Y. Liu et al. / Tetrahedron Letters 44 (2003) 1667–1670
1669
Scheme 2.
A typical procedure is as follows: to a mixture of Sm
powder (1 mmol), methyl acrylate (4 mmol) in freshly
distilled N,N-dimethylformamide (DMF, 10 mL), ben-
zoyl chloride (2 mmol, freshly distilled) was added at
room temperature with magnetic stirring under a nitro-
gen atmosphere. The resulting solution turned yellow–
green within 15 min and an exothermic reaction was
observed. After the completion of the reaction (about 1
h), a routine workup of the reaction mixture followed
by column chromatography afforded methyl a,b-diben-
zoylpropionate in 91% yield.
reaction does not occur in THF, indeed, even self-cou-
pling products from the aroyl chloride are rarely
formed.9
In conclusion, the Sm-promoted carbonꢀcarbon double
bond addition of acrylates with aroyl chlorides offers a
facile, efficient, convenient and novel method for the
synthesis of useful polycarbonyl compounds in good to
excellent yields from very simple starting materials.
Furthermore, because the direct use of metallic samar-
ium in organic synthesis without any activator is rarely
reported, this reaction may have additional significance.
A variety of 2-alkoxycarbonyl 1,4-diketones 3 were
obtained in good to excellent yields in the Sm/DMF
system, as shown in Table 1.8 Notably, in this Sm-pro-
moted reaction, when an a-substituted acrylate was
used as the substrate (for example, methyl a-methyl-
acrylate, 2c), the reaction still afforded compounds 3c,
3f, 3i, 3l and 3m smoothly as the major products.
However, the reaction is strongly influenced by the
substituent on the b-position of the acrylate, and
attempts to extend this reaction to methyl cinnamate
(2f), ethyl crotonate (2g) and methyl b-dimethylacrylate
(2h) were in vain. Only substrate 2e, perhaps due to its
double activation, could afford the corresponding
product 3n in 46% yield.
Acknowledgements
We are grateful to the National Natural Science Foun-
dation of China (Project No. 20072033).
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