Ammonium Hydroxide → 5-(imino-morpholin-4-yl-methyl)-3,4-dihydro-1H-isoquinoline-2-carboxylic acid tert-butyl ester

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Reaction Steps

A solution of 5-bromo-3,4-dihydro-1H-isoquinoline-2-carboxylic acid tert-butyl ester 26a (0.4 g, 1.28 mmol) in tetrahydrofuran (10 mL) under argon, was cooled to −78° C. A solution of 2.5 M n-butyllithium in hexanes (0.61 mL, 1.53 mmol) was added dropwise over 5 min. After the addition, stirring was continued for 15 min at −78° C. 4-Morpholinecarbonitrile (0.172 g, 1.53 mmol) was added all at once and reaction continued for 90 min at that temperature. A saturated ammonium chloride solution was added at −78° C. After warming to room temperature the mixture was made basic (pH 9) with concentrated ammonium hydroxide and the product was extracted with dichloromethane. The combined organics were dried with magnesium sulfate, the solvent was evaporated and the residue purified by flash chromatography eluting with 6% methanol in dichloromethane containing 0.6% of ammonium hydroxide, to yield 0.24 g of 5-(imino-morpholin-4-yl-methyl)-3,4-dihydro-1H-isoquinoline-2-carboxylic acid tert-butyl ester 27a.

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