880
N. Suryakiran et al. / Tetrahedron Letters 48 (2007) 877–881
The halo products were characterized by their 1H NMR
spectral data. For example, the formation of a-halo b-
keto-sulfones led to a downfield chemical shift of the
methylene proton of p-toluenesulfonylacetophenone
(Table 1, entry 1), from d 4.56 to around d 6.50, 6.30,
6.25 in a-iodo, a-bromo and a-chloro p-toluenesulfonyl-
acetophenones, respectively, and no corresponding
signal was present in the spectra of the a,a-dihalo
ature and the mixture stirred for 30 min. After comple-
tion of the reaction as monitored by TLC, the reaction
was extracted into diethyl ether (3 · 20 mL). The
combined organic extracts were dried over anhydrous
sodium sulfate and evaporated to give the correspond-
ing crude products, which was purified on a silica gel
column using hexane:ethyl acetate (9:1) as eluent.
1
p-toluenesulfonylacetophenones. The H NMR spectra
of iodo, bromo, and chloromethyl p-toluylsulfones had
methylene signals at d 4.40, 4.50, and 4.45, respectively.
Further the methine protons of a,a-dibromo, a,a-di-
chloro, a-chloro, a-bromo, a-chloro, a-iodo, and a-
bromo, a-iodo methyl p-toluylsulfones appeared at d
6.15, 6.21, 6.21, 6.50 and 6.61, respectively.
Acknowledgements
The authors are thankful to Dr. J. S. Yadav, Director of
IICT, for his constant encouragement and DOD, DBT
and CSIR New Delhi, for financial support.
In conclusion, we have reported in this Letter a facile
route to a-halo b-keto-sulfones using potassium halide
(halogen = I, Br, Cl) in the presence of hydrogen
peroxide, and the synthesis of a,a-symmetrical and
asymmetrical dihalo b-keto-sulfones, and a-halo, a-
alkyl b-keto-sulfones and their base induced cleavage
products.
References and notes
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Suryakiran
