Synlett 2009(6): 921-924  
DOI: 10.1055/s-0028-1087965
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

3,4-Methano-β-Proline: A Conformationally Constrained β-Amino Acid

Amiya Kumar Medda, Hee-Seung Lee*
Department of Chemistry and School of Molecular Science (BK21), Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Korea
Fax: +82(42)3502810; e-Mail: hee-seung_lee@kaist.ac.kr;
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Publikationsverlauf

Received 29 November 2008
Publikationsdatum:
16. März 2009 (online)

Abstract

An enantiomerically pure, conformationally constrained β-proline derivative, 3,4-methano-β-proline, was synthesized starting with a readily available bicyclic lactone by using a straightforward synthetic route.

18

HPLC Data for Boc-(3 R ,4 R )-Methano-β-proline Methyl Ester
t R = 13.622 (min), area = 100%; OJ-H, IPA-n-hexane = 5:95; flow rate = 0.4 mL/min, 25 ˚C, λ = 220 nm.

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Crystal Data for Compound 1
C11H17NO4, crystal size: 0.10 × 0.20 × 0.20 mm³, M r = 227.26 g mol, monoclinic, space group P21, λ = 0.71073 Å, a = 6.1437 (8) Å, b = 11.3449 (17) Å, c = 9.3146 (13) Å, α = 90, β = 104.369 (10), γ  = 90, V = 628. 92 (15) ų, Z = 2, ρ calcd = 1.200 g cm, µ  = 0.091 min, T = 293 (2) K, θ range = 3.6-33.2˚; reflections collected: 10063, independent: 4247 (R int = 0.037). The structure was solved by direct methods and refined by full-matrix least-squares on F²; R 1 = 0.0432, wR 2 = 0.1196 [ I > 2σ (I)]; maximal residual electron density: 0.12 e Å. CCDC 710057 contains the supplementary crystallographic data for this structure. These data can be obtained free of charge from the Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.

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HPLC Data for Boc-(3 R )-β-proline Methyl Ester
t R = 20.621 (min), area = 100%; racemic Boc-β-proline methyl ester, t R = 15.985, 20.824 (min). OJ-H, IPA-n-hexane = 5:95; flow rate = 0.4 mL/min, 25 ˚C, λ = 220 nm.