[Intramolecular alkylaton of aromatic compounds. 34. Synthesis of pyridinylmethylindolines as potential precursors of ergolines] . / Intramolekulare Aromatenalkylierungen. 34. Mitt.: Synthese von Pyridinylmethylindolinen als potenzielle Edukte für Ergoline.

The carbinoles 3 prepared from the N-protected indolaldehydes 2 and bromomethoxypyridine 1 can smoothly be hydrogenolized to the lutidinylindoles 4 which in turn give the corresponding indolines 5 by NaCNBH3-reduction. Treatment of 3a by acid the trihetarylmethane 9 and 5-methoxypyridine-2-carboxaldehyde 10 are generated. The acetylpyridine 7 is found as a by-product of 3c. As by-product of the reduction the borane adduct 8 is detected.

[Intramolecular alkylation of aromatic compounds. 35. Di- and tetrahydropyridinemethylindolines as potential precursors of ergolines] . / Intramolekulare Aromatenalkylierungen. 35. Mitt.: Di- und Tetrahydropyridinylmethylindoline als potenzielle Vorstufen zu Ergolinen.

In the presence of methyl chloroformate, compound 6a is reduced by NaCNBH3 yielding the 1,6-dihydropyridine derivative 7. Under the same conditions the indoline 10 accessible from 6a via 9a gives a mixture of the 1,4- and 1,6-dihydropyridine derivatives 11 and 12. As by-product of the reduction the borane adduct 13 is detected. In contrast the methoiodide 1 is reduced by NaBH4 or DIBAH giving a separable mixture of the diastereomers of the tetrahydropyridines 2 and 3; on catalytic hydrogenation the piperidine derivative 4 is formed. Cleavage of the enolether moiety in 3a and 7 provides the corresponding piperidones 5 and 14, respectively. Using prolonged reaction time 7 is hydrolized quantitatively furnishing the 1,4-diketone 15.