1,1,3,3-Tetramethylguanidine → (3E)-3-[[3,5-dimethyl-4-(phenylmethoxy)phenyl]methylene]-1,4-dioxaspiro[4.5]decan-2-one

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Reaction Conditions

Reaction Steps

4.2 g lithium chloride (0.1 Mol), 20.0 g (83.2 mmol) of 4-benzyloxy-3,5-dimethylbenzaldehyde (D) and 31.62 g (108.2 mmol) of diethyl (3-oxo-1,4-dioxaspiro[4.5]dec-2-yl)-phosphonate (C) are suspended in 130 mL tetrahydrofuran and cooled to −20° C. At this temperature 12.5 mL (0.1 Mol) tetramethylguanidine are added dropwise. After the addition has ended the suspension formed is heated to ambient temperature and stirred for 1 hour. After the addition of 190 mL tert.butyl-methylether the organic phase is washed with 150 mL water and 30 mL saturated saline solution, dried and evaporated down. The resulting yellow oil is taken up in 145 mL methanol and stirred intensively for 1 hour at −10° C., during which time a white solid is formed. The solid formed is suction filtered, washed twice with 20 mL methanol/water (1:1) and dried at 45° C. Yield: 26.0 g (86% of theory)

Provenance & Evidence