6820
J. Org. Chem. 1992,57,6820-6824
24437-41-0;ethyl a-methyl-N-methyl-%pym&acetate,60730-156; 144194-94-5;ethyl diethyl a-methyl-N-methyl-2-pyrrolemalonate, l-methyl-2-p-toluoyl-5-pyrroleacetate, 5207458-5; B(methoxycarbonyl)-2-pyrroleacetonitrile,14419495-6; methyl %indoleacetate, 21422-40-2; 2-indoleacetonitrile, 7210-27-7; ethyl 2furanacetate, 4915-21-3; ethyl 2-thiopheneacetate, 57382-97-5.
Supplementary Material Available: Copy of the ‘42N M R spectrum of diethyl a-methyl-N-methyl-2-pyrrolemalonate (1 page). This material is contained in many librariea on microfiche, immediately follows this article in the microfilm version of the journal, and can be ordered from the ACS see any current masthead page for ordering information.
Solution Conformation of Two C2-SymmetricAmino Derivatives of 1,l’-Binaphthaleneby Circular Dichroism and Liquid Crystal Technique Carlo Rosini, Livia Franzini, and Piero Salvadori* C.N.R. Centro Studi Macromolecole Stereordinate ed Otticamente Attive, Dipartimento di Chimica e Chimica Industriale, via Risorgimento 35,56126 Piaa, Italy
Gian Piero Spada Dipartimento di Chimica Organica ‘A. Mangini”, Universita’ di Bologna, via S. Donato 15, 40127 Bologna, Italy Receiued May 20,1992
The solution conformation of two C2-symmetric 1,l’-binaphthyl compounds (N,N,N’Jv’-tetramethyl-[1,l’binaphthalene]-2,2’-diamine(1) and N,”-dimethyl-[ l,l’-binaphthalene]-2,2’-diamine (2) has been studied by MMX calculations, analysis of the ahrption and CD spectra, and induction of cholesteric mesophasee in nematic liquid crystals. All these methoda indicate that 1 prefers a c h i d conformation and that 2 as~umesa conformation where the two naphthyl moieties are quasi-perpendicular.
ex @6JX
Introduction chart I Studies aimed at determining the structure of Cz-symetric 1,l’-binaphthyl compounds have received consid(R)-1, X = N(CH3)z erable attention in the past years. Such studies have been carried out by circular dichroism (CD) spectro~copy,~~~ X-ray diffraction,’ or liquid crystal techniques? C2-sym(R)-2, X = NHCH, metric binaphthyl compounds play an important role as chiral auxiliaries in asymmetric organic reaction~.~J Conformational studies on these molecules deserve attention because the studies can help to explain the stebeen employed only as a chiral ligand for LiAIHl in the reochemical outcome of the reactions in which these subasymmetric reduction of aromatic ketonea? Binaphthyls stances are employed as chiral auxiliaries. of a given absolute c o n f i i t i o n , for example R,can have It is the aim of this paper to present a detailed conconformations with opposite helicities, depending on the formational study of two diamines with the Cz-symmetric dihedral angle ($1 (Le., the angle Cg-C1-CITcw)between binaphthyl structure, Le., NJv,”Jv’-tetramethyl-[ 1,l’the naphthyl rings (see Figure 1). For 0 < tc, < 90,the binaphthalene]-2,2’-diamine (1) and N,”-dimethylhelicity between the planes containing the naphthyl [l,l’-binaphthalene]-2,2’-diamine (2)(Chart I). Optically moieties is M, and for 90 < tc, < 180, the helicity is P. active 1 has been recently introduced8as a chiral controller for the enantioeelectiveaddition of diethylzinc to aromatic Results and Discussion aldehydes, and satisfactory enantiomeric excesses have Synthesis. The syntheses of compounds 1 and 2 rebeen obtained. Although preliminary chiroptical data for quire optically active [1,1t-binaphthyl]-2,2/-diamine as 1 have been reported,’ the CD spectrum of 1 has not been starting material. This compound w a s prepared and reanalyzed. No data about the chiroptical properties of 2 solved into ita antipodes according to the procedure of have appeared and to the best of our knowledge, it has Miyano and mworkers.l0 The ee of the samplea obtained was determined by HPLC analysis on a Pirkle (R)-N(1) Mielow, K.; Glass,M. A. W.; OBrien, R. E.; Rutkin, P.; Steinberg, (3,5dinitrobenzoyl)phenylglycineCSP column. (R1-l was D. H.; We&, J.; Djerasei, C. J. Am. Chem. SOC.1962,84,1456. obtained from the reaction” of (R)-primary diamine with (2) H a n d , I,; Akimoto, H. J. Am. Chem. SOC.1971,94,4102. formaldehyde/formic acid (Eschweiledlarke reaction) (3) (a) Mason,5.F.; Seal, R H.; hberta, D. R. Tetrahedron 1974,30, 1671. (b) Harada, N.; Nakaniehi, K. Circular dichroic spectroscopy and crystallization from toluene. The ee (>96%) of the Exciton coupling in organic stereochemiutry, Oxford University Press: product was established by ‘H-NMR spectroscopy in the Oxford, U.K., 1983. (4) See,for instance; Harata, K.; Tanaka, J. Bull. Chem. SOC.Jpn. 1973,46,2747. (5) Gottmelli, G.;Spada,G. P.; Bartach, R,Solladie, G.;ZimmermaM, R. J. Org. Chem. 1988,51, 589. (6) Noyori, R.; Takaya, H. Chem. Scr. 1985,25, 83. (7) Noyori, R. Chem. SOC.Rev. 1989,18,187. (8) Rosini, C.;Franzini, L.; Iuliano, A,;Pini, D.; Salvadori, P. Tetrahedron: Asymmetry 1991,2, 363.
(9) Kabuto, K.; Yoshida, T.; Yameguchi, S.; Miyano, S. J. Org. Chem. 1985,50,3013. (10) Miyano, S.; Nawa, M.; Mori, A.; Haehimoto, H. Bull. Chem. SOC. Jpn. 1984,-57, 2171. (11) Benson, S. C.; Cai, P.; Colon, M.; Haiza, M. A.; Tokle8, M.; Snyder, J. K. J. Org. Chem. 1988,53, 5335.
022-3263f 92f 1957-6820$03.00f 0 @ 1992 American Chemical Society
Cz-SymmetricAmino Derivatives of 1,l’-Binaphthalene
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