Dendritic EDA-Schiff Bases of the Salen-Type

Abstract

Dendronized salicylidene-ethylenediamine (salen) compounds are prepared for the first time through diaza-Cope re­arrangement in which the ethano carbons of the ethylenediamine (EDA) are substituted with two types of dendritic wedges: Fréchet-ether and ester-dendrons. The X-ray analysis of a dendritic salen with ester dendrons is presented.

dendrimers - Schiff bases - diaza-Cope rearrangement - salen ligands - valence isomerisation

References

1 Breinbauer R. Jacobsen EN. Angew. Chem. Int. Ed.  2000,  39:  3604 ; Angew. Chem. 2000, 112, 3750

2 Seebach D. Sellner H. Karjalainen JK. Chem.-Eur. J.  2001,  7:  2873 

For Jacobsen catalysts with various substitution motifs of the ethano bridge, see:

3a Zhang W. Ph.D. Thesis   University of Illinois; USA: 1991. 

3b Irie R. Noda K. Ito Y. Matsumoto N. Tetrahedron Lett.  1990,  31:  7345 

3c Irie R. Noda K. Ito Y. Katsuki T. Tetrahedron Lett.  1991,  32:  1055 

3d Irie R. Ito Y. Katsuki T. Synlett  1991,  265 

3e Irie R. Noda K. Ito Y. Matsumoto N. Katsuki T. Tetrahedron: Asymmetry  1991,  2:  481 

3f Hosoya N. Irie R. Ito Y. Katsuki T. Synlett  1991,  691 

4 O’Connor KJ. Wey SJ. Burrows CJ. Tetrahedron Lett.  1992,  33:  1001 

5 Reddy DR. Thornton ER. J. Chem. Soc., Chem. Commun.  1992,  172 

For early examples of the preparation and use of chiral salen complexes, see:

6a Cesarotti E. Pasini A. Ugo R. J. Chem. Soc., Dalton Trans.  1981,  2147 ; and references cited therein

6b Nakajima K. Kojima M. Fujita J. Chem. Lett.  1986,  1483 

7 Zhang W. Loebach JL. Wilson SR. Jacobsen EN. J. Am. Chem. Soc.  1990,  112:  2801 

8 Jacobsen EN. Zhang W. Muci AR. Ecker JR. Deng L. J. Am. Chem. Soc.  1991,  113:  7063 

9 Zhang W. Jacobsen EN. J. Org. Chem.  1991,  56:  2296 

10a Newkome GR. Moorefield CN. Vögtle F. Dendrimers and Dendrons   Wiley-VCH; Weinheim: 2001.  p.49 

10b Tomalia DA. Fréchet JMJ. Dendrimers and other Dendritic Polymers   John Wiley and Sons; Chichester: 2001. 

11 Tomalia DA. Berry V. Hall M. Hedstand DM. J. Am. Chem. Soc.  1987,  109:  1601 

12 Feuerbach N. Vögtle F. Top. Curr. Chem.  1998,  197:  1 

13 Goldschmitt E. Vögtle F. Chem. Ber.  1976,  109:  1 

14a Goldschmitt E. Vögtle F. Angew. Chem., Int. Ed. Engl.  1973,  12:  767 ; Angew. Chem. 1973, 85, 824

14b Goldschmitt E. Vögtle F. Angew. Chem., Int. Ed. Engl.  1974,  13:  149 ; Angew. Chem. 1974, 86, 520

14c Goldschmitt E. Ph.D. Thesis   Universität Würzburg; Germany: 1975. 

15 Hawker CJ. Fréchet JMJ. J. Am. Chem. Soc.  1990,  112:  7638 

16 Piancatelli G. Synthesis  1982,  245 

17 Bo Z. Zhang X. Wang Z. Yang M. Shen J. Li Y. J. Chem. Soc., Perkin Trans. 1  1997,  2931 

18

General Procedure for diaza-Cope Rearrangements: The amount of 0.29 mmol meso-1,2-bis(2-hydroxyphenyl)-ethylenediamine(1) and 0.594 mmol of the specific formyl substituted dendron 2 or 3 are dissolved in ca. 20 mL MeCN and refluxed for approximately 4 h. In the cold, yellow crystals precipitate. Yield 225 mg (92%) for 6 and 245 mg (94%) for 7, respectively.
Compound 6: Yellow solid; mp 209-211 °C. ¹H NMR (400 MHz, d ₆-acetone): δ = 5.44 (s, 2 H, N-CH _ethylene), 5.74 (s, 8 H, O-CH ₂), 7.14 (d, 4 H, ⁴ J _HH = 1.9 Hz, CH _arom), 7.17 (t, 2 H, ⁴ J _HH = 2.2 Hz, CH _arom), 7.45-7.49 (m, 20 H, ³ J _HH = 1.4 and 2.2 Hz, CH _phenyl), 7.79-7.82 (m, ³ J _HH = 2.0 Hz, CH _arom), 7.91 (s, 2 H, N=CH). ¹³C NMR (100.6 MHz, d ₆-acetone): δ = 75.3 (O-CH₂), 79.2 (CH_ethylene), 102.8, 106.1, 117.4, 119.2 (CH_arom), 121.6 (C _quart,arom C-CN), 128.9, 129.2, 132.2, 133.9 (CH_arom), 141.1 (CH_arom-CH₂), 142.1 (C _quart,arom-C_ethylene), 150.9 (C_quart,arom-OH), 153.5 (C _quart,arom-OCH₂), 164.8 (C=N). FAB-MS: m/z = 845.5 [M⁺], 741.5 [M⁺ - 104], 663.5 [741.5 - C₆H₆ ⁺], 647.5 [741.5 - C₆H₆O⁺], 422.2 [M/2⁺]. Anal. Calcd for C₅₆H₄₈O₆N₂: C, 79.6; H, 5.73; N, 3.32. Found: C, 79.07; H, 5.46; N, 3.38;
Compound 7: Yellow crystals; mp 238-240 °C (acetone). ¹H NMR (400 MHz, d ₆-acetone): δ = 5.31 (s, 2 H, CH _ethylene), 6.83 (m, 2 H, ³ J _HH = 8.4 Hz, ⁴ J _HH = 1.2 Hz, CH _arom), 6.87 (m, 2 H, ⁴ J _HH = 1.2 Hz, ³ J _HH = 7.3 Hz, ³ J _HH = 7.6 Hz, CH _arom), 7.24 (t, 2 H, ³ J _HH = 2.1 Hz, CH _arom), 7.31 (m, 2 H, ⁴ J _HH = 1.6 Hz, ³ J _HH = 7.3 Hz, ³ J _HH = 8.4 Hz, CH _arom), 7.37 (m, 2 H, ³ J _HH = 7.6 Hz, ⁴ J _HH = 1.6 Hz, CH _arom), 7.41 (d, 2 H, ³ J _HH = 2.1 Hz, CH _arom), 7.58-7.59 (m, 8 H, ⁴ J _HH = 1.1 Hz, ³ J _HH = 7.4 Hz, ³ J _HH = 7.9 Hz, CH _arom), 7.72 (m, 2 H, ⁴ J _HH = 1.3 Hz, ³ J _HH = 7.4 Hz, CH _arom), 8.14 (m, 8 H, ⁴ J _HH = 1.3 Hz, ³ J _HH = 7.9 Hz, CH _arom), 8.59 (s, 2 H, N=CH). ¹³C NMR (100.6 MHz, d ₆-acetone): δ = 79.2 (CH_ethylene), 116.3, 117.4, 119.6, 120.2 (CH_arom), 129.7 (C_{quart, arom} C-CN), 130.7, 130.8 (CH_arom), 143.4 (C_{quart, arom} C-CN), 152.5 (C_{quart, arom} C-O), 161.9 (C_{quart, arom} C-O), 161.9 (C_{quart, arom} C-OH), 165.2 (C=N), 168.6 (CO₂), 133.3 (C_{quart, arom} C-CO₂), 133.6, 134.7 (CH_arom). FAB-MS: m/z = 901.2 [M + H⁺], 450.1 [M/2⁺]. MALDI-TOF MS: m/z = 940.0 [M + K⁺], 924.0 [M + Na⁺], 901.0 [M⁺], 797.0 [M - C₇H₄O⁺]. Anal. Calcd for C₅₆H₄₀O₁₀N₂: C, 74.66; H, 4.47; N, 3.11. Found: C, 74.25; H, 4.47; N, 3.20.
X-Ray structure analysis of 7: C₅₆H₄₀N₂O₁₀·2C₃H₆O: yellow crystals, crystal dimension 0.03 × 0.15 × 0.50 mm³; M = 1017.06; triclinic, space group P-1 (No. 2), a = 9.3498 (8), b = 11.7346 (11), c = 12.4850 (13) Å, α = 101.320 (6)°, β = 95.220 (5)°, γ = 96.393 (5)°, V = 1325.8 (2) ų, Z = 1, µ(Mo_{K α}) = 0.0.89 mm^-1, T = 123 (2) K, F(000) = 534. 10418 Reflection up to 2θ_max. = 50° were measured on a Nonius KappaCCD diffractometer with Mo_{K α} radiation, 4134 of which were independent and used for all calculations. The structure was solved by direct methods and refined to F² anisotropically, the H atoms were refined with a riding model. The final quality coefficient wR2 (F²) for all data was 0.2429, with a conventional R(F) = 0.0793 for 321 parameters and 88 restraints.
Crystallographic data (excluding structure factors) for the structures reported in this paper have been deposited with the Cambridge Crystallographic Data Centre as supplementary publication no. CCDC-221830 (9). Copies of the data can be obtained free of charge at www.ccdc.cam.ac.uk/conts/retrieving.html [or from the Cambridge Crystallographic Data Centre, 12, Union Road, Cambrigde CB2 1EZ, UK; fax: [phone]; e-mail: [e-mail]].

19

General Procedure for the Complexation of 7 with Transition Metal Cations M ^²+ : The amount of 0.056 mmol of 7 are solved in 3 mL CH₂Cl₂ and 3 mL of a solution of the corresponding M²⁺-triflate is added at once. The resulting solution is refluxed for approximately 2 h. In the cold, the M²⁺-complexes precipitate. The nickel(II)-triflate gives 36.3 mg (68%) of N,N′-disalicylidene-meso-1,2-bis(3,5-benzoyl-oxydiphenyl)ethylenediaminocobalt(II)(8) and cobalt(II)-triflate gives 29.2 mg (55%) of N,N′-disalicylidene-meso-1,2-bis(3,5-benzoyloxydiphenyl)ethylenediaminonickel
(II)(9).
Compound 8: Greyish green powder. MALDI-TOF MS: m/z = 980.0 [M + Na⁺], 956.9 [M⁺].
Compound 9: Grey powder. MALDI-TOF MS: m/z = 980.0 [M + Na⁺], 957.9 [M⁺], 854.0 [M - C₇H₄O⁺].

20a For intramolecular N-HºO resonance assisted hydrogen bonding, see: Gilli P. Bertolasi V. Ferretti V. Gilli G. J. Am. Chem. Soc.  2000,  122:  10405 

20b For ortho-hydroxy Schiff bases with very short hydrogen bonds, see: Filarowski A. Koll A. Glowiak T. J. Chem. Soc., Perkin Trans. 2  2002,  835 

21 Vögtle F. Heim C. Affeld A. Nieger M. Helv. Chim. Acta  1999,  82:  746 

22 Felder T. Schalley CA. Angew. Chem. Int. Ed.  2003,  42:  2258 ; Angew. Chem. 2003, 115, 2360

23a Moore JS. Xu Z. Macromolecules  1991,  24:  5893 

23b Moore JS. Xu Z. Polym. Prepr. (Am. Soc., Div. Polym. Chem.)  1991,  32:  629 

23c Moore JS. Xu Z. Acta Polym.  1994,  45:  83 

23d Devados C. Bharathi P. Moore JS. J. Am. Chem. Soc.  1996,  118:  9635