Pyridines 3,4-fused

Bhandari A, Li B, Gallop MA, Solid-phase synthesis of pyrrolo[3,4-6]pyridines and related pyridine-fused heterocycles, Synthesis, 11 1951-1960, 1999. 

The synthesis of the triazolo-pyridine-fused 1,3-diazocine 20a was achieved starting from 56a, which by de-O-benzoylation followed by reaction with NaN3 in DMF afforded the triazolo-pyridine 57. The latter by treatment with a mixture of acetone and 2,2-dimethoxypropane in the presence of acid afforded the O-isopropylidene derivative 60. The Mitsunobu reaction led to the diazocine 19a, which, as mentioned in Section 14.05.2.5 (Scheme 2), afforded 20a in 19% overall yield (Scheme 11) <2005JME6454>. 

A series of planar chiral pyridine-fused ferrocene analogs (366) have been prepared and the enantiomers are resolved by chiral High performance (pressure) liquid chromatography (HPLC) see High Performance Liquid... 

Sml2-H20-amine mediated diastereoselective intramolecular couplings were reported for the synthesis of dihydrobenzofuran, and a radical mechanism was proposed to account for this reaction <03OBC2423>. A similar approach for the synthesis of pyridine-fused polycyclic amines was also developed by use of AlBN/BUjSnH as a reducing system <03TL2995>. 

A simple exercise on the synthesis of a pyridine fused to a pyrrole (or an indole with an extra nitrogen atom). 

Five-Membered Unsaturated Heterocycles 1151 Structures of Pyrrole, Furan, and Thiophene 1152 Electrophilic Substitution Reactions of Pyrrole, Furan, and Thiophene 1153 Pyridine, a Six-Membered Heterocycle Electrophilic Substitution of Pyridine Nucleophilic Substitution of Pyridine Fused-Ring Heterocycles 1158 Nucleic Acids and Nucleotides 1160 Structure of Nucleic Acids 1163 Base Pairing in DNA The Watson-Crick Model Nucleic Acids and Heredity 1166 Replication of DNA 1167... 

The addition of l-bromo-2-chlorocyclopropene to furopyridines occurred in high yield and provided access to a range of pyridine-fused benzocyclopropenes 232... 

H. Pyridines Fused to Five-Membered Heterocycles 1. Thienopyridines... 

Using a phosphazene base allows unreactive nitroaromatic compounds to condense with ethyl isocyanoacetate to give C-annelated pyrroles. Stable 2H-isoindoles with electron-withdrawing groups have been prepared using the reaction of dinitrobenzene derivatives with isocyanoacetate in the presence of a phosphazene base (BTPP). The structure of an isoindole was confirmed by X-ray crystallographic analysis, and this substance existed in the solid phase only as the 2H-isomer. The reaction of 6-nitroquinoline gave a pyridine fused isoindole [20] (Scheme 5.5). 

Bell. T.W. Guzzo. F. Stable potassium complex of a pyridine-fused hexaaza[18]annulene. A new rival for 18-crown-6. J. Am. Chem. Soc. 1984. 106. 6111-6112. 

This reaction has been extended to the synthesis of thiophene and pyridine fused pyrrole derivatives. 

Other Pyridine-fused Thiophen-containing Systems.—A number of thieno-quinolines such as (557) and (558) have been prepared by applying the... 

P-unsaturated aldehydes or ketones followed by treatment with t-BuSH and cyclization with HBr (Scheme 92) (13H885). Pyridine-fused 2,3-dihydro-4ff-thiopyran-4-ones are also prepared in a three-step sequence starting with the condensation of 2-chloropyridine with a,P-unsaturated aldehydes, followed by oxidation of the formed compound with Mn02 and cyclization with NaSH (13HCA624). Using 3-aryl-2-ary-limino-5-benzylidenethiazolidine-4-thiones as heterodienes, the inverse-electron-demand hDA reaction with norbornene as dienophile at room temperature affords complex hetero-fused thiopyrans (13T1337). 

The field of stable silylenes commenced with the synthesis of compound 59, isostruc-tural with carbene 58b, in 1994 . This development was promptly followed by reports of four additional examples 60 , the satnrated analog to 59 and the benzene- and pyridine- fused bicyclic silylenes 61, 62 and 63. 

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