8
R. K. MOGHADDAM AND G. AGHAPOUR
completion of the aldehyde formation (10 min). Then, PPh3
0.65 g, 2.5 mmol) was added to the reaction mixture and
stirring was continued under reflux until TLC showed the
completion of the reaction (80 min). The solvent was evapo-
rated by rotary evaporator. The crude mixture was subjected
to short column chromatography on silica gel 60
2
(
[
5] (a) Olivan, M.; Caulton, K. G. Cꢁ(Halide) Oxidative Addition
Synthesis of a,a-Dichloroalcohols, a-Hydroxyketones and 1-
Chloro-1-Arylalkylene Oxides via Protonation of Acyllithium
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.
[6] Wolfson, A.; Shokin, O.; Tavor, D. Acid Catalyzes the Synthesis
of Aromatic Gem-Dihalides from Their Corresponding
7] Spaggiari, A.; Vaccari, D.; Davoli, P.; Torre, G.; Prati, F. A Mild
Synthesis of Vinyl Halides and gem-Dihalides Using Triphenyl
(0.063–0.200 mm) using n-hexane as eluent affording 1-
chloro-4-dichloromethylbenzene as product in 95% yield,
1
0
8
.19 g; H-NMR (CDCl , 300 MHz): d 6.59 (s, 1H),
3
.19–8.21 (d, 2H, J ¼ 6.3 Hz), 8.23–8.26 (d, 2H, J ¼ 8.7 Hz)
1
3
ppm; C-NMR (CDCl , 75 MHz): d 70.15, 128.97, 130.00,
3
1
1
34.34, 136.02 ppm; IR (KBr): 3100 (w), 2926 (w), 2854 (w),
595 (m), 1492 (s), 1406 (m), 1090 (s), 1015 (s), 840 (s), 740
ꢁ
1
(s), 689 (s) cm .
[
Conclusions
[
8] Jung, M. E.; Wasserman, J. I. Efficient Synthesis of Vinyl
Chlorides and/or gem-Dichlorides from Ketones by Treatment
In conclusion, the present study has demonstrated that pri-
mary benzylic TMS and THP ethers are converted to gem-
dichlorides via a one-pot two-step procedure using TCCA
and PPh in good to excellent yields. As far as we know,
[9] Kabalka, G. W.; Wu, Z.; Ju, Y. Alkylation of Aromatic
3
this oxidative deprotective method is the first direct method
converting TMS and THP ethers to gem-dichlorides.
Avoidance of the isolation of the aldehyde, availability and
ease of handling of the reagent, operation in neutral media,
excellent selectivity and easy work up are considered as
other advantages of this method.
2
10] Dolbier, W. R. Jr.; Okamoto, M. Preparation of 1,1-
Difluoroalkanes from Aldehydes via 1,1-Bistriflates:
[
[
[
11] Tang, X.; An, J.; Denton, R. M. A Procedure for Apple
Halogenations and Dehydrations Using
a
Polystyrene
7
Acknowledgements
12] Aghapour, G.; Mohamadian, S. One-Pot, Selective and Mild
Conversion of Benzylic Alcohols to gem-Dichlorides Using
Chlorodiphenylphosphine and 2,3-Dichloro-5,6-Dicyanobenzoquinone
The authors gratefully acknowledge the support of this work by the
Damghan University Research Council.
References
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