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Synfacts 2014; 10(1): 0076
DOI: 10.1055/s-0033-1340374
Metal-Mediated Synthesis
© Georg Thieme Verlag Stuttgart · New York

Asymmetric Lithiation Trapping of N-Boc Heterocycles

Rezensent(en):
Paul Knochel
,
Nadja M. Barl
Gelardi G, Barker G, O’Brien P, * Blakemore DC. University of York and Pfizer Worldwide Research and Development, Cambridge, UK
Asymmetric Lithiation Trapping of N-Boc Heterocycles at Temperatures above –78 °C.

Org. Lett. 2013;
15: 5424-5427
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Publikationsverlauf

Publikationsdatum:
13. Dezember 2013 (online)

 
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Key words

lithium - asymmetric lithiation - N-Boc heterocycles

Significance

The asymmetric lithiation trapping of various N-Boc heterocycles is disclosed, using s-BuLi and chiral diamines such as (–)-sparteine and (+)-sparteine surrogate at temperatures above –78 °C. The corresponding chiral hetero­cycles are obtained in high yields and with good enantiomeric ratios.


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Comment

The experiments can be conveniently performed, since asymmetric lithiation trappings of, for example, N-Boc pyrrolidine may be conducted at –30 °C, still furnishing the chiral heterocycles with a high enantiomeric ration of about 9:1.


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