Download PDF
Synlett 2005(18): 2776-2780  
DOI: 10.1055/s-2005-918927
LETTER
© Georg Thieme Verlag Stuttgart · New York

Highly Diastereoselective and Enantioselective Addition of Organometallic Reagents to a Chiral C 2-Symmetrical Bisimine

Xiaoxia Suna,b, Shuangjun Wanga, Shangjin Suna, Jin Zhua, Jingen Deng*a,b
a Key Laboratory of Asymmetric Synthesis & Chirotechnology of Sichuan Province and Union Laboratory of Asymmetric Synthesis, Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041, P. R. of China
Fax: +86(28)85223978; e-Mail: jgdeng@cioc.ac.cn;
b Graduate School of Chinese Academy of Sciences, Beijing, P. R. of China
Further Information

Publication History

Received 1 August 2005
Publication Date:
10 October 2005 (online)

   Permissions and Reprints All articles of this category
Preview

Abstract

An efficient and straightforward method has been developed for the preparation of enantiomerically enriched C 2-symmetrical vicinal diamines via the addition of organometallic reagents to a chiral bisimine, which gives access to a variety of optically pure ­aromatic and aliphatic C 2-symmetrical vicinal diamines in high yields. The ‘Cram-Davis’ open transition state model is proposed to rationalize the observed stereoselectivities for the addition of ­organolithium reagents to the bisimine.

Key words

chiral 1,2-diamine - chiral bisimine - asymmetric addition - organometallic reagents - asymmetric allylation

8

Procedure for the Synthesis of Bisimine 2.
To a 0.25 M solution of (R)-tert-butanesulfinamide (1, 1.21 g, 10 mmol) in CH2Cl2 (40 mL) was added 6.4 g (40 mmol) of anhyd CuSO4 followed by 40% aq glyoxal (0.72 mL, 5 mmol). The mixture was stirred at r.t. for 2 d. The reaction mixture was filtered through a pad of Celite, and the filter cake was washed well with CH2Cl2. The residue obtained after condensation was purified by chromatography twice. Pure 2 was obtained (0.94 g, 71%) as a pale yellow crystalline solid after recrystallized twice from hexane.

13

X-ray Investigation and Crystal Data. Colorless crystals of (R,R)-3e were grown from Et2O at r.t. The X-ray diffraction data were collected on a Siemens P4 automatic four-circle diffractometer using graphite monochromated Mo-Kα radiation (λ = 0.71073 Å) at r.t. The structure was solved by direct methods using SHELXS-97 and refined by full-matrix least-square calculation on F 2 with SHELXL-97. Crystal data for (R,R)-3e (C24H38N2O3S2): Mw = 466.68, crystal size 0.48 × 0.44 × 0.42 mm, orthorhombic, space group P2 (1)2 (1)2 (1), a = 7.100 (1) Å, b = 19.026 (2) Å, c = 20.197 (2) Å, α = 90°, β = 90°, γ = 90°, V = 2728.36 (56) Å3, Z = 4, D calcd = 1.136 Mg/m- 3, F(000) = 1008, T = 286 (2) K. All non-hydrogen atoms were refined anisotropically, whereas the hydrogen atoms were generated geometrically. Final R indices [I>2σ(I)]: R1 = 0.0415, wR2 = 0.0788. Crystallographic data has been deposited with the Cambridge Crystallographic Data Center supplementary publication no. CCDC-275776. Copies of the data can be obtained free of charge on application to CCDC, 12 Union Road, Cambridge CB2 1EZ, UK [fax: +44 (1223)762910; e-mail: deposit@ccdc.cam.ac.uk].