Benzaldehyde → (2-phenyl-4H-[1,3]dioxino[5,4-b]pyridin-6-yl)methanol

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Reaction Steps

To a stirred suspension of 31 g. (0.2 mole) of 2,6-bis-(hydroxymethyl)-3-hydroxypyridine (U.S. Pat. No. 3,700,681) in 101 ml. (1 mole) of benzaldehyde at 20°-25° C. is added dropwise over 45 min. 56.7 g. (0.4 mole) of borontrifluoride etherate. The mixture is allowed to stir at room temperature for 2 hrs., and the excess benzaldehyde removed under reduced pressure. The residue, after standing at room temperature, is added to 75 ml. of a 10M aqueous sodium hydroxide solution, and the product extracted into methylene dichloride. The organic phase is separated, concentrated in vacuo to 100 ml. and the methylene dichloride diluted with n-hexane. The crude product which crystallizes is filtered and dried, 37.4 g. (77% yield), m.p. 85°-89° C. Further purification is effected by recrystallization from acetone-n-hexane, 22.1 g., m.p. 114°-118° C.

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