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. 2013 Jul 1;52(27):6988-91.
doi: 10.1002/anie.201300614. Epub 2013 May 27.

Methylene-bridged bis(imidazoline)-derived 2-oxopyrimidinium salts as catalysts for asymmetric Michael reactions

Andrey E Sheshenev  1 , Ekaterina V Boltukhina, Andrew J P White, King Kuok Mimi Hii
Affiliations
Free PMC article

Methylene-bridged bis(imidazoline)-derived 2-oxopyrimidinium salts as catalysts for asymmetric Michael reactions

Andrey E Sheshenev et al. Angew Chem Int Ed Engl. .
Free PMC article
No abstract available

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Figures

Scheme 1
Scheme 1
Conjugate addition of glycine imine esters (1) to α,β-unsaturated carbonyl compounds.
Figure 1
Figure 1
Effective catalysts containing planar nitrogen atoms for asymmetric Michael reactions.
Figure 2
Figure 2
Structure of (R,R)-5 b as determined by single-crystal X-ray crystallography (nonstereogenic hydrogen atoms omitted).
Scheme 2
Scheme 2
Synthesis of chiral 2-oxopyrimidinium salts (5) from the N-Boc amino acids 6 a–c: a) N-methylmorpholine, ClCO2iBu, R′NH2 (74–96 %). b) AcCl, MeOH, 0 °C→RT. c) LiAlH4, THF, reflux (73–98 % over 2 steps). d) CH2(C(=NH)OEt)2⋅2 HCl (9), CH2Cl2, RT→reflux, (65–100 %). e) 10 % aq. NaOH/CH2Cl2. f) triphosgene, CH2Cl2, NEt3, 0 °C→RT (84–93 % over 2 steps). Boc=tert-butoxycarbonyl.
Scheme 3
Scheme 3
Synthesis of chiral dihydropyrrole derivatives 15.
Scheme 4
Scheme 4
Synthesis of the novel nicotine/proline hybrid (2S,3R,5S)-16: a) 1 a, 5 c (2 mol %), mesitylene, −20 °C, 3 h. b) 1 N HCl, THF, 0 °C, 1.5 h. c) NaBH4, MeOH, 0 °C→RT, 24 h. THF=tetrahydrofuran.
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References

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    1. In recent years, these two terms are increasingly being used interchangeably. By definition, PTC occurs at a liquid–liquid or a solid–liquid interface (which may be considered as a subset of organocatalysis), but this is not always easy to establish.
    1. Ooi T, Marouka K. Angew. Chem. 2007;119:4300–4345. For reviews on the development of asymmetric PTCs, see.
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