[35–38] Ylides of other elements (arsenic,[39–41] tel-
lurium,[42,43] antimony,[44] selenium[45,46] and bismuth[47]
)
have also been applied for this purpose. The preparation of
oxiranes substituted with EWGs is conveniently carried out
by a Darzens condensation.[48,49]
Salt 2a1 reacted with aromatic aldehydes 11 in system A
to give oxiranes 12 in moderate yields (Scheme 7, Table 3),
but attempted extension of this reaction to other aldehydes,
failed. Nevertheless, it has been demonstrated for the first
time that ammonium salts react with some aromatic alde-
hydes in the presence of a base to give oxiranes 12.
Scheme 5.
Attempted reactions of 2a1 with 2-(chloromethyl)thio-
phene (7e) and some other alkylating agents did not give
the expected alkenes, but instead produced (E)-dicyanostil-
bene (10a).[34] Compound 10a was also formed when 2a1
was stirred in system A without an alkylating agent, but its
yield was observed to be dependent on the concentration of
2a1. Thus, 6% yield was obtained in about 7 wt.-% solution
in dichloromethane, while 62% yield was obtained when a
1.5 wt.-% solution was used. The formation mechanism of
10a is not clear at the moment, but the alkylation–elimi-
nation sequence depicted in Scheme 6 seems plausible. This
mechanism is analogous to that described for the synthesis
of 10a from chloro(phenyl)acetonitrile under PTC condi-
tions.[34] Therefore preparation of alkenes (and dienes) is
Scheme 7.
The reactivity of the salts depends on the nature of the
substituents present in the para position of phenyl ring.
Thus, salt 2b, which possesses an electron-donating meth-
oxy group, reacts with all the above-mentioned electrophiles
to give cyclopropanes 4ba–bc,be–bg (Table 1), cyanoalkenes
8ba and 8bd[32] (Table 2), vinylcyclopropane 9b (Scheme 5),
oxiranes 12ba and 12bc (Table 3) and dicyanostilbene
10b[52] (Scheme 6), usually in good yield. On the other
hand, salt 2c, which is substituted with an electron-with-
drawing cyano group, reacts only with electrophilic alkenes
to give the cyclopropanes 4ca–cc,ce–cg in moderate yield
(Table 1). The reactivity of salt 2b, which is similar to that
of 2a, is due to the high electron density on the ylidic car-
bon atom.
Scheme 6.
Table 2. Synthesis of cyanoalkenes 8 in reactions of salts 2 with alkylating agents 7 in system A[a]
Entry
Salt
Alkylating agent
7/2 [mol/mol]
Time [h]
Product
Yield
Isomer ratio[b]
87:13[c]
1
2
3
4
5
6
7
8
9
2a1
2a1
2a1
2a1
2a2
2a3
2b
7a
7b
7c
7d
7d
7a
7a
7d
7a
7c
7d
7e
15
5
1.25
1
1.5
3
7
2
5
2.5
1.5
2.5
1.5
7
4
7.5
8aa[29]
8ab
75
94
54
80
82
77
85
71
75
71
86
76
[d]
–
8ac[30]
8ad[31]
8ad[31]
8aa[29]
8ba
–
[d]
[d]
–
–
[d]
1
20
15
1
10
1.25
1
85:15[e]
63:37[c]
[d]
2b
8bd[32]
8ga
–
2g
78:22
70:30
89:11
69:31
10
11
12
2g
8gc
2g
8gd[33]
8ge
2g
1
[a] 50% aq. NaOH/CH2Cl2. [b] Stereochemistry not determined. [c] Determined by 1H NMR spectroscopy. [d] One isomer. [e] Determined
by GC.
928
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Ammonium Ylides in Basic Two-Phase Systems
FULL PAPER
Table 3. Synthesis of oxiranes 12 in reactions of salts 2 with aldehydes 11 in system A[a]
Entry
Salt
Aldehyde
11/2 [mol/mol]
Time [h]
Temperature [°C]
Product
Isomer
Yield [%]
1
2
3
4
5
6
7
8
9
2a1
2a1
2a1
2a1
2a1
2b
11a
11b
11c
11d
11e
11a
11c
11a
11c
1
1
1
0.5
0.5
1
1
2
1
8
9
9
8
8
15
10
7
40
40
40
40
40
40
40
20–25
20–25
12aa[16]
12ab[50]
12ac[16]
12ad[51]
12ae
Z
Z
Z
Z
Z
Z
Z
Z + E
Z + E
49
48
47
46
45
35
32
52
32
12ba[16]
12bc
2b
2g
2g
12ga
12gc
10
[a] 50% aq. NaOH/CH2Cl2.
Salts 2b–i (Scheme 1) were allowed to react in basic two- hand, 2d gave complex mixtures of products with 7a,c or
phase systems with electrophilic alkenes 3 and/or alkylating 11a in system A.
agents 7 and/or aromatic aldehydes 11. The results of these
experiments are presented in Table 1, Table 2 and Table 3,
respectively.
Salts substituted with a 2-furyl (2e) or a 2-thienyl (2f)
group reacted smoothly with 3 to give the corresponding
cyclopropanes. Addition of DMSO to reaction mixtures
containing powdered K2CO3 in dichloromethane (system
C) increased the solubility of 2e,f (and possibly 2e,f+ –) to
give the products in high yields. The reaction of 2f with
3c produced, in addition to (Z,E)-4fc (yield 60%), a small
amount of dimer 10f[53,54] (yield 19%), but in more concen-
trated systems these yields changed to 84% and 4%, respec-
tively. Dimer 10f was also produced when 2f was allowed
to react with methacrylonitrile (5) or crotononitrile, or
when an electrophile was absent from system A. Formation
of 10f is reasonably explained by an alkylation–elimination
route, as depicted in Scheme 6.
The reaction of salt 2d with a large excess of 3a, carried
out in system A, produced, in addition to cyclopropane
4da, the cyanoethyl derivative 13 (an isomeric tricyanocy-
clopentane structure A was excluded on the basis of APT
measurements). The formation of 13 from isolated 4da and
3a (19% yield) does not explain how it is produced from
2d and 3a, because cyanoethylation of phenyl-substituted
cyclopropane 4aa essentially does not occur under the con-
ditions of system A. Because of these observations, we sug-
gest that formation of 13 occurs by deprotonation of the
linear diadduct at γ-C, followed by its cyclization
(Scheme 8).
Of the two salts 2g,h both of which have a substituted
β,γ-double bond, only the first one gave satisfactory results
when reacted with electrophiles 3, 7 and 11. Isolation of
pure oxiranes 12 was rather troublesome due to both in-
complete conversion of 11 and
a Cannizzaro side-
reaction. The use of TEBAC as a catalyst inhibits the PTC
Cannizzaro reaction of benzaldehyde.[55] However, the use
of this catalyst in the reaction of 2g with 11a,c carried out
in system A, did not change the distribution of products.
Out of all the electrophilic alkenes that react with salt
2h, only ester 3b gave a mixture of (Z)- and (E)-4hb in low
yield. Due to the many negative results with 2h, its reactions
with electrophiles 7 and 11 were not attempted.
Salt 2i, which is substituted with an ester group, reacted
with 3a–c to give cyclopropanes 4ia–ic[21] in 27–51% yield.
Because 2i is a weaker C-H acid than the cyano-substituted
salt 2a1, its reactions were usually carried out in the pres-
ence of a powdered mixture of NaOH and K2CO3 in
dichloromethane (solid-liquid system D). Alkylation of 2i
with 7a (in system A) or 7d (in system D) did not occur or
gave a mixture of products in low yields.
Scheme 8.
The reaction of 2d with 3a or 3c yielded one isomer of
The stereochemistry of the majority of the cyclopropanes
1
cyclopropanes 4da,dc respectively, which was isolated by prepared was assigned on the basis of reported H NMR
troublesome column chromatography and/or crystalli- spectroscopic data for (Z)-4ab and (E)-4ab,[21] and for some
zation. Preparation of cyclopropanes 4db,dg (in system A) products was confirmed by NOE measurements. The ste-
and 4de,df (in system B) was also successful. On the other reochemistry of cyclopropanes (Z)-4aa and (E)-4gg was un-
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A. Kowalkowska, D. Suchołbiak, A. Jon´czyk
FULL PAPER
to 0 °C, and a solution of NaCN (2.70 g, 0.055 mol) in H2O
(10 mL) was added dropwise maintaining the temperature at 0 °C.
Stirring was continued for 19 h, then the mixture was dissolved in
H2O (90 mL), extracted with CH2Cl2 (3 × 35 mL), and the com-
bined organic extracts were washed with water (3 × 40 mL) and
dried (MgSO4). The solvent was evaporated and the residue was
used without further purification.
equivocally confirmed by single-crystal X-ray analysis (Fig-
ure 1 and Figure 2, respectively).
2-(Dimethylamino)-4-methylpent-3-enenitrile (1g): A solution of
KCN (9.8 g, 0.15 mol) in H2O (15 mL) was added dropwise over
1 h to a magnetically stirred solution of 3-methyl-2-butenal (8.4 g,
9.6 mL, 0.1 mol) and dimethylamine hydrochloride (12.2 g, 0.15
mol) in acetonitrile (40 mL) at –10 °C maintaining the temperature
below –5 °C. Stirring was continued for 20 h. The mixture was dis-
solved in H2O (200 mL), extracted with Et2O (4 × 30 mL), and the
combined organic extracts were washed with water (4 × 30 mL)
and dried (MgSO4). The solvent was evaporated and the residue
was purified by distillation under reduced pressure.
Figure 1. Crystal structure of cyclopropane (Z)-4aa
Synthesis of Salts 2: Me2SO4 [1a1,1b,1c,1d,1g/Me2SO4 (mol/mol) =
1.2; 1a2,1a3,1e,1f/Me2SO4 (mol/mol) = 1.5; 1h/Me2SO4 (mol/mol)
= 1.8; 1i/Me2SO4 (mol/mol) = 2.0] was added to a solution of
aminonitrile 1a–h or aminoester 1i (0.03 mol) in CH2Cl2 (50 mL)
at 0 °C. The mixture was left without stirring at 0 °C for 2 h and
then at 20–25 °C for 24 h. The solvent was then evaporated and the
residue was left for a further 48 h. If the residue solidified (1a1,
1a3, 1b–d, 1g,h), acetone (10–25 mL) was added, and the crystals
were filtered off, washed with acetone (4 × 5–10 mL) and dried
under vacuum. If an oil was obtained (1a2, 1e,f, 1i), it was dissolved
in H2O (20–50 mL), extracted with CH2Cl2 (3 × 10–15 mL), and
the water phase was treated with 60% aq. HClO4 (5.4 g, 3.4 mL,
0.032 mol). The resultant precipitate was filtered, washed with
water (6–8 × 10–15 mL), then with diethyl ether (3–4 × 5–10 mL)
and dried.
Figure 2. Crystal structure of cyclopropane (E)-4gg
Synthesis of Cyclopropanes 4
Conditions A (50% aq. NaOH/CH2Cl2): 50% aq. NaOH (7.5 mL)
was added dropwise to a vigorously stirred solution of salt 2
(3 mmol) and electrophilic alkene 3 (amount given in Table 1) in
CH2Cl2 (45 mL). The stirring was continued for the time given in
Table 1, the mixture was diluted with water (100 mL), and the
phases were separated. The aqueous phase was extracted with
CH2Cl2 (3 × 25 mL), and the combined organic extracts were
washed with water (3 × 40 mL), dried (MgSO4), and the solvent
was evaporated. The residue was passed through a short pad of
silica gel, and the crude products were further purified by Kugel-
rohr distillation, crystallisation or by column chromatography
(Table 1).
Experimental Section
General Remarks: Melting (determined in a capillary tube appara-
tus) and boiling points are uncorrected. H and 13C NMR spectra
1
were measured in CDCl3 or [D6]DMSO on a Varian Gemini 200,
Varian Gemini 400 or Varian Gemini 500 spectrometer (at
200 MHz, 400 MHz and 500 MHz for H and 50 MHz, 100 MHz
1
and 125 MHz for 13C respectively). Chemical shifts (δ) are given in
ppm relative to TMS and coupling constants (J) are given in hertz.
GC analyses were performed with a Hewlett–Packard 5890 ser. II
chromatograph, equipped with an HP50+ capillary column. Ele-
mental analyses were performed with a Perkin–Elmer CHNO/S Ser.
II 2400 microanalyser. HR-MS analyses were performed with an
AMD 604 spectrograph. Column chromatography was carried out
with Merck Kieselgel 60 (230–400 mesh) with a hexane/EtOAc
(gradient) mixture as eluent. All solvents used were commercially
available; Me2SO4 was purified before use.[56]
Conditions B (K2CO3/CH2Cl2): Powdered K2CO3 (30 mmol, 4.15 g)
was added to a vigorously stirred solution of salt 2 (3 mmol) and
electrophilic alkene 3 (amount given in Table 1) in CH2Cl2 (45 mL).
Stirring was continued for the time given in Table 1, then the mix-
ture was diluted with water (100 mL), the phases were separated,
and the aqueous phase was extracted with CH2Cl2 (3 × 25 mL).
The combined organic extracts were washed with water (3 ×
40 mL) [in the case of reactions with salts 2a2 and 2a3 the com-
bined organic extracts were first washed with 3% aq. HCl (2 ×
30 mL)], dried (MgSO4), and the solvent was evaporated. The resi-
due was passed through a short pad of silica gel, and the crude
products were further purified by Kugelrohr distillation, crystallis-
ation or by column chromatography (Table 1).
Synthesis of Aminonitriles 1a–h and Aminoester 1i: Aminonitriles
1a1,[57]1a2,[57,58]1a3,[57,59]1b,[60]1d,[61]1e,[62,63]1f,[57,58]1h,[64]
and
aminoester 1i[65] were synthesized according to literature methods.
1-(4-Cyanophenyl)-1-(dimethylamino)acetonitrile (1c): 4-Cyanobenz-
aldehyde (6.56 g, 0.055 mol) was addedto a mechanically stirred
solution of Na2S2O5 (10.46 g, 0.055 mol) in H2O (35 mL). After
0.5 h a 40% aq. solution of dimethylamine (6.20 g, 7.0 mL, 0.055
mol) was added dropwise. The mixture was stirred for 0.5 h, cooled
Conditions
C
(K2CO3/CH2Cl2/DMSO): Powdered K2CO3
(30 mmol, 4.15 g) was added to a vigorously stirred solution of salt
930
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Ammonium Ylides in Basic Two-Phase Systems
FULL PAPER
2 (3 mmol) and electrophilic alkene 3 (amount given in Table 1) in
CH2Cl2 (40 mL) and DMSO (12 mL). Stirring was continued for
the time given in Table 1. The mixture was then diluted with water
(100 mL), the phases were separated, and the aqueous phase was
extracted with CH2Cl2 (3 × 25 mL). The combined organic extracts
were washed with water (4 × 40 mL), dried (MgSO4), and the sol-
vent was evaporated. The residue was passed through a short pad
of silica gel, and the crude products were further purified by Kugel-
rohr distillation, crystallisation or by column chromatography
(Table 1).
hyde 11 (amount given in Table 3) in CH2Cl2 (40 mL). Stirring was
continued at the temperature and for the time given in Table 3,
then the mixture was diluted with water (80 mL), the phases were
separated, and the aqueous phase was extracted with CH2Cl2 (3 ×
30 mL). The combined organic extracts were washed with water (3
× 30 mL), dried (MgSO4), and the solvent was evaporated. The
residue was passed through a short pad of silica gel and the crude
products were purified by Kugelrohr distillation, crystallisation or
by column chromatography (Table 3).
Synthesis of 1-(2-Cyanoethyl)-2-naphthalen-1-ylcyclopropane-1,2-di-
carbonitrile (13): 50% aq. NaOH (7.5 mL) was added dropwise to
a vigorously stirred solution of salt 2d (3 mmol, 1.0 g) and acryloni-
trile (3a; 30 mmol, 1.6 g, 2.0 mL) in CH2Cl2 (15 mL). Stirring was
continued for 7 h, ten the mixture was diluted with water (50 mL),
the phases were separated, and the aqueous phase was extracted
with CH2Cl2 (3 × 15 mL). The combined organic extracts were
washed with water (4 × 25 mL), dried (MgSO4), and the solvent
was evaporated. The residue was passed through a short pad of
Conditions D (NaOH/K2CO3/CH2Cl2): Powdered NaOH (30 mmol,
1.2 g) and powdered K2CO3 (15 mmol, 2.1 g) were added to a vig-
orously stirred solution of salt 2 (3 mmol) and electrophilic alkene
3 (amount given in Table 1) in CH2Cl2 (45 mL). Stirring was con-
tinued for the time given in Table 1. Work-up and purification were
as described for conditions A.
Synthesis of 1-Methyl-2-phenylcyclopropane-1,2-dicarbonitrile (6):
50% aq. NaOH (10 mL) was added dropwise to a vigorously stirred
solution of salt 2a1 (5 mmol, 1.43 g) and methacrylonitrile (5; silica gel and the crude product was further purified by column
25 mmol, 1.68 g, 2.1 mL) in CH2Cl2 (50 mL). Stirring was contin-
ued for 7.5 h, then the mixture was diluted with water (100 mL),
the phases were separated, and the aqueous phase was extracted
with CH2Cl2 (3 × 25 mL). The combined organic extracts were
washed with water (3 × 40 mL), dried (MgSO4), and the solvent
was evaporated. The residue was passed through a short pad of
silica gel, and the crude product was further purified by column
chromatography and crystallization.
chromatography.
X-ray Crystallographic Study: Data collection for (Z)-4aa was per-
formed on a Kuma KM4CCD κ-axis diffractometer with graphite-
monochromated Mo-Kα radiation (Table 4). The crystal was posi-
tioned at 65 mm from the KM4CCD camera. 748 Frames were
measured at 1.6° intervals with a counting time of 10 s. The data
were corrected for Lorentz and polarization effects. No absorption
correction was applied. Data reduction and analysis were carried
out with the Kuma Diffraction programs (Wrocław). The structure
was solved by direct methods[66] and refined by using SHELXL.[67]
The refinement was based on F2 for all reflections except those with
very negative F2. Weighted R factors (wR) and all goodness-of-fit
S values are based on F2. Conventional R factors are based on F,
Synthesis of Alkenes 8: 50% aq. NaOH (5 mL) was added dropwise
to a vigorously stirred solution of salt 2 (3 mmol) and alkylating
agent 7 (amount given in Table 2) in CH2Cl2 (15 mL). Stirring was
continued for the time given in Table 2, then the mixture was di-
luted with water (50 mL), the phases were separated, and the aque-
ous phase was extracted with CH2Cl2 (3 × 15 mL). The combined
organic extracts were washed with water (3 × 25 mL), dried
(MgSO4), and the solvent was evaporated. The residue was passed
through a short pad of silica gel and the crude products were fur-
ther purified by Kugelrohr distillation, crystallization or by column
chromatography (Table 2).
with F set to zero for negative F2. The Fo Ͼ 2σ(Fo2) criterion was
2
used only for calculating R factors and is not relevant to the choice
of reflections for the refinement. The R factors based on F2 are
about twice as large as those based on F. All hydrogen atoms were
located from a differential map and refined isotropically. Scattering
factors were taken from Tables 6.1.1.4 and 4.2.4.2 in ref.[68]
Data collection for (E)-4gg was carried out using a KUMA KM-
Synthesis of 2-(2-Cyano-2-phenylethenyl)-1-phenylcyclopropanecar-
bonitrile (9a) and 2-[2-Cyano-2-(4-methoxyphenyl)ethenyl]-1-(4-me- 4 diffractometer with graphite-monochromated Mo-Kα radiation
thoxyphenyl)cyclopropanecarbonitrile (9b): 50% aq. NaOH (6 mL)
was added dropwise to a vigorously stirred solution of salt 2a1 or
2b (4.5 mmol) and cyanodiene 8aa or 8ab (4.5 mmol) in CH2Cl2
(15 mL). Stirring was continued for 2 h, then the mixture was di-
luted with water (50 mL), the phases were separated, and the aque-
ous phase was extracted with CH2Cl2 (3 × 15 mL). The combined
organic extracts were washed with water (3 × 25 mL), dried
(MgSO4), and the solvent was evaporated. The residue was passed
through a short pad of silica gel and the products were purified by
column chromatography and crystallized.
(Table 4). The data were collected at room temperature using the
ω-2θ scan technique. The intensity of the control reflections varied
by less than 5%, and a linear correction factor was applied to ac-
count for this effect. The data were also corrected for Lorentz and
polarization effects, but no absorption correction was applied. The
structure was solved by direct methods[66] and refined by full-ma-
trix least-squares techniques (SHELXL).[67] The non-hydrogen
atoms were refined anisotropically, whereas the H-atoms were
placed in the calculated positions and their thermal parameters
were refined isotropically. The atomic scattering factors were taken
from the International Tables of Crystallography.[69]
Synthesis of 2,3-Diarylbut-2-enedinitriles 10a, 10b and 10f: 50% aq.
NaOH (20 mL) was added dropwise to a vigorously stirred solution
of salt 2a1, 2b or 2f (7 mmol) in CH2Cl2 (100 mL). Stirring was
continued for 6 h, then the mixture was diluted with water
(100 mL), the phases were separated, and the aqueous phase was
extracted with CH2Cl2 (3 × 30 mL). The combined organic extracts
were washed with water (3 × 50 mL), dried (MgSO4), and the sol-
vent was evaporated. The residue was passed through a short pad
of silica gel and the crude products were crystallised.
CCDC-198409 [for (E)-4gg] and CCDC-198410 [for (Z)-4aa] con-
tain the supplementary crystallographic data for this paper. These
data can be obtained free of charge from The Cambridge Crystallo-
graphic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
Supporting Information: Yields, physical and spectral properties, el-
emental analyses or HRMS of aminonitriles 1c,g, salts 2, cyclopro-
panes 4, 6, 9 and 13, alkenes 8, dimers 10 and oxiranes 12. Investi-
gation of the stereochemistry of cyclopropanes 4 and oxiranes 12
is also described (see also the footnote on the first page of this
article).
Synthesis of Oxiranes 12: 50% aq. NaOH (10 mL) was added drop-
wise to a vigorously stirred solution of salt 2 (7 mmol) and alde-
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A. Kowalkowska, D. Suchołbiak, A. Jon´czyk
Table 4. Summary of data collection, structure solution and refinement details for (E)-4gg and (Z)-4aa
FULL PAPER
(E)-4gg
(Z)-4aa
Empirical formula
Formula mass
Temperature [K]
Wavelength [Å]
C14H15NO2S
261.33
293(2)
0.71073
C11H20N2
180.29
293(2)
0.71073
Crystal system
Space group
monoclinic
C2/c
monoclinic
P21/n
a [Å], α [°]
b [Å], β [°]
30.319(6), 90
5.9330(10), 96.28(3)
14.940(3), 90
6.4370(13), 90
8.5400(17), 95.82(3)
16.630(3), 90
c [Å], γ [°]
Volume [Å3]
2671.3(9)
909.5(3)
Z
8
4
Density (calculated)
Absorption coefficient
F(000)
1.300 mg/m3
1.317 mg/m3
0.236 mm–1
1104
0.078 mm–1
400
Crystal size
θ range for data collection
Index ranges
0.3 × 0.3 × 0.28 mm
1.35 to 30.08
–30 Յ h Յ 0, 0 Յ k Յ 8, –16 Յ l Յ 16
3265
3205 [R(int) = 0.0588]
full-matrix least-squares on F2
3198/0/178
0.7 × 0.7 × 0.23 mm
3.43 to 25.00
–7 Յ h Յ 7, –10 Յ k Յ 10, –19 Յ l Յ 19
13502
1607 [R(int) = 0.0634]
full-matrix least-squares on F2
1607/0/151
Reflections collected
Independent reflections
Refinement method
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I Ͼ 2σ(I)]
R indices (all data)
Largest diff. peak and hole
1.026
1.142
R1 = 0.0587, wR2 = 0.1620
R1 = 0.0887, wR2 = 0.2017
0.540 and –0.314 eÅ3
R1 = 0.0600, wR2 = 0.1740
R1 = 0.0786, wR2 = 0.1982
0.251 and –0.164 eÅ3
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