Facile conversion of aldehydes and ketones to gem-dichlorides using chlorodiphenylphosphine/N-chlorosuccinimide as a new and neutral system

Article abstract of DOI:10.1080/00397910802271271

Aldehydes and ketones are easily converted to their corresponding gem-dichlorides using a mixture of chlorodiphenylphosphine and N-chlorosuccinimide (ClPPh2/NCS) in dichloromethane under neutral conditions and at room temperature. Copyright Taylor & Francis Group, LLC.

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Facile Conversion of
Aldehydes and Ketones
to gem-Dichlorides Using
Chlorodiphenylphosphine/N-
Chlorosuccinimide as a New
and Neutral System
a
a
Ghasem Aghapour & Asieh Afzali
a
School of Chemistry, Damghan University of Basic
Sciences, Damghan, Iran
Published online: 20 Oct 2008.
To cite this article: Ghasem Aghapour & Asieh Afzali (2008) Facile Conversion
of Aldehydes and Ketones to gem-Dichlorides Using Chlorodiphenylphosphine/N-
Chlorosuccinimide as a New and Neutral System, Synthetic Communications: An
International Journal for Rapid Communication of Synthetic Organic Chemistry, 38:22,
4023-4035, DOI: 10.1080/00397910802271271
To link to this article: http://dx.doi.org/10.1080/00397910802271271
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1
Synthetic Communications , 38: 4023–4035, 2008
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397910802271271
Facile Conversion of Aldehydes and Ketones to
gem-Dichlorides Using Chlorodiphenylphosphine/
N-Chlorosuccinimide as a New and Neutral
System
Ghasem Aghapour and Asieh Afzali
School of Chemistry, Damghan University of Basic Sciences,
Damghan, Iran
Abstract: Aldehydes and ketones are easily converted to their corresponding
gem-dichlorides using a mixture of chlorodiphenylphosphine and N-chlorosucci-
nimide (ClPPh
temperature.
2
=NCS) in dichloromethane under neutral conditions and at room
Keywords: Aldehyde,
N-chlorosuccinimide
chlorodiphenylphosphine,
gem-dichloride,
ketone,
The conversion of aldehydes and ketones to the corresponding gem-
dichlorides is a very important transformation in organic synthesis
because these compounds can serve as precursors to transition-metal
[1]
alkylidenes for carbonyl olefination and also the product dichloroaryl-
[
methanes are of value in the pharmaceutical and agricultural industries.
2]
[
Generally, PCl is used to generate geminal dichlorides. Other methods
3]
5
[
include the use of SOCl =N,N-dimethylformamide (DMF), WCl6,
4]
[5,6]
2
[
BCl3, PPh =CCl , alkylboron chloride derivatives, acid halides in
7]
[8]
[9]
3
4
[10]
[11]
the presence of acid catalysts,
reagents. Also, synthesis of gem-dichlorides from the reaction of hydra-
and (PhO) P=Cl ,
as chlorination
3
2
zones prepared by the treatment of aldehydes and ketones with hydrazine
Received June 8, 2008.
Address correspondence to Ghasem Aghapour, School of Chemistry,
Damghan University of Basic Sciences, Damghan 3671641167, Iran. E-mail:
Gh_Aghapour@dubs.ac.ir
4
023

4024
G. Aghapour and A. Afzali
˚
hydrate in the presence of 4-A molecular sieves with copper(II) chloride–
[
12]
lithium tert-butoxide as an oxidizing agent, has been reported, and also
in a minor modification of this procedure, this transformation has been
carried out via treatment of aldehyde- and ketone-derived N-tert-butyldi-
[
13]
methylsilylhydrazones with CuCl and a catalytic amount of Sc(OTf) .
2
3
However, these methods contain some disadvantages such as use of
toxic reagents, operation at high temperature or in acidic conditions, long
reaction times, applicability for either aldehydes or ketones, unsuitability
for carbonyl compounds containing enolizable hydrogens, formation of
undesired products, and low yields. Consequently, there is a need for
the development of new methods within neutral media that are more con-
venient for this important synthetic transformation.
In continuation of our work on the new applications of trivalent
phosphorus in organic synthesis,
[14]
we now report a facile conversion
of both aldehydes and ketones to their corresponding gem-dichlorides
using a mixture of chlorodiphenylphosphine=N-chlorosuccinimide (ClPPh2=
NCS) under neutral conditions (Scheme 1).
First, we selected p-chlorobenzaldehyde as an example and optimized
the reaction conditions for its conversion to 1-chloro-4-dichloromethyl-
benzene 1 using ClPPh =N-chlorosuccinimide (NCS). In this connection,
2
we found that the solvent-free use of ClPPh and NCS simultaneously is
2
highly exothermic and vigorous for this purpose. Thus, for ease and mild
performance of this transformation, we carried out it in CH Cl as
2
2
solvent. The results of this study are shown in Table 1. Comparison of
entries 2 and 3 show that heating the reaction mixture does not highly
improve the yield or rate of this transformation. Also, this conversion
was unsuccessful by ClPPh (4 eq.) in the absence of NCS even under
2
heating (Table 1, entries 5 and 6). In these cases, the desired gem-dichlor-
ide 1 was obtained in only 20% yield at room temperature and 25% yield
under reflux conditions after 23 h.
Scheme 1. Conversion of aldehydes and ketones to gem-dichlorides using
chlorodiphenylphosphine=N-chlorosuccinimide.

gem-Dichlorides
4025
Table 1. Conversion of p-chlorobenzaldehyde to its corresponding gem-
dichlorides 1 in CH Cl in various conditions
2
2
a
ꢀ
Entry
Reagents
Molar ratio
Time (h)
Temp. ( C)
Yield (%)
1
2
3
4
5
6
7
8
9
ClPPh
ClPPh =NCS
2
=NCS
1=1=1
1=1.5=1.5
1=1.5=1.5
1=2=2
1=4
24
17
9
2
23
23
4.5
4.5
23
rt
rt
reflux
rt
rt
reflux
rt
reflux
rt
10
20
30
90
20
25
2
ClPPh
ClPPh
ClPPh
2
=NCS
2
=NCS
2
ClPPh2
1=4
b
ClPPh
ClPPh
PPh =NCS
2
=NCS
=NCS
1=2=2
1=2=2
1=2=2
20
b
2
20
40
3
a
Molar ratio is related to aldehyde=tertiary phosphine=NCS.
b
This reaction was carried out in acetonitrile as solvent.
In addition, increasing the molar ratio of the mixed reagent (ClPPh2=
NCS) causes the increase of both yield and rate of this reaction (Table 1,
entries 1, 2, and 4) so that the best result was obtained in the case of entry 4:
1 was obtained in 90% yield after 2 h at room temperature. Also, this con-
version was unsuccessful in acetonitrile instead of dichloromethane
as solvent (Table 1, entries 7 and 8). In this case, 1 was produced
using ClPPh =NCS (2:2) in only 20% yield after 4.5 h even under reflux
conditions.
2
Also, we found that performing this transformation using PPh =NCS
3
instead of ClPPh =NCS requires a longer reaction time and affords a
2
lower yield of 1 (Table 1, entry 9). This result shows the better efficiency
of ClPPh =NCS for this transformation. Thus, we extended the opti-
2
mized reaction conditions (Table 1, entry 4) with variable molar ratio
of the present mixed reagent for conversion of other aldehydes and
ketones to their corresponding gem-dichlorides. The results are shown
in Table 2.
As shown in this table, aldehydes and ketones are conveniently con-
verted to their corresponding gem-dichlorides using ClPPh =NCS in
2
CH Cl at room temperature in good to excellent yields. In addition,
2
2
the yield and rate of this transformation for aldehydes are more than

4
026

4
027

4
028

gem-Dichlorides
4029
ketones because of steric and electronic factors. Also, the conversion of 3-
phenylpropanal as an aldehyde containing enolizable hydrogen to 1,1-
dichloro-3-phenylpropane 9 was successfully carried out using the present
[
7]
method (Table 2, entry 9), contrary to the previously reported method.
The lower yields in the case of the ortho isomer of substituted aromatic
aldehydes may be due to steric hindrance of the substituent (Table 2,
entries 3 and 5).
However, we found that the conversion of p-methoxybenzaldehyde to
its corresponding gem-dichloride was unsuccessful using the presented
method. In this transformation using ClPPh =NCS (2.5:2.5), 80% of the
2
starting material remained after 10 h. This observation is probably related
to the methoxy group in the para position, which decreases the stability of
[
16]
this product toward hydrolysis in accordance with the literature.
0
In the case of 4 -nitroacetophenone, a mixture of two products con-
taining the corresponding gem-dichloride 10 and 1-(1-chloroethenyl)-4-
nitrobenzene (p-O NPhCCl ¼ CH ) 13 were isolated from the reaction
2
2
mixture. The NMR spectra of these mixed products (in CDCl ) were
3
1
recorded and revealed that the characteristic C resonance for carbonyl
3
1
3
group was absent but that new C NMR resonances were present at
6.37 ppm (CCl group of 10) and 116.83 ppm (¼ CH group of 13)
8
2
2
1
and also new H NMR resonances at 2.56 ppm (s) for methyl group of
0, 5.73 ppm (d, J ¼ 2.1 Hz) and 5.94 ppm (d, J ¼ 2.2 Hz) both for
1
(
¼ CH ) group of 13. Also, the molar ratio of 1:1 was obtained for these
2
products (10, 13) from this study (Table 2, entry 10).
In addition, the possibility of preparing of mixed gem-dihalides was
investigated via exchanging NCS with N-bromosuccinimide (NBS). For this
purpose, benzaldehyde was treated with a mixture of ClPPh =NBS (2:2)
2
in CH Cl at room temperature. After completion of the reaction (6 h),
2
2
the solvent was evaporated. A mixture of products was obtained using col-
umn chromatography. NMR and gas chromatography (GC)–mass analysis
of this mixture showed the formation of different gem-dihalides containing
dibromomethylbenzene 12 and bromochloromethylbenzene 14 in a 4:1 ratio
together with a trace amount of dichloromethylbenzene 7 in 75% yield
(Table 2, entry 12).
On the basis of differences between reaction rates of aldehydes
and ketones in the present method, we studied the possibility of the
conversion of aldehydes in the presence of ketones in a binary mixture.
In treatment of a binary mixture containing p-nitrobenzaldehyde and
0
4
temperature, p-nitrobenzaldehyde was completely converted to 4 but
-nitroacetophenone (1:1) with ClPPh =NCS (3:3) in CH Cl at room
2 2 2
0
4 -nitroacetophenone completely remained after 35 min, indicating that
this new method selectively converts aldehydes to their corresponding
gem-dichlorides in the presence of ketones (Scheme 2).

4030
G. Aghapour and A. Afzali
Scheme 2. Selective conversion of p-nitrobenzaldehyde to its corresponding gem-
0
dichloride 4 in the presence of 4 -nitroacetophenone in a binary mixture (1:1)
2
using ClPPh =NCS.
Although the exact mechanism of this reaction is not clear, on the
on the reaction of Ph P and NCS, the formation
3
[14a,b]
basis of the reports
of complex (A) can be assumed from the reaction of ClPPh and NCS
2
with concomitant releasing of the chloride anion (Scheme 3).Treatment
of aldehydes or ketones with (A) could produce (B), which later reacts
with the chloride anion to give the intermediate (C). Finally, subsequent
attack of the second chloride anion to this intermediate affords the
desired gem-dichloride. The major deriving force for this reaction could
well be the formation of a double bond between oxygen and oxophilic
phosphorus (P ¼ O).
In conclusion, the present investigation has demonstrated that the
use of ClPPh =NCS offers a simple, novel, and convenient method,
2
avoiding the use of molecular halogen with its harsh handling for the con-
version of aldehydes and ketones to their corresponding gem-dichlorides.
Availability, ease of handling, and low cost of the reagent; excellent selec-
tivity; easy workup; operation at room temperature in neutral media; and
applicability for aldehydes, ketones, and also carbonyl compounds con-
taining enolizable hydrogens can be considered as other advantages of
this method. Further studies toward the other applications of this reagent
in organic synthesis are in progress in our laboratory.
EXPERIMENTAL
Solvents, reagents, and chemicals were obtained from Merck (Germany)
and Fluka (Switzerland) chemical companies. Products are known com-
poundsand were characterized by comparison of their physical data, IR,
NMR, and mass spectra with those prepared according to literature
procedures. Fourier transform infrared (FT-IR) spectra were recorded
on a Perkin-Elmer RXI spectrophotometer. NMR spectra were recorded

gem-Dichlorides
4031
on a Brucker Avance DRX-500 spectrometer. Mass spectra were deter-
mined on a HP 5973 msd at 70 ev. Thin-layer chromatography (TLC)
was carried out on silica-gel 254 analytical sheets obtained from Fluka.
Typical Procedure for the Conversion of 3-Nitrobenzaldehyde
to 1-dichloromethyl-3-nitrobenzene (2)
To a flask containing a stirring mixture of ClPPh (0.368 ml, 2 mmol) and
2
NCS (0.268 g, 2 mmol) in CH Cl (5 ml), 3-nitrobenzaldehyde (0.151 g,
2
2
1 mmol) was added at room temperature. The stirring was continued
until TLC showed the completion of the reaction (1.75 h). The
solvent was evaporated. Compound 2 was obtained after short column
Scheme 3. Mechanism of the conversion of aldehydes and ketones to gem-
dichlorides using ClPPh =NCS.
2

4032
G. Aghapour and A. Afzali
chromatography of the crude mixture on silica gel 60 (0.063–0.200 mm)
using petroleum ether–ethyl acetate (40:1) as eluent in 82% yield,
[17]
ꢀ ꢀ
0
.169 g; mp 64–65 C (lit. 65 C).
Data
-Dichloromethyl-4-nitrobenzene (4)
1
ꢀ
[17]
ꢀ
46 C); H NMR (CDCl , 500 MHz): d
3
1
Yield 73%; mp 45–46 C (lit.
.77 (s, 1H), 7.74–7.77(m, 2H), 8.24–8.27 (m, 2H) ppm; C NMR
CDCl , 125.77 MHz): d 70.26, 124.55, 127.81, 146.67, 148.97 ppm; FT-
1
3
6
(
3
IR (neat): 3110 (w), 3081 (w), 2926 (m), 2857 (m), 1609 (m), 1531 (s),
1
ꢁ1
494 (m), 1348 (s), 1110 (m), 863 (m), 823 (s), 767 (s), 713 (s) cm ; mass
3
7
spectra m=e: 209 (M þ 4), 207 (M þ 2), 205 (M), 172 (M þ 4– Cl and
3
5
37
35
M þ 2– Cl, 34.46%), 170 (M þ 2– Cl and M– Cl, 100%), 163 (M þ 4–
NO ), 161 (M þ 2–NO ), 159 (M–NO ).
2
2
2
1
-Dichloromethyl-2-nitrobenzene (3)
ꢀ
[18]
ꢀ
1
Yield 60%; mp 26–27 C (lit. 26–27 C); H NMR (CDCl , 500MHz): d
3
7
.55–7.58 (m, 1H), 7.56 (s, 1H), 7.74–7.78 (m, 1H), 7.97–7.99 (dd, 1H,
13
J¼ 8.2, 0.91 Hz), 8.18–8.20 (dd, 1H, J ¼ 7.97, 1Hz) ppm; C NMR (CDCl ,
3
125.77 MHz): d 66.36, 125.04, 130.34, 131.16, 134.65, 135.25, 146.51 ppm.
1
-Chloro-4-dichloromethylbenzene (1)
1
Yield 90%; H NMR (CDCl , 500 MHz): d 6.67 (s, 1H), 7.37–7.39 (m,
3
1
3
2
1
2
H), 7.50–7.52 (m, 2H) ppm; C NMR (CDCl , 125.77 MHz): d 71.24,
27.96, 129.42, 136.29, 139.31 ppm; FT-IR (neat): 3100 (w), 2926 (m),
3
854 (m), 1598 (m), 1492 (s), 1406 (m), 1090 (s), 1015 (m), 840 (s), 740
ꢁ
s), 689 (s) cm . Anal. calcd. for C H Cl : C, 43.01; H, 2.58. Found:
7 5 3
1
(
C, 43.04; H, 2.56.
1
-Chloro-2-dichloromethylbenzene (5)
ꢀ
[17]
ꢀ
1
Yield 68%; bp 228–229 C (lit. 228.5 C); H NMR (CDCl , 500 MHz):
3
d 7.17 (s, 1H), 7.30–7.40 (m, 3H), 7.93–7.95 (dd, 1H, J ¼ 7.8, 1.41 Hz)
1
3
ppm; C NMR (CDCl , 125.77 MHz): d 68.37, 128.19, 129.26, 129.93,
3
1
31.30, 131.42, 138.04 ppm.

gem-Dichlorides
4033
1
-Bromo-4-dichloromethylbenzene (6)
1
Yield 75%; H NMR (CDCl , 500 MHz): d 6.66 (s, 1H), 7.43–7.46 (m,
3
1
3
2
1
3
H), 7.53–7.55 (m, 2H) ppm; C NMR (CDCl , 125.77 MHz): d 71.34,
24.51, 128.24, 132.43, 139.78 ppm. Anal. calcd. for C H BrCl : C,
5.04; H, 2.10. Found: C, 35.06; H, 2.06.
3
7
5
2
Dichloromethylbenzene (7)
ꢀ
[17]
ꢀ
205.2 C); mass spectra m=e: 164
Yield 71%; bp 205–206 C (lit.
(
3
7
M þ 4, 0.9%), 162 (M þ 2, 5.7%), 160 (M, 8.8%), 127 (M þ 4– Cl or
3
5
37
35
M þ 2– Cl, 33%), 125 (M þ 2– Cl or M– Cl, 100%), 90 (M þ 4–2Cl,
M þ 2–2Cl or M–2Cl, 4.9%).
1
-Dichloromethyl-4-methylbenzene (8)
ꢀ
[19]
ꢀ
1
Yield 65%; mp 47–48 C (lit. 48.5 C); H NMR (CDCl , 500 MHz): d
3
2
2
1
.38 (s, 3H), 6.69 (s, 1H), 7.20–7.22 (d, 2H, J ¼ 7.99 Hz), 7.45–7.47 (d,
1
3
H, J ¼ 8.14 Hz) ppm; C NMR (CDCl , 125.77 MHz): d 21.67, 72.27,
3
26.43, 129.81, 138.09, 140.53 ppm.
1
,1-Dichloro-3-phenylpropane (9)
1
Yield 72%; H NMR (CDCl , 500 MHz): d 2.50–2.54 (m, 2H), 2.87–2.90
3
(
t, 2H, J ¼ 7.5 Hz), 5.66–5.68 (t, 1H, J ¼ 6.2 Hz), 7.20–7.25 (m, 3H), 7.30–
1
3
7
1
1
1
.33 (m, 2H) ppm; C NMR (CDCl , 125.77 MHz): d 32.54, 45.42, 73.12,
3
26.92, 128.88, 129.10, 139.78 ppm; mass spectra m=e: 192 (M þ 4, 4%),
3
5
37
90 (M þ 2, 22%), 188 (M, 34.17%), 155(M þ 2– Cl and M þ 4– Cl),
3
5
37
53 (M– Cl and M þ 2– Cl), 91 (M–CH CHCl , 100%). Anal. calcd.
2
2
for C H Cl : C, 57.17; H, 5.33. Found: C, 57.14; H, 5.35.
9
10
2
Dibromomethylbenzene (12)
Mass spectra m=e: 252 (M þ 4, 1%), 250 (M þ 2, 2%), 248 (M, 1%), 171
8
1
79
81
79
(
9
M þ 4– Br or M þ 2– Br, 100%), 169 (M þ 2– Br or M– Br, 100%),
0 (M þ 4–2Br, M þ 2–2Br or M–2Br, 33.1%).
Bromochloromethylbenzene (14)
Mass spectra m=e: 208 (M þ 4, 0.15%), 206 (M þ 2, 0.67%), 204 (M,
3
7
35
37
0
.5%), 171 (M þ 4– Cl or M þ 2– Cl, 3.3%), 169 (M þ 2– Cl or

4034
G. Aghapour and A. Afzali
3
5
81
79
81
M– Cl, 3.3%), 127 (M þ 4– Br or M þ 2– Br, 33.6%), 125 (M þ 2– Br
7
9
or M– Br, 100%), 90 (M þ 4–Br–Cl, M þ 2–Br–Cl or M–Br–Cl, 8.8%).
ACKNOWLEDGMENT
We gratefully acknowledge the support of this work by Damghan
University of the Basic Sciences Research Council.
REFERENCES
1
. (a) Piotrowski, A. M.; Malpass, D. B.; Boleslawski, M. P.; Eisch, J. J. Alky-
lenation with geminal dialuminoalkane reagents: The synthesis of olefins
from ketones. J. Org. Chem. 1988, 53, 2829–2835; (b) Takai, K.; Shinomiya,
N.; Kaihara, H.; Yoshida, N.; Moriwake, T.; Utimoto, K. Transformation of
aldehydes into (E)-1-alkenylboronic esters with a geminal dichromium
reagent derived from a dichloromethylboronic ester and CrCl
995, 963–964; (c) Takeda, T.; Sasaki, R.; Fujiwara, T. Carbonyl olefination
by means of a gem-dichloride-Cp Ti[P(OEt) ] system. J. Org. Chem. 1998,
2
. Synlett
1
2
3 2
63, 7286–7288.
2
. (a) Hill, R. A. In Comprehensive Organic Functional Group Transformations;
Pergamon Press: New York, 1995; vol. 4, p. 11; (b) Halpert, J. R.; Balfour, C.;
Miller, N. E.; Kaminisky, L. S. Dichloromethyl compounds as mechanism-
based inactivators of rat liver cytochromes P-450 in vitro. Mol. Pharmacol.
1986, 30, 19–24; (c) Kabalka, G. W.; Li, N.-S.; Yu, S. Synthesis of a,a-
dichloroalcohols, a-hydroxyketones, and 1-chloro-1-arylalkylene oxides via
protonation of acyllithium reagents. J. Organomet. Chem. 1999, 572, 31–36;
(
d) Olivan, M.; Caulton, K. G. C-(Halide) oxidative addition routes to ruthe-
nium carbenes. Inorg. Chem. 1999, 38, 566–570; (e) Ishino, Y.; Mihara, M.;
Nishihama, S.; Nishiguchi, I. Zinc metal–promoted stereoselective olefination
of aldehydes and ketones with gem-dichloro compounds in the presence of
chlorotrimethylsilane. Bull. Chem. Soc. Jpn. 1998, 71, 2669–2672.
. Armstrong, D. E.; Richardson, D. H. The Reimer–Tiemann reaction.
J. Chem. Soc. 1933, 496–500.
. Newman, M. S.; Sujeeth, P. K. Conversion of aromatic and a, b-unsaturated
aldehydes to dichlorides by thionyl chloride and dimethylformamide. J. Org.
Chem. 1978, 43, 4367–4369.
3
4
5
6
7
. Firouzabadi, H.; Shiriny, F. New applications of tungsten hexachloride
(
bisubstitution reactions. Tetrahedron 1996, 52, 14929–14936.
. Jung, M. E.; Wasserman, J. I. Efficient synthesis of vinyl chlorides and=or
gem-dichlorides from ketones by treatment with tungsten hexachloride.
Tetrahedron Lett. 2003, 44, 7273–7275.
. Kabalka, G. W.; Wu, Z. Conversion of aromatic aldehydes to gem-
dichlorides using boron trichloride: A new highly efficient method for prepar-
ing dichloroarylmethanes. Tetrahedron Lett. 2000, 41, 579–581.
WCl ) in organic synthesis: Halo-de-hydroxylation and dihalo-de-oxo-
6

gem-Dichlorides
4035
8
. Vinczer, P.; Struhar, S.; Novak, L.; Szantay, C. Chemistry of the Wittig
reaction, IV: Simple conversion of aldehydes to 1,1-dichloroalkane and
,1-dichloro-1-alkene derivatives, useful intermediates for the synthesis of
1
acetylenic compounds. Tetrahedron Lett. 1992, 33, 683–686.
. Kabalka, G. W.; Wu, Z.; Ju, Y. Alkylation of aromatic aldehydes with alkyl-
boron chloride derivatives. Tetrahedron 2001, 57, 1663–1670.
9
1
1
1
1
0. Wolfson, A.; Shokin, O.; Tavor, D. Acid catalyzes the synthesis of aromatic
gem-dihalides from their corresponding aromatic aldehydes. J. Mol. Catal.
A: Chemical 2005, 226, 69–76.
1. Spaggiari, A.; Vaccari, D.; Davoli, P.; Torre, G.; Prati, F. A mild synthesis of
vinyl halides and gem-dihalides using triphenylphosphite-halogen-based
reagents. J. Org. Chem. 2007, 72, 2216–2219.
2. Takeda, T.; Sasaki, R.; Yamauchi, S.; Fujiwara, T. Transformation of
ketones and aldehydes to gem-dihalides via hydrazones using copper(II)
halides. Tetrahedron 1997, 53, 557–566.
3. Furrow, M. E.; Myers, A. G. Practical procedures for the preparation of
N-tert-butyldimethylsilylhydrazones and their use in modified Wolf–Kishner
reductions and in the synthesis of vinyl halides and gem-dihalides. J. Am.
Chem. Soc. 2004, 126, 5436–5445.
1
4. (a) Iranpoor, N.; Firouzabadi, H.; Aghapour, G. A facile conversion of thiols
to alkyl halides by triphenylphosphine=N-halosuccinimides. Synlett 2001, 7,
1176–1178; (b) Iranpoor, N.; Firouzabadi, H.; Aghapour, G. A rapid and
facile conversion of primary amides and aldoximes to nitriles and ketoximes
to amides with triphenylphosphine and N-chlorosuccinimide. Synth. Com-
mun. 2002, 32, 2535–2541; (c) Aghapour, G.; Amirabadi, M. A facile and
high efficient synthesis of nitriles from aldoximes and primary amides with
a
(
4
mixture of triphenylphosphine=2,3-dichloro-5,6-dicyanobenzoquinone
PPh =DDQ) under neutral conditions. Indian J. Chem., Sect. B. 2007,
6B, 649–652.
3
1
5. Olah, G. A.; Comisarow, M. B. Stable carbonium ions, LXXXI: Alkyl (aryl)
halocarbonium ions and haloarylcarbonium ions. J. Am. Chem. Soc. 1969,
91, 2955–2961.
1
1
1
6. Lansinger, J. M.; Ronald, R. C. Reactions of aromatic aldehydes with boron
halides. Synth. Commun. 1979, 9, 341–349.
7. Weast, R. C. CRC Handbook of Chemistry and Physics, 47th ed.; Chemical
Rubber Co.: Cleveland, Ohio, 1966–1967.
8. Makosza, M.; Owczarczyk, Z. Dihalomethylation of nitroarenes via vicarious
nucleophilic substitution of hydrogen with trihalomethyl carbanions. J. Org.
Chem. 1989, 54, 5094–5100.
1
9. Lide, D. R. CRC Handbook of Chemistry and Physics, 78th ed.; CRC Press:
New York, 1997–1998.