3
72 JOURNAL OF CHEMICAL RESEARCH 2011
and then purified. (R)-4 was used as starting material for the
sꢀnthesis of L-carnitine.
through a four step sꢀnthesis. It should be noticed that L-
carnitine and the intermediates in the above sꢀnthetic route are
obtained in good ꢀields and in high chemical and enantiomeric
puritꢀ. The new sꢀnthetic route demonstrates a potential
utilisation of the bꢀ-product (R)-4 in the sꢀnthesis of bioactive
compounds.
4
0–43
A one-pot sꢀnthetic approach
was emploꢀed to convert
(
(
R)-4 to (S)-8. In the presence of a catalꢀtic amount of p-TsOH,
R)-4 reacted with triethꢀl orthoacetate at room temperature
which was followed bꢀ subsequent removal of the volatiles
to give the crude cꢀclic orthoester (R)-7. Subsequent treatment
of (R)-7 with Me SiBr at room temperature for 2h afforded
3
We thank the Science and Technologꢀ Innovation Foundation
for the College Students of Beijing (no. B091000814); the
National Natural Science Foundation of China (NSFC no.
acetoxꢀ bromides (S)-8 in a high ꢀield of 90%.
We performed a selective nucleophilic substitution reaction
of the C -bromide with NaCN at 30 °C for 6 h to afford chlo-
3
2
0972015) and the Natural Science Foundation of Beijing
ronitrile (R)-9 in 90% ꢀield. (R)-9 was treated with aqueous
30,36,37
(no. 2082016) for financial support.
trimethꢀlamine according to the reported method
to
generate the nitrile (R)-6, which was further recrꢀstallised
from ethanol to obtain pure (R)-6 in 75.6% ꢀield. This keꢀ
intermediate (R)-6 was pure enough chemicallꢀ and opticallꢀ,
andcouldbehꢀdrolꢀseddirectlꢀinthepresenceofconcentrated
hꢀdrochloride acid to obtain L-carnitine as the hꢀdrochloride
salt. After purification bꢀ chromatographꢀ on an ion exchange
Received 4 March 2011; accepted 7 May 2011
Paper 1100607 doi: 10.3184/174751911X13090786031880
Published online: 11 July 2011
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30,36,37
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[
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3
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2
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2
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(
0
26 K. Bock, I. Lundt and C. Pedersen, Acta Chem. Scand., Ser. B, 1983, B37,
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8
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[
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4
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1
31
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(
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1
22 (M + 2H, 13).
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25
30
22
2
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D
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3
8
1
3
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3
9
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4
4
1
2
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Conclusion
We developed a new method for efficient conversion of the
bꢀ-product of (R)-3-chloro-1,2-propanediol to L-carnitine
2