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Synlett 2005(15): 2373-2375  
DOI: 10.1055/s-2005-872260
LETTER
© Georg Thieme Verlag Stuttgart · New York

The Synthesis of Homochiral Hybrid Diamines Derived from 1,1′-Binaphthyl-2,2′-diamine and α-Amino Acids

Bartłomiej Kowalczyka,b, Aldona Tarnowskaa, Łukasz Weselińskia, Janusz Jurczak*a,b
a Department of Organic Chemistry, Warsaw University, Pasteura 1, 02-093, Warsaw, Poland
b Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
Fax: +48(22)6326681; e-Mail: jurczak@icho.edu.pl;
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Publication History

Received 29 June 2005
Publication Date:
03 August 2005 (online)

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Abstract

A convenient procedure for the preparation of homochiral diamines is presented. Coupling of racemic 1,1′-binaphthyl-2,2′-diamine with natural N-protected amino acids afforded the corresponding diastereomeric precursors which, following chromatographic separation and deprotection, gave the desired products in good yields. These compounds, called herein hybrid compounds, possess two different stereogenic elements, i.e., the centre containing the l-amino acid residues and the C 2 axis, resulting from the 1,1′-binaphthyl moiety.

Key words

synthesis - binaphthyl moiety - homochiral diamines - diastereomers - axial chirality - amino acids

4

General procedure for synthesis and resolution of compounds of type 2
To a solution of N-Boc protected amino acid (2.2 mmol) in anhyd CH2Cl2, was added DCC (2.2 mmol), and the mixture was stirred at r.t. for 30 min. Then rac -1 (1 mmol) was added in one portion. After 48 h the precipitate was filtered through celite and rinsed with cold CH2Cl2. The filtrate was evaporated in vacuo and the residue was purified by column chromatography (hexane-EtOAc, 30-60%) to give products 2a-d.
Selected analytical data for (S)-2a: Yield 35%, colorless solid as a foam. Mp 70-75 °C. [α]D 25 -95.7 (c 0.9, CH2Cl2). 1H NMR (200 MHz, CDCl3): δ = 8.37-7.93 (6 H, m), 7.7 (2 H, br s), 7.50-7.10 (6 H, m), 4.43-4.28 (2 H, m), 4.12 (2 H, q, J = 7.2), 1.23 (18 H, s), 0.92 (6 H, d, J = 7.0). 13C NMR (50 MHz, CDCl3): δ = 171.4, 134.5, 132.2, 131.5, 129.9, 128.5, 127.3, 125.7, 125.1, 122.1, 80.1, 50.6, 28.2, 18.1. HRMS (ESI): m/z calcd for [C36H42N4O6 + Na]+: 649.3002; found: 649.2997.
Selected analytical data for (R)-2a: Yield 35%, colorless solid as a foam. Mp 70-75 °C. [α]D 25 = -25.5 (c 0.9, CH2Cl2). 1H NMR (200 MHz, CDCl3): δ = 8.22-7.93 (6 H, m), 7.6 (2 H, br s), 7.51-7.08 (6 H, m), 4.97 (2 H, d, J = 8.8), 4.32-4.04 (2 H, m), 1.18 (18 H, s), 0.86 (6 H, d, J = 7.0). 13C NMR (50 MHz, CDCl3): δ = 171.4, 134.5, 132.2, 131.5, 129.9, 128.5, 127.3, 125.7, 125.1, 122.1, 80.1, 50.6, 28.2, 18.1. HRMS (ESI): m/z calcd for [C36H42N4O6 + Na]+: 649.3002; found: 649.2994.

5

General procedure for synthesis of compounds of type 3
To α,ω-diamine precursor dissolved in CH2Cl2, excess TFA was added (ca. 10 equiv), and the resulting mixture was stirred overnight at r.t. After that time, the solvent was removed and the pH of the residue was adjusted to <7 the by addition of 10% aq NaOH. This was extracted with CH2Cl2 and dried over MgSO4. Filtration of MgSO4 and removal of the solvent resulted in 3a-d in high yields.
Selected analytical data for (S)-3a: Yield 94%, colorless solid as a foam. Mp 166-168 °C. [α]D 25 -39 (c 0.9, CH2Cl2). 1H NMR (200 MHz, CDCl3): δ = 9.29 (2 H, br s), 8.65-7.91 (6 H, m), 7.47-7.13 (6 H, m), 5.30 (4 H, s), 3.29 (2 H, q, J = 7.0), 1.15 (6 H, d, J = 7.2). 13C NMR (50 MHz, CDCl3): δ = 174.2; 135.0, 132.6, 131.1, 129.6, 128.3, 126.9, 125.3, 125.1, 120.9, 120.4, 51.5, 21.2. HRMS (ESI): m/z calcd for [C26H27N4O2 + H]+: 427.2134; found: 427.2142.
Selected analytical data for (R)-3a: Yield 92%, colorless solid as a foam. Mp 172-175 °C. [α]D 25 +48.9 (c 0.9, CH2Cl2). 1H NMR (200 MHz, CDCl3): δ = 9.22 (2 H, br s), 8.44-7.93 (6 H, m), 7.49-7.15 (6 H, m), 3.34 (2 H, q, J = 7.0), 1.15 (6 H, d, J = 7.2). 13C NMR (50 MHz, CDCl3): δ = 175.1, 135.0, 132.9, 131.4, 129.6, 128.5, 127.0, 125.8, 125.4, 122.0, 121.2, 51.3, 21.3. HRMS (ESI): m/z calcd for [C26H27N4O2 + H]+: 427.2134; found: 427.2122.