Ferrocenes Containing a Heterocyclic Ring Fused to the Ferrocene

Ferrocenes Containing a Heterocyclic Ring Fused to the Ferrocene 

The first reported ferroceno heterocyclic compound of the type 1 was A-methyltetrahydropyridoferrocene (4). This compound was obtained from an anomalous Leuckart-Eschweiler-Clark reaction of 2-aminomethylferrocene (5 R = H), formaldehyde, and formic acid,4 although the structure 4 was not immediately recognized for this compound.5-8 The heterocyclic compound 4 can be used as an entry to 1,2-disubstituted ferrocenes since on reaction with potassium amide in liquid ammonia7 or with potassium hydroxide in methanol9 its 

Bischler -Napieralski ring closure of 5 (R = CHO) with phosphorus oxychloride6,8 9 and of 5 (R = COCH3) with phosphorus oxychloride6, 8 or polyphosphate ester10 gave 8 (R = H and R = CH3, respectively). Reduction of 8 (R = H) with lithium aluminum hydride 

2-disubstituted ferrocene (13) on treatment with hydrochloric acid gives 14 which can be oxidized with manganese dioxide to give 15.9 

The Sohmidt reaction of l,2-(a-ketotetramethylene)ferrocene (16) with hydrazoic acid and sulfuric acid in benzene9 or the Beckmann 

Treatment of the oxime (17) with lithium aluminum hydride-aluminum chloride led to a rearrangement of the ferrocene residue to give 20.11 oxime (21) was unchanged under these conditions. Treatment of the quaternary methiodide of 20 with base led to the ring-opened product (22). 

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II. Ferrocenes Containing a Heterocyclic Ring Fused to the Ferrocene. 2... 

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