2.6- diformyl phenols

Thoer, A., Denis, G., Delmas, M., Gaset, A. The Reimer-Tiemann reaction in slightly hydrated solid-liquid medium a new method for the synthesis of formyl and diformyl phenols. Synth. Common. 1988,18, 2095-2101. 

Macrocyclic Schiff base compartmental ligands (750) (Robson-type ligands) derived from the [2 + 2] condensation of a 2,6-diformyl- or 2,6-diketo-substituted phenol and a diamine are very prominent in dinuclear Ni coordination chemistry.1901-1903 Particular interest lies in magnetic exchange interactions between the adjacent metal ions as well as in bioinorganic chemistry, where such dinuclear complexes have been proposed as synthetic analogues for bimetallosites. 

B. H-(2,4-Diformyl-S-hydroxyphenyl)acet amide. A suspension of 95 g of the phenol (prepared under Section A) (Note 6) in 1 L of aqueous 10% hydrochloric acid is stirred for 2 hr at room temperature. The colorless solid (Note 7) is filtered by suction and twice suspended in water at 40°C. Final filtration is followed with a water wash (1 L, 40°C), and the solid is sucked down on the filter. Crystallization from 800 mL of acetonitrile affords 21.8-22.3 g (66-67.5%) of TV-(2,4-diformyl-5-hydroxyphenyl)acetamide, mp 215-217°C (Note 8). 

Many macrocyclic SBs have been prepared by condensation of different dicarbonyl precursors (head units (55), see Scheme 16) such as 2,6-diformylpyridine (56, R = H, 56a), 2,6-diacetylpyridine (56, R = CH3, 56b), 2,6-diformyl-4-Z-phenol (57, Z = C1- 57a, CH3-, 57b), 2,6-diacetyl-4-Z-phenol (57, Z = C1—, 57c, Z = CH3, 57d) thiophene-2,5-dicarbaldehyde (58), furan-2,5-dicarbalde-hyde (59), pyrrole-2,5-dicarbaldehyde (60), 2,6-diformyl-4Z-thiophenol (61, Z = CH3, 61a Z Bu1, 61b) or /3-triketones (62) with a wide range of different diamines (lateral chains). The majority of SB macrocycles are symmetrical and contain either phenol or pyridine as head units. Asymmetrical SB macrocycles have also been prepared. The SB macrocycles are designated [1 + 1] and [2 + 2] depending on the number of head and lateral units present (see Scheme 17). With certain precursors (i.e., 2,6-diacetylpyridine and l,3-diamino-2-hydroxypropane) [3 + 3] and [4 + 4] macrocyclic complexes have also been synthesized.177-179 The [2 + 3] condensation products have also... 

Much research have been focused on compartmental SB macrocycles derived from 2,6-diformyl (diacetyl)phenols as head units (see Scheme 19). The coordination chemistry of the phenol-based compartmental ligands was reviewed.2 A series of symmetrical and less extensively asymmetrical macrocycles (having dissimilar lateral chains) have been prepared (Scheme 19). The variation of the lateral chains of the macrocycle gives ligands with different cavity size and flexibility. Thus, the N202 cavity of the ethylenediamine derivative (65a) can accommodate only the small Cu11 and Ni11 ions because it has little flexibility. The replacement of the dimethylene by a trimethylene... 

The ground and excited state proton transfer processes of 4-methyl-2,6-diacetyl-phenol and the influence of polar solvents on the outcome of the photochemical transformation of 2,6-diformyl-4-methylphenol (10) has been evaluated" " . The results obtained from the study of 10 indicate that the CO- -HO hydrogen bond is stronger in... 

In an attempt to establish the position of the two phenolic groups in micranthine, Bick and Todd ethylated iV-methylmicranthine dimethiodide and then subjected the resulting i r-methyl-0,0-diethylmicranthine dimethiodide to the Hofmann degradation. The i l-methyl-0,0-diethyl-micranthine methine so obtained was ozonized, and the neutral product from the ozonolysis was identified as 4, 5-diformyl-2-ethoxydiphenyl ether by direct comparison with an authentic sample. Thus, one of the phenolic... 

Like diamino alcohols, diaminophenols (aromatic analogues of l,5-diamino-3-hydroxypentane) turned out to be extremely useful counterparts in template condensation with 2,6-diformy]-4-substituted phenols. Tetranuclear nickel and zinc complexes of the macrocyclic Schiff base H4LI73O formed by 2 -I- 2 condensation of 2,6-diformyl-4-methylphenol and 2,6-bis(aminomethyl)-4-methylphenol in methanol, have been prepared (Eq. 8.37) [99]. 

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