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The reaction of aryl(3-isocyanopyridin-4-yl)methanones 1, easily prepared from commercially available pyridin-3-amine, with aryl Grignard reagents gave, after aqueous workup, 2,3-diaryl-3H-pyrrolo[2,3-c]pyridin-3-ols 2. These rather unstable alcohols were O-acylated with Ac 2 O in pyridine in the presence of a catalytic amount of 4-(dimethylamino)pyridine (DMAP) to afford the corresponding 2,3-diaryl-3H-pyrrolo[2,3-c]pyridin-3-yl acetates 3 in relatively good yields.Introduction. -As part of our program to explore the potential of the reactions of ortho-functionalized phenyl isocyanides with organometals for heterocycle synthesis [1], we have recently demonstrated that 2-isocyanophenyl ketones can be converted into 2,3-disubstituted 3H-indol-3-ols in generally good yields on treatment with Grignard reagents [1e]. As an extension of this synthesis, we envisioned that a synthesis of 2,3-disubstituted 3H-pyrrolo[2,3-c]pyridin-3-ols could be accomplished by reacting 3-isocyanopyridin-4-yl ketones with Grignard reagents. Here, we report the results of such a study. The investigation has indicated that the reactions of aryl(3-isocyanopyridin-4-yl)methanones 1 with aryl Grignard reagents provide a convenient synthetic approach to 2,3-diaryl-3H-pyrrolo[2,3-c]pyridin-3-ol derivatives 3. Due to instability of these alcohols during purification procedures, they were isolated as O-acetylated derivatives. There have been so far no reports on the synthesis of this heterocyclic skeleton, 3H-pyrrolo[2,3-c]pyridin-3-ol.

A convenient method for the synthesis of 2,4,8-trisubstituted 1,7-naphthyridines 6 by the reaction of (E)-4-(1-aryl-2-methoxyethenyl)-3-isocyanopyridines 4, which could be easily prepared from commercially available 3-aminopyridine via aroylation of lithium (4-lithiopyridin-3-yl)pivalamide with Nmethoxy-N-methylbenzamides, with excess organolithiums has been developed.

A one-pot procedure for the preparation of 1-amino-1-aryl-1,2-dihydropyrrolo[3,4-c]pyridin-3-one derivatives from pyridine-3-carbonitrile and aromatic tertiary amides has been developed. Thus, the reaction of 4-lithiopyridine-3-carbonitrile, generated by the treatment of pyridine-3carbonitrile with lithium 2,2,6,6-tetramethylpiperidide (LTMP), with aromatic tertiary amides in THF at-78 ˚C yields the pyrrolopyridinone derivatives in moderate yields. In the course of our study on the development of new methods for the preparation of heterocyclic compounds, we became in need of 2-aroylpyridine-3-carbonitriles. So we attempted the reaction of 4-lithiopyridine-3-carbonitrile 1 with N-methoxy-N-methylbenzamide. However, we were surprised to find that this reaction resulted in the formation of 1-methoxy(methyl)amino-1-phenyl-1,2-dihydropyrrolo-[3,4-c]pyridin-3-one. Herein, we wish to report the results of our study on the reaction of lithiopyridinecarbonitriles with aromatic tertiary amides, which offer a simple synthetic method for 1-amino-1-aryl-1,2-dihydropyrrolo[3,4-c]pyridin-3-one derivatives. The 1,2-dihydropyrrolo[3,4-c]pyridine-3-one structure has been reported to be involved in the naturally occurring isoniazid-NAD(P) adducts. 2 1,2-Dihydropyrrolo[3,4-c]pyridine-3-one derivatives have been mainly prepared by the reduction of pyrrolo[3,4-c]pyridine-1,3-diones. 2,3 Recently, a method based on microwave-assisted intramolecular hetero-Diels-Alder cycloaddition of acetylenic pyrimidines has been reported. 4 However, there have been no reports on the synthesis of this heterocyclic derivatives carrying an amino group at the 1-position. First, the reaction of 4-lithiopyridine-3-carbonitrile with N-methoxy-N-methylbenzamide was examined under conditions illustrated in Scheme 1. Thus, the 4-position of pyridine-3-carbonitrile (1) was lithiated