1-Alkyl-4-dialkylaminopyridinium halides as phase-transfer catalysts in dichlorocarbene reactions

Article abstract of DOI:10.1007/s007060200009

A series of 1-alkyl-4-dialkylaminopyridinium halides derived from 4-dimethylamino- and 4-morpholinopyridines were synthesized and tested as phase-transfer catalysts in three typical reactions of dichlorocarbene: dehydration of benzamide, N-formylation of diphenylamine, and dichlorocyclopropanation of styrene. The catalytic performance of the above compounds was found comparable or higher than that of conventional quaternary ammonium catalysts. The influence of catalyst structure on the reactivity was evaluated.

Full text of DOI:10.1007/s007060200009

Monatshefte f uÈ r Chemie 133, 313±321 ꢀ2002)
1
-Alkyl-4-dialkylaminopyridinium Halides
as Phase-Transfer Catalysts
in Dichlorocarbene Reactions
Ï
Ã
Gytis-Kazimieras Kupetis, Gintautas Saduikis , Ona Nivinskien e_ ,
and Olegas Eicher-Lorka
Institute of Chemistry, LT-2600 Vilnius, Lithuania
Summary. A series of 1-alkyl-4-dialkylaminopyridinium halides derived from 4-dimethylamino-
and 4-morpholinopyridines were synthesized and tested as phase-transfer catalysts in three typical
reactions of dichlorocarbene: dehydration of benzamide, N-formylation of diphenylamine, and di-
chlorocyclopropanation of styrene. The catalytic performance of the above compounds was found
comparable or higher than that of conventional quaternary ammonium catalysts. The in¯uence of
catalyst structure on the reactivity was evaluated.
Keywords. Carbenes; 1-Alkyl-4-dialkylaminopyridinium halides; 4-Dimethylaminopyridine; Phase-
transfer catalysis; Quaternary pyridinium salts.
Introduction
Makosza has established a simple and convenient two-phase catalytic method of
dihalocarbene generation from haloform and aqueous alkali in 1969 [1]. A further
development, solid-liquid phase-transfer catalysis ꢀPTC) system with powdered
KOH or NaOH has been introduced as a very effective dihalocarbene precursor
which allows exclusion of the undesirable action of coextracted water [2, 3]. In
1982, Regen and Singh have applied simultaneous ultrasonication and mechanical
stirring of the solid±liquid two-phase system to afford excellent yields of dichloro-
carbene adducts [4]. Finally, the principles of PTC and ultrasonication have been
combined by Xu et al. for selective insertion of dihalocarbenes into strained carbon±
hydrogen bonds [5].
Despite the progress in methodology, the choice of catalyst was, for a long
time, limited to simple quaternary ammonium salts, mainly due to the widely ac-
cepted view regarding benzyltriethylammonium chloride ꢀTEBA) as the optimal
catalyst [6, 7]. Although some authors have pointed out that more lipophilic quat-
ernary salts show a better performance in the presence of concentrated aqueous
alkali [8, 9], there are only a few examples reporting the use of other types of
quaternary ammonium catalysts in dihalocarbene reactions [10, 11]. Crown ethers
à Corresponding author. E-mail: lorka@takas.lt

3
14
G.-K. Kupetis et al.
as an alternative are of limited value because of their high price and toxicity [12,
3]. Meanwhile, the search for new stable, active, selective, and non-toxic catalysts
became urgent.
1
Quaternary pyridinium salts possess numerous signi®cant advantages in com-
parison with quaternary ammonium catalysts including enhanced thermal stability
and simple recycling from the reaction mixture. Therefore they have found use
in PTC reactions of nucleophilic aromatic substitution and dehydrohalogenation
where high temperatures are normally employed [10, 12±15]. Thus, branched 1-
alkyl-4-dialkylaminopyridinium salts proved to be effective catalysts for the prep-
aration of aromatic bis-etherimides [14], whereas bis-aminopyridinium salts have
found applications for the alkylation of dianionic phenoxides and thiophenoxides
[
13, 15]. 4-Dialkylaminopyridinium salts containing 1-alkyl- or alkoxysilyl groups
are useful as PT catalysts in esteri®cation of alkali metal acrylates and meth-
acrylates [16, 17]. So far, no attempts have been reported of their use in reactions
of dihalocarbenes.
In the search for advanced phase-transfer catalysts we explored a number of
quaternary pyridinium salts. The goal of the present work was the synthesis of a
series of quaternary 4-dialkylaminopyridinium halides and a detailed study of their
performance in different PTC reactions of dichlorocarbene, including the in¯uence
of structure on the catalytic activity.
Results and Discussion
Synthesis of 1-alkyl-4-dialkylaminopyridinium halides
In the present work we synthesized a series of quaternary 4-dialkylaminopyridi-
nium halides with 1-alkyl substituents of different chain length. Commercial 4-
dimethylaminopyridine ꢀ1) was used. 4-Morpholinopyridine ꢀ3) was prepared from
its 1-oxide 2 which, in turn, was synthesized from 4-nitropyridine-1-oxide accord-
ing to described procedures [18] ꢀScheme 1).
Quaternization was carried out by re¯uxing pyridines 1 and 3 in acetone with
the corresponding n-alkyl bromides ꢀ4a±i), n-heptylch ol ride ꢀ 4j), or benzylch ol -
ride ꢀ4k) ꢀScheme 2). The reaction products 5a±k, 6c±e, 6g, and 6k appeared as
colourless crystalline or waxy solids, hygroscopic to some extent. Their lipophilic
character becomes more pronounced with the growth of the 1-alkyl chain length.
They were puri®ed by recrystallization from acetonitrile or acetone. IR spectra of
À1
compounds 5a±k, 6c±e, 6g, and 6k showed an absorption band at 1650±1630 cm
Scheme 1

Pyridinium Halides in Dichlorocarbene Reactions
315
Scheme 2. R ˆ C H ꢀ4a, 5a), C H ꢀ4b, 5b), C H ꢀ4c, 5c, 6c), C H ꢀ4d, 5d, 6d), C H ꢀ4e, 4j,
3
7
4
9
5
11
6
13
7 15
5
e, 5j, 6e), C H ꢀ4f, 5f), C H ꢀ4g, 5g, 6g), C H ꢀ4h, 5h), C H ꢀ4i, 5i), CH C H ꢀ4k, 5k, 6k);
8 17 9 19 10 21 12 25 2 6 5
X ˆ Br ꢀ4a±i, 5a±i, 6c±e, 6g), Clꢀ 4j±k, 5j±k, 6k)
‡
ascribed to the CˆN group and con®rming the formation of a quaternary salt. In
1
the H NMR spectra, the signalof the ꢀ-methylene protons ꢀCH -N ) appeared at
‡
2
4.14±4.60 ppm. Reaction times, yields, and physical and spectroscopic data are pre-
sented in the Experimentalsection.
Catalytic properties of 1-alkyl-4-dialkylaminopyridinium halides
The quaternary salts 5a±k, 6c±e, 6g, and 6k were tested as catalysts in three typical
phase-transfer catalysis reactions of dichlorocarbene: dehydration of benzamide
ꢀ
reaction A), N-formylation of diphenylamine ꢀreaction B), and dichlorocyclopro-
panation of styrene ꢀreaction C) ꢀScheme 3). Two commercialPT cata yl sts, TEBA
and tetrabutylammonium bromide ꢀTBAB), as well as 4-dimethylaminopyridine
were tested for the comparison.
Results of the kinetic study are summarized in Table 1. The quaternary salts 5a±
k, 6c±e, 6g, and 6k effectively catalyze reactions A, B, and C. In some instances,
the ef®ciency of those catalysts is higher than that of TEBA and TBAB. Some char-
acteristic points of catalytic performance in different reactions should be pointed
out.
The in¯uence of the structure of the 1-alkyl substituent is particularly evident in
reactions A and B ꢀFig. 1). Higher yields are achieved with catalysts containing an
1-alkyl chain of 5±9 carbon atoms. In the series of 4-dimethylaminopyridinium
Scheme 3

3
16
G.-K. Kupetis et al.
Table 1. PTC Reactions in the presence of 1-alkyl-4-dialkylaminopyridinium halides
a
a
Reaction B Reaction C
a
Catalyst
R
Reaction A
mol% catalyst Yield %
75
b
c
d
Yield %
mol% catalyst Yield %
5
5
5
5
5
5
5
5
5
5
5
5
5
6
6
6
6
6
a
b
c
d
d
e
f
propyl5
butyl5
45
45
47
43
2
2
91
96
90
94
71
98
97
99
87
81
86
62
47
27
24
33
21
9
73
80
91
58
85
77
78
67
73
78
pentyl5
hexyl5
hexyl1
heptyl5
octyl5
2
2
1
53
41
56
39
2
2
g
h
i
nonyl5
decyl5
dodecyl5
heptyl5
benzyl5
benzyl1
pentyl5
hexyl5
heptyl5
nonyl5
benzyl5
2
2
39
2
j
2
k
k
c
d
e
g
k
75
58
95
85
2
1
57
54
1
87
1
83
95
86
59
2
1
65
1
±
7.5
61
0.9
58
1
TEBA
TBAB
DMAP
5
5
2
94
e
26
a
b
Reaction conditions: see Experimental; after 4 h ꢀGC data); after 5 h ꢀGC data); after 3 h ꢀGC
c
d
e
data); 4-dimethylaminopyridine
Fig. 1. In¯uence of alkyl chain length in 1-alkyl-4-dialkylaminopyridinium bromides 5a±i on the
catalytic activity
bromides 5a±i, the maximum activity is displayed by 5d ꢀ6 C atoms) in reaction A
and 5g ꢀ9 C atoms) in reaction B. A similar characteristic phenomenon has already
been observed for quaternary ammonium bromides whose reactivity passes through

Pyridinium Halides in Dichlorocarbene Reactions
317
a maximum at increasing catalyst size. The catalysts have also been found to
reduce the interfacialtension between two phases in such a way that both param-
eters were in correlation [9, 19]. Obviously, a similar rule should hold for quat-
ernary pyridinium salts as well. Moreover, an alternating reactivity order of
catalysts with odd and even numbers of 1-alkyl carbon atoms was observed in the
majority of cases, the former generally are displaying a higher reactivity ꢀFig. 1).
Catalysts with shorter alkyl chains ꢀ3±4 C atoms) obviously are not lipophilic
enough to ensure effective extraction of dichlorocarbene into the organic phase. On
the other hand, quaternary salts with longer alkyl chains ꢀ10±12 C atoms) are
probably less stable at the reaction conditions and are undergoing degradation in
the organic phase. As a proof of this statement, corresponding alkyl chlorides ꢀby-
products of the degradation) were detected in the organic phase ꢀGC analysis), their
concentration growing with time ꢀup to 2.26% with 5h and 4.26% with 5i).
Another phenomenon observed in reaction B was that 5k and 6k ꢀboth with an
1-benzylresidue) are the best cata ly sts; this was not the case in reactions A and C.
Such a behaviour is possibly related to the fact that formylation of secondary
amines under PTC conditions proceeds through a three-step process [20]. Most
probably, the above catalysts better promote one of the steps following the addition
of dichlorocarbene, i.e. the rearrangement to the N-dichloromethyl derivative or
hydrolysis to the ®nal formyl derivative [21].
Characteristic in¯uence of a 1-alkyl chain was less evident in reaction C since
the best catalysts ꢀ5g±j) at a concentration of 2 mol% give nearly a quantitative
yield of 1,1-dichloro-2-phenylcyclopropane. However, a major difference is that,
surprisingly, quaternary salts of 4-morpholinopyridine ꢀ6c±e, 6g, and 6k) display
much lower activity in comparison with 4-dimethylaminopyridinium halides ꢀ5a±
k), although in the reactions A and B the former are as ef®cient as the latter. To
explain that fact, more experimental data are necessary.
A comparison of the catalysts 5e ꢀbromide) and 5j ꢀchloride) allows to evaluate
an in¯uence of the anion on the reactivity. In reactions A and C, 5j displays slightly
lower catalytic activity ꢀTable 1). This can be explained by a lower stability of
Fig. 2. In¯uence of catalyst 5d concentration on benzonitrile yield

3
18
G.-K. Kupetis et al.
‡
À
R N Cl in the organic phase which in the presence of concentrated alkali un-
4
‡
À
dergoes slow degradation via extraction of hydroxide anion ꢀas R N OH ) as
4
stated by Landini et al. [8].
A more detailed kinetic study was carried out by varying the catalyst con-
ꢀ
centration in reaction A ꢀat 50 C). The results showed that the best catalysts are
effective at lower concentrations ꢀ2±3 mol%) as well. As known, TEBA is usually
employed for dehydration of amides at a concentration of 5 mol%. Marked dif-
ferences of the reaction rate are observed within the ®rst two hours of the reaction.
A further increase of the reaction time as well as of the catalyst concentration gives
ꢀ
only a slight improvement ꢀFig. 2). At 30 C, the yield of benzonitrile in the pres-
ence of 5 mol% of 5d was 48% ꢀat 6 h).
Experimental
All melting points are uncorrected. IR spectra ꢀKBr) were recorded on a FT-IR spectrometer Hartmann
1
Braun, Canada. H NMR spectra were recorded on a Tesla BS-567A NMR spectrometer at 80 MHz
&
with TMS as internal standard. GC analysis was performed on a Hewlett Packard instrument HP 5890
equipped with ¯ame-ionization detector and silica capillary column, CP-Sil 8CB ꢀ50 m  0.32 mm
i.d., ®lm thickness 0.25 ꢁm). Elemental analyses ꢀC, H, N) are in satisfactory agreement with cal-
culated values.
4
-Morpholinopyridine ꢀ3; C H N O)
9 12 2
3
A mixture of 18.02 g 2 ꢀ0.1 mol), 19.6 g Zn ꢀ0.3 mol), and 50 cm glacial acetic acid was heated on a
boiling water bath for 3 h. Concentrated aqueous NaOH was added to pH ˆ 8, the mixture was
3
®
ltered, the ®ltrate extracted with 3 Â 50 cm CHCl , dried ꢀK CO ), ®ltered, and evaporated. The
3
2
3
residue was crystallized from acetone to afford 10.35 g ꢀ63%) of 3 as yellowish crystals.
ꢀ
ꢀ
M.p.: 104±105 C ꢀRef. [18]: m.p.: 101±104 C); IR ꢀKBr): ꢂ ˆ 3901, 2959, 2835, 1599,
À1
508 cm ; H NMR ꢀCD OD, ꢃ, ppm): 7.94 ꢀ2H, d, Py-2H), 6.90 ꢀ2H, d, Py-3H), 3.69 ꢀ4H, t, O-
3
1
1
CH ), 3.22 ꢀ4H, t, N-CH ).
2
2
General procedure for the synthesis of 1-alkyl-4-dimethylaminopyridinium halides ꢀ5a±k)
3
To a solution of 1 ꢀ0.02 mol) in 40 cm of acetone, an equimolar amount of alkyl halide was added
dropwise. The reaction mixture was re¯uxed until completion of the reaction ꢀsee below), and the
solid product ꢀpartially hygroscopic) was ®ltered off, washed with cold acetone, dried in vacuo
ꢀP O ), and recrystallized from the speci®ed solvent.
2 5
1
-Propyl-4-dimethylaminopyridinium bromide ꢀ5a; C H BrN )
10 17 2
ꢀ
À1
;
From 1 and 4a ꢀ5 h); yield: 93%; m.p.: 140±142 C ꢀacetone); IR ꢀKBr): ꢂ ˆ 2888, 1631, 1551 cm
1
‡
H NMR ꢀCD CN, ꢃ, ppm): 8.10 ꢀ2H, d, Py-2H), 6.94 ꢀ2H, d, Py-3H), 4.14 ꢀ2H, t, N -CH ), 3.22
3
2
ꢀ6H, s, N-CH ), 1.89 ꢀ2H, m, CH ), 0.93 ꢀ3H, t, CH ).
3 2 3
1
-Butyl-4-dimethylaminopyridinium bromide ꢀ5b; C H BrN )
11 19 2
ꢀ
À1
;
From 1 and 4b ꢀ6 h); yield: 91%; m.p.: 205±208 C ꢀacetone); IR ꢀKBr): ꢂ ˆ 2876, 1647, 1572 cm
1
‡
H NMR ꢀCD CN, ꢃ, ppm): 8.04 ꢀ2H, d, Py-2H), 6.91 ꢀ2H, d, Py-3H), 4.14 ꢀ2H, t, N -CH ), 3.21
3
2
ꢀ6H, s, N-CH ), 1.27 ꢀ4H, m, CH ), 0.97 ꢀ3H, t, CH ).
3 2 3

Pyridinium Halides in Dichlorocarbene Reactions
-Pentyl-4-dimethylaminopyridinium bromide ꢀ5c; C H BrN )
319
1
1
2
21
2
ꢀ
From 1 and 4c ꢀ6 h); yield: 88%; m.p.: 210±212 C ꢀacetonitrile); IR ꢀKBr): ꢂ ˆ 2878, 1640,
À1 ‡
564 cm ; H NMR ꢀCD CN, ꢃ, ppm): 8.06 ꢀ2H, d, Py-2H), 6.92 ꢀ2H, d, Py-3H), 4.14 ꢀ2H, t, N -
3
1
1
CH ), 3.23 ꢀ6H, s, N-CH ), 1.34 ꢀ6H, m, CH ), 0.95 ꢀ3H, t, CH ).
3
2
3
2
1
-Hexyl-4-dimethylaminopyridinium bromide ꢀ5d; C H BrN )
13 23 2
ꢀ
From 1 and 4d ꢀ6 h); yield: 92%; m.p.: 180±182 C ꢀacetonitrile); IR ꢀKBr): ꢂ ˆ 2890, 1650,
À1 ‡
566 cm ; H NMR ꢀCD CN, ꢃ, ppm): 8.07 ꢀ2H, d, Py-2H), 6.92 ꢀ2H, d, Py-3H), 4.16 ꢀ2H, t, N -
3
1
1
CH ), 3.23 ꢀ6H, s, N-CH ), 1.34 ꢀ8H, m, CH ), 0.93 ꢀ3H, t, CH ).
3
2
3
2
1
-Heptyl-4-dimethylaminopyridinium bromide ꢀ5e; C H BrN )
14 25 2
ꢀ
À1
;
From 1 and 4e ꢀ6 h); yield: 74%; m.p.: 145±147 C ꢀacetone); IR ꢀKBr): ꢂ ˆ 2872, 1650, 1567 cm
1
‡
H NMR ꢀꢀCD ) CO, ꢃ, ppm): 8.89 ꢀ2H, d, Py-2H), 7.37 ꢀ2H, d, Py-3H), 4.60 ꢀ2H, t, N -CH ), 3.46
3
2
2
ꢀ6H, s, N-CH ), 1.41 ꢀ10H, m, CH ), 0.93 ꢀ3H, t, CH ).
3 2 3
1
-Octyl-4-dimethylaminopyridinium bromide ꢀ5f; C H BrN )
15 27 2
ꢀ
À1
;
From 1 and 4f ꢀ9 h); yield: 50%; m.p.: 112±113 C ꢀacetone); IR ꢀKBr): ꢂ ˆ 2864, 1641, 1551 cm
1
‡
H NMR ꢀꢀCD ) CO, ꢃ, ppm): 8.84 ꢀ2H, d, Py-2H), 7.30 ꢀ2H, d, Py-3H), 4.61 ꢀ2H, t, N -CH ), 3.47
3
2
2
ꢀ6H, s, N-CH ), 1.43 ꢀ12H, m, CH ), 1.00 ꢀ3H, t, CH ).
3 2 3
1
-Nonyl-4-dimethylaminopyridinium bromide ꢀ5g; C H BrN )
16 29 2
ꢀ
À1
;
From 1 and 4g ꢀ6 h); yield: 93%; m.p.: 108±109 C ꢀacetone); IR ꢀKBr): ꢂ ˆ 2862, 1639, 1564 cm
1
‡
H NMR ꢀꢀCD ) CO, ꢃ, ppm): 8.78 ꢀ2H, d, Py-2H), 7.27 ꢀ2H, d, Py-3H), 4.57 ꢀ2H, t, N -CH ), 3.45
3
2
2
ꢀ6H, s, N-CH ), 1.39 ꢀ14H, m, CH ), 0.97 ꢀ3H, t, CH ).
3 2 3
1
-Decyl-4-dimethylaminopyridinium bromide ꢀ5h; C H BrN )
17 31 2
ꢀ
À1
;
From 1 and 4h ꢀ10 h); yield: 95%; m.p.: 92±95 C ꢀacetone); IR ꢀKBr): ꢂ ˆ 2869, 1644, 1564 cm
1
‡
H NMR ꢀꢀCD ) CO, ꢃ, ppm): 8.76 ꢀ2H, d, Py-2H), 7.28 ꢀ2H, d, Py-3H), 4.58 ꢀ2H, t, N -CH ), 3.46
3
2
2
ꢀ6H, s, N-CH ), 1.40 ꢀ16H, m, CH ), 0.98 ꢀ3H, t, CH ).
3 2 3
1
-Dodecyl-4-dimethylaminopyridinium bromide ꢀ5i; C H BrN )
19 35 2
ꢀ
À1
;
From 1 and 4i ꢀ12 h); yield: 91%; m.p.: 63±64 C ꢀacetone); IR ꢀKBr): ꢂ ˆ 2851, 1653, 1570 cm
1
‡
H NMR ꢀꢀCD ) CO, ꢃ, ppm): 8.84 ꢀ2H, d, Py-2H), 7.38 ꢀ2H, d, Py-3H), 4.60 ꢀ2H, t, N -CH ), 3.47
2
3
2
ꢀ6H, s, N-CH ), 1.37 ꢀ20H, m, CH ), 0.96 ꢀ3H, t, CH ).
3 2 3
1
-Heptyl-4-dimethylaminopyridinium chloride ꢀ5j; C H ClN )
14 25 2
ꢀ
À1
;
From 1 and 4j ꢀ15 h); yield: 32%; m.p.: 100±102 C ꢀacetone); IR ꢀKBr): ꢂ ˆ 2854, 1651, 1568 cm
1
‡
H NMR ꢀCD CN, ꢃ, ppm): 8.10 ꢀ2H, d, Py-2H), 6.94 ꢀ2H, d, Py-3H), 4.14 ꢀ2H, t, N -CH ), 3.22
3
2
ꢀ6H, s, N-CH ), 1.89 ꢀ2H, m, CH ), 0.93 ꢀ3H, t, CH ).
3 2 3

3
20
G.-K. Kupetis et al.
1
-Benzyl-4-dimethylaminopyridinium chloride ꢀ5k; C H ClN )
1
4
17
2
ꢀ
From 1 and 4k ꢀ3 h); yield: 93%; m.p.: 253±254 C ꢀacetonitrile); IR ꢀKBr): ꢂ ˆ 3030, 2993, 2874,
À1
641, 1572 cm ; H NMR ꢀCD CN, ꢃ, ppm): 8.20 ꢀ2H, d, Py-2H), 7.46 ꢀ5H, s, C H ), 6.94 ꢀ2H, d,
3 6 5
1
1
‡
Py-3H), 5.39 ꢀ2H, s, N -CH ), 3.21 ꢀ6H, s, N-CH ).
2
3
General procedure for the synthesis of 1-alkyl-4-morpholinopyridinium
halides ꢀ6c±e, 6g, and 6k)
3
A mixture of 3 ꢀ0.01 mol) and alkyl halide ꢀ0.015 mol) in 40 cm of acetone was re¯uxed for a
maximum of 9 h. If necessary, the solvent was evaporated until the precipitation of a solid product
started which was ®ltered off, dried in vacuo ꢀP O ), and recrystallized from the speci®ed solvent.
2
5
1
-Pentyl-4-morpholinopyridinium bromide ꢀ6c; C H BrN O)
14 23 2
ꢀ
From 3 and 4c ꢀ3 h); yield: 62%; m.p.: 271±272 C ꢀacetonitrile); IR ꢀKBr): ꢂ ˆ 2921, 2853, 1647,
À1 ‡
550 cm ; H NMR ꢀCD CN, ꢃ, ppm): 8.10 ꢀ2H, d, Py-2H), 7.07 ꢀ2H, d, Py-3H), 4.17 ꢀ2H, t, N -
3
1
1
CH ), 3.78 ꢀ4H, t, O-CH ), 3.71 ꢀ4H, t, N-CH ), 1.32 ꢀ6H, m, CH ), 0.95 ꢀ3H, t, CH ).
2
2
2
2
3
1
-Hexyl-4-morpholinopyridinium bromide ꢀ6d; C H BrN O)
15 25 2
ꢀ
From 3 and 4d ꢀ3 h); yield: 90%; m.p.: 190±192 C ꢀacetonitrile); IR ꢀKBr): ꢂ ˆ 2920, 2856, 1645,
À1 ‡
549 cm ; H NMR ꢀCD CN, ꢃ, ppm): 8.09 ꢀ2H, d, Py-2H), 7.07 ꢀ2H, d, Py-3H), 4.15 ꢀ2H, t, N -
3
1
1
CH ), 3.77 ꢀ4H, t, O-CH ), 3.71 ꢀ4H, t, N-CH ), 1.33 ꢀ8H, m, CH ), 0.93 ꢀ3H, t, CH ).
2
2
2
2
3
1
-Heptyl-4-morpholinopyridinium bromide ꢀ6e; C H BrN O)
16 27 2
ꢀ
From 3 and 4e ꢀ8 h); yield: 74%; m.p.: 151±152 C ꢀacetonitrile); IR ꢀKBr): ꢂ ˆ 2926, 2858, 1646,
À1 ‡
545 cm ; H NMR ꢀCD CN, ꢃ, ppm): 8.08 ꢀ2H, d, Py-2H), 7.05 ꢀ2H, d, Py-3H), 4.16 ꢀ2H, t, N -
3
1
1
CH ), 3.77 ꢀ4H, t, O-CH ), 3.70 ꢀ4H, t, N-CH ), 1.34 ꢀ10H, m, CH ), 0.95 ꢀ3H, t, CH ).
2
2
2
2
3
1
-Nonyl-4-morpholinopyridinium bromide ꢀ6g; C H BrN O)
18 31 2
ꢀ
From 3 and 4g ꢀ9 h); yield: 55%; m.p.: 147±149 C ꢀacetone); IR ꢀKBr): ꢂ ˆ 2927, 2860, 1646,
À1 ‡
549 cm ; H NMR ꢀCD CN, ꢃ, ppm): 8.20 ꢀ2H, d, Py-2H), 7.13 ꢀ2H, d, Py-3H), 4.22 ꢀ2H, t, N -
3
1
1
CH ), 3.78 ꢀ4H, t, O-CH ), 3.73 ꢀ4H, t, N-CH ), 1.34 ꢀ14H, m, CH ), 0.94 ꢀ3H, t, CH ).
3
2
2
2
2
1
-Benzyl-4-morpholinopyridinium chloride ꢀ6k; C H ClN O)
16 19 2
ꢀ
From 3 and 4k ꢀ3 h); yield: 66%; m.p.: 289±290 C ꢀacetonitrile); IR ꢀKBr): ꢂ ˆ 3026, 2997, 2847,
À1
645, 1554 cm ; H NMR ꢀCD OD, ꢃ, ppm): 8.24 ꢀ2H, d, Py-2H), 7.39 ꢀ5H, s, C H ), 7.15 ꢀ2H, d,
3 6 5
1
1
‡
Py-3H), 5.36 ꢀ2H, s, N -CH ), 3.76 ꢀ4H, t, O-CH ), 3.72 ꢀ4H, t, N-CH ).
2
2
2
General procedures for PTCreactions
3
Dehydration of benzamide ꢀreaction A): A mixture of benzamide ꢀ0.05 mol), CHCl ꢀ35 cm ),
3
3
catalyst ꢀ1±10 mol%), and 40% aqu. NaOH ꢀ12 cm ) was stirred at 50 C for 4 h.
ꢀ
N-Formylation of diphenylamine ꢀreaction B): A mixture of diphenylamine ꢀ0.05 mol), CHCl
3
3
45 cm ), catalyst ꢀ5 mol%), and 45% aqu. NaOH ꢀ10 cm ) was stirred at 55 C for 5 h.
3
ꢀ
ꢀ

Pyridinium Halides in Dichlorocarbene Reactions
321
Dichlorocyclopropanation of styrene ꢀreaction C): A mixture of styrene ꢀ0.05 mol), CHCl
3
3
35 cm ), catalyst ꢀ1±2 mol%), and 50% aqu. NaOH ꢀ8 cm ) was stirred at 40 C for 3 h.
3
ꢀ
ꢀ
Acknowledgements
Thanks are due to Dr. R. Rekertas for providing the equipment for GC analysis.
References
[
[
[
[
[
[
[
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Received June 27, 2001. Accepted ꢀrevised) September 25, 2001