Triphenylphosphine → 1,2-dihydro-1-carboethoxy-2-[trans-3-(3-pyridyl)allyl]-3H-indazol-3-one

Beteiligte Stoffe

Reaktionsschritte

A solution of diethyl azodicarboxylate (1.6 g) in chloroform (5 ml) was added dropwise to a mixture of 1,2-dihydro-1-carboethoxy-3H-indazol-3-one (1.5 g), triphenylphosphine (2 g) and trans-3-(3-pyridyl)-allyl alcohol [0.95 g; itself prepared from methyl trans-3-(3-pyridyl)-acrylate (J. Het. Chem., 1985, 22, 65) as an oil of satisfactory purity on reduction at 0° C. with a solution of di-isobutylaluminium hydride in toluene] in chloroform (20 ml). The mixture was stirred at ambient temperature for 16 hours and then evaporated to dryness. Diethyl ether was added, the mixture was filtered and the filtrate was evaporated The residue was chromatographed using an increasing gradient of ethyl acetate in petrol as eluant to give 1,2-dihydro-1-carboethoxy-2-[trans-3-(3-pyridyl)allyl]-3H-indazol-3-one (Ex. 213) as an oil (0.84 g) in 37% yield and of satisfactory purity as judged by NMR and mass spectral analysis.

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