A Short Synthetic Route to 4,7‐Dihalogenated 1,10‐Phenanthrolines with Additional Groups in 3,8‐Position: Soluble Precursors for Macrocyclic Oligophenanthrolines

Abstract

A short and efficient preparation of 3,8‐dialkylated or 3,8‐diarylated 1,10‐phenanthrolines‐4,7‐diones is described. Their chlorination or bromination furnishes the corresponding, highly soluble 4,7‐dichloro‐ or 4,7‐dibromo phenanthrolines that constitute versatile precursors to macrocyclic oligophenanthrolines with exo‐coordination sites. They can be further reacted by nucleophilic aromatic substitution or Heck‐coupling reactions.

The Proton Sponge Effect: Substitution of Quino[7,8‐h]quinoline and the First Structurally Characterised Derivatives

“…[5] Our modification gave us a reliable and large-scale route to 6. [13] The very properties that make 6 intriguing also hamper its usability; purification by standard techniques is highly problematic, and so reactions were optimised to produce high-yielding reactions with simple workup procedures. Initially, we were interested in elaborating the rings by nucleophilic aromatic substitution, as this would give us a route to selectively functionalise the rings.…”

“…1 13 -3 , F(000) = 1016, T = 100(2) K. A total of 10378 reflections were collected by using a Rigaku MM007 rotating anode in the range 6.58 Ͻ 2θ Ͻ 144.00°. The residue was extracted with CH 2 Cl 2 (200 mL), and the organic layer was washed with water (2 ϫ 200 mL), filtered and dried with MgSO 4 .…”

“…Initially, we were interested in elaborating the rings by nucleophilic aromatic substitution, as this would give us a route to selectively functionalise the rings. [13] The very properties that make 6 intriguing also hamper its usability; purification by standard techniques is highly problematic, and so reactions were optimised to produce high-yielding reactions with simple workup procedures. We first investigated the substitution of the 4,9chlorides on 6 with oxygen-donor nucleophiles (Scheme 3).…”

“…A solution of p-toluidine (2.75 g, 25.6 mmol) and 6 (0.100 g, 0.334 mmol) was stirred at 150°C for 4 h. The reaction mixture was diluted with CH 2 Cl 2 (200 mL) and washed with water (200 mL) and 6 m KOH (20 mL 13 To a mixture of fuming nitric acid (1 mL) and concentrated sulfuric acid (1 mL) heated briefly to initiate NO 2 generation was added 6 (0.050 g), and the reaction mixture was stirred for 2 min at 120°C. The mixture was poured onto ice.…”

“…H NMR (500 MHz, CDCl 3 ): δ = 1.42 [s, 9 H, 6973 C(CH 3 )3 ], 6.84 (d, 3 J 10,11 = 6.2 Hz, 1 H, 11-H), 6.87 (d,3 J 2,3 = 5.4 Hz, 1 H, 3-H), 7.21 (d,3 J 2,3 = 8.6 Hz, 2 H, 2-PhH), 7.56 (d, 3 J 2,3 = 8.6 Hz, 2 H, 3-PhH), 7.78 (d, 3 J 5,6 = 8.7 Hz, 1 H, 6-H), 7.93 (d, 3 J 10,11 = 6.2 Hz, 1 H, 10-H), 8.09 (d, 3 J 7,8 = 6.2 Hz, 1 H, 7-H), 8.50 (d, 3 J 7,8 = 6.2 Hz, 1 H, 8-H), 8.62 (d, 3 J 5,6 = 8.7 Hz, 1 H, 5-H), 8.80 (d, 3 J 2,3 = 5.4 Hz, 1 H, 2-H); 16.30 (s, 1 H, NH) ppm 13. C NMR (125 MHz, CDCl 3 ): δ = 31.5 (t), 34.6 (q), 105.4 (s), 111.1 (s), 115.0 (q), 116.7 (q), 119.5 (q), 120.6 (s), 122 (s), 124.1 (s), 125.6 (s), 126.1 (q), 127.4 (s), 127.7 (s), 137.0 (q), 138.4 (s), 140.4 (q), 148.5 (q), 148.7 (s), 149.3 (q), 151.4 (s), 162.8 (s) ppm.…”