Stannous chloride dihydrate → 4-(8-benzyloxy-7-methoxy-3H-pyrazolo[3,4-c]quinolin-1-yl)benzonitrile

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Reaction Steps

A solution of sodium nitrite (483 mg, 6.99 mmol) in water (2.5 ml) is added dropwise over the course of 1.5 h at (−)1-0° C. to a suspension of 4-(3-amino-6-benzyloxy-7-methoxy-quinoline-4-carbonyl)benzonitrile (2.60 g, 6.35 mmol) in concentrated hydrochloric acid (50 ml). The mixture is subsequently stirred for a further 30 min. A solution of tin(II) chloride dihydrate (5.02 g, 22.23 mmol) in concentrated hydrochloric acid (3.8 ml) is then added at (−)5° C. The suspension obtained is stirred at room temperature for 1 h, subsequently diluted with water (500 ml), stirred for 30 min and filtered with suction. The filter cake is rinsed with water and dried in a high vacuum, giving 4-(8-benzyloxy-7-methoxy-3H-pyrazolo[3,4-c]quinolin-1-yl)benzonitrile (2.42 g, 5.95 mmol) as a solid having a melting point of 222.8° C. (decomposition). MS: 407.1 (M+H+), TLC (HPTLC): Rf=0.27 (ethyl acetate).

Provenance & Evidence