Dinitrodiphenic acid

The present method is adapted from that of Loven. The resolution has been carried out with d-a-bromocamphor-TT-sulfonic acid (f-form) 2.3 with /-and d/-malic acids (d- and /-forms) with /-quinic acid and d-tartaric acid (d- and /-forms) and with d- and /-6,6 -dinitrodiphenic acids (d- and /-forms). Methods employing d-benzyimethylacetyl chloride, d-oxymeth-ylenecamphor, /-quinic acid, and d-camphoric anhydride are of theoretical interest only. The d/-amine is not resolved by the active camphor-lo-sulfonic acids or mandelic acids. ... 

Azaferrocene (206) has been prepared by the reaction of sodium pyrrole, cyclopentadienylsodium, and ferrous chloride,157 or better by the reaction of potassium pyrrole with cyclopentadienyliron dicarbonyl iodide.158 It has been found159 that dioxane is a better solvent than benzene for this latter reaction. This reaction has also been applied to 2,4- and 2,5-dimethylpyrrole,158 3-acetyl-2-methyl-and 3-acetyl-2,4-dimethylpyrrole,160 and 2-methylpyrrole.159 The 2-methylazaferrocene from this latter pyrrole has been resolved with (—)6,6 -dinitrodiphenic acid.159 A compound (207) believed to be an intermediate in the formation of azaferrocenes has been isolated.161... 

Carbodiimides have chiral structures similar to allenes, i.e., they can exist in optically active forms. Schloegl and Mechtler were the first to report a partial optical separation of N,N"-diferrocenylcarbodiimide into enantiomers by chromatography on acetylated cellulose, but other authors doubt the validity of these results. According to theoretical calculations a separation of carbodiimide enantiomers is not possible. N,N -diferrocenylcarbodiimide was also obtained in optically active form by kinetic resolution in the reaction with (-)-S-6,6"-dinitrodiphenic acid. Cervinka and coworkers isolated both enantiomers of (R,S)-N,N"-bis(o -phenylethyl)carbodiimide, and they found that they undergo racemization at room temperature. A recent study on the racemization mechanism of macrocyclic carbodiimides indicates that the open chain as well as the large ring carbodiimides racemize by nitrogen inversion or tra 5-rotation, while medium size cyclic carbodiimides racemize by cw-rotation. ... 

Pinidine (91) is an alkaloid of established structure from Finns jeffreyi. It has been synthesised from 2,6-lutidine in three simple steps (Scheme 4), followed by a separation of the isomers and a resolution of the appropriate racemate using (-)-6,6 -dinitrodiphenic acid (E. Leete and R.A. Carver, J.org.Chem., 1975, 40, 2151). 

The kinetic resolution should be considerably enhanced if a chiral dicar-boxylic acid capable of ring formation to both 6-hydroxy groups of skyrin would be applied. We selected for this purpose 6,6 -dinitrodiphenic acid dichloride (32) which can easily be obtained in both enantiomeric forms. Reaction of (+)-(R)-binaphthol 31 with racemic 32 afforded the (+)-lactone 33, [a]p +213°, whereas the unreacted acid 34 showed a negative rotation (Scheme 7). Further investigations with the optically pure reagents indicated that (+)-(R)-31 forms only a lactone 33 with (+)-(R)-32 whereas (-)-( )-31 reacts only with (-)-( )-32. The same results were obtained with tetrachlorodiphenic acid dichloride. Similar observations have recently been published by Miyano and co-workers (ref. 20) for 1,1 -binaphthyl-2,2 -dicarboxylic dichloride. 

Scheme 7. Reaction of rac. 6,6 -dinitrodiphenic acid dichloride (32) with (+)-(R)-binaphthol 31...

Scheme 8. Reaction of 6,6 -dinitrodiphenic acid dichloride with (+)-skyrin and (-)-flavomannin A...

Miyano s approach was effective also in the synthesis of ( )-6,6 -dinitrodiphenic acid (556) from 3-nitro-2-halobenzoic acids 557 or 558, via diesters 559 and 560, derived from (Ti)-binaphthol (4), in moderate yield and good optical purity, 80-85% d.e. [14],... 

The structure of conhydrine, i.e., l-(a-piperidyl)-propan-l-ol, has been deduced from a study of the Hofmann degradation of the base (33). It has now been fully confirmed by synthesis of the optically active base. a-Pyridylethyl ketone in hydrochloric acid solution is hydrogenated catalyticaUy in the presence of platinum and gives rise to a product which, after distillation in vaevx), consists of a mixture of both racemates of a-piperidylethylcarbinol, m.p. 87-90°. Fractional crystallization in ether yields the high-melting racemate, m.p. 100°. The two optically active enantiomorphs of this racemate are obtained by resolution with d- and Z-dinitrodiphenic acid. The dextrorotatory form, m.p. 121°, [oJ -flO.O in absolute ethanol, is identical with conhydrine (34). 

CrOj - 4,4 Dinitrodiphenic acid, 257 8, Monoxime, 246-8, o-Phenylenediamine - qumoxaline deriv, 356, Fluorene adduct, 270, red-yel... 

Dinitrodiphenic Acid (4 i -Dinitro-diphenyl-2 2 -dicarboxylic acid)... 

Kuhn and Albrecht (67) noted that, when 4,4 -dinitrodiphenic acid is converted to its quinine (Q) salt, the latter is unexpectedly and strongly dextrorotatory they attributed this to the adoption by the biphenyl skeleton of a dissymmetric configuration induced by the optically active alkaloid, and persisting for only so long as the salt exists. This can only be inferred and not proved directly, for only an inactive acid can be liberated from the salt on acidification ... 

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