4,5‐Bis(dimethylamino)phenanthrene and 4,5‐Bis(dimethylamino)‐9,10‐dihydrophenanthrene: Syntheses and “Proton Sponge” Properties

Abstract

Strong, almost linear N ċ H ċ N hydrogen bonds are present in 1‐perchlorate and its 9,10‐dihydro derivative. The N ċ N distance is even shorter and the H/CH3 bridge coupling stronger than in the analogue with a fluorene skeleton. Unprotonated 1 could be generated via a dichlorinated seven‐membered dibenzosulfone.

Guanidines as Reagents in Proton-Coupled Electron-Transfer Reactions and Redox Catalysts

“…The structural analysis showed a distortion of the naphthalene ring plane, pointing to a compromise between aromatic stabilization and conjugation with the amino group. 105 Later, compounds such as 4,5-bis(dialkylamino)-fluorene 106 (pK a = 12.8), and 4,5-bis(dialkylamino)-phenanthrene 107 (pK a = 11.5) were synthesized and also shown to be strong Brønsted bases and proton sponges. In these compounds, the orientation of the amino groups towards each other (Figure 8) increases the steric strain.…”

Proton sponge phosphines: electrospray-active ligands

“…13 C{ 1 H} NMR (126 MHz, CDCl 3 ) d C (4): 153.4 (d, 1 J C-P 23.6, C 1 ), 152.5 (d, 4 J C-P 1.6, C 8 ), 141.8 (d, 1 J C-P 17.9, C 11 ), 138.2 (C 10 ), 137.2 (d, 2 J C-P 10, C 2 ), 134.3 (d, J C-P 21.6, C 12 ), 131.3 (s, C 3 ), 128.3 (d, J C-P 5.9, C 13 ), 127.9 (s, C 14 ), 126.4 (d, 5 J C-P 3.0, C 9 ), 125.9 (C 6 ), 124.7 (C 4 ), 124.0 (C 5 ), 115.8 (C 7 ), 46.6, 47.1 (N(CH 3 ) 2 on C 8 ), 44.6 (d, 4 J C-P 8, N(CH 3 ) 2 on C 1 ). 31 First pK aH of 3: 1 H NMR transprotonation experiments 19 . Compounds 1, 1•HBF 4 , 3 and 3•HBF 4 were prepared as described in the previous section.…”

Naphthalene 'proton sponges'

“…In the majority of salts, the naphthalene ring is virtually flat and both N atoms lie in the same plane. For some salts (X 7 = C 6 Cl 5 O 7 , BF 7 4 , SCN 7 ), the twisting (by no more than 4 ± 5 8) of the planes of C(1)7C( 9)7C(10)7C(4) and C(8)7C( 9)7C(10)7C(5) around the central bond C(9)7C (10) still takes place. As a result, the molecule acquires a propeller shape, and the nitrogen atoms diverge in different directions from the mean plane (up to 0.25 # A).…”

“…This conclusion is confirmed by analysis of 13 C NMR spectra (Table 13). Since in benzene derivatives the shielding effects of NMe 2 and MeO groups are opposite and correspond to the Hammett s-constants, it is reasonable to conclude that the decreased electron donor capacity of the NMe 2 groups in 1dimethylamino-and 1,8-bis-(dimethylamino)naphthalenes is a a The 1 H NMR spectra of `proton sponge' salts with the following anions: I 7 , NCS 7 , PF 7 6 Y Ph4B 7 were also recorded in CD3CN. 94 The values of chemical shifts in these salts are very close to those cited above.…”