6-Bromo-1,1,4,4,7-pentamethyl-1,2,3,4-tetrahydronaphthalene → 2-Pyridinecarboxamide

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Reaction Steps

2-Bromo-3,5,5,8,8-pentamethyl-5,6,7,8-tetrahydronaphthalene 33 (620 mg, 2.2 mmol) and the acetylpyridineamide 36a (500 mg, 2 mmol) were converted by a similar method as described above to obtain the intermediate 34 in over 80% yield. To a solution of the pyridine amide 34 (432 mg, 1 mmol) in 5 mL of THF at -78° C. was added 1.5M DIBAL toluene solution (0.7 mL, 1.05 mmol) and the resulting yellow clear solution was warmed up to -20° C. slowly in 60 min. and then was quenched with water. Removal of solvent and chromatography of the crude mixture afforded the pyridinealdehyde 35 in 83% yield as a white solid. 1H-NMR (CDCl3) δ1.25 (s,2(CH3)), 1.29 (s,2(CH3)), 1.70 (s,2(CH2)), 1.96 (s,CH3), 5.47 (s,=CH), 5.92 (s,=CH), 7.10 (s,ArCH), 7.11 (s,Ar-CH), 7.70 (d,J=8.0 Hz,Pyr-CH), 7.88 (d,J=8.0 Hz,Pyr-CH), 8.72 (s, Pyr-CH), 10.06 (s,CHO).

Provenance & Evidence