Diethyl Carbonate → 9-Iodo-3,4,7,8-tetrahydro-[1,4]diazepino[7,1-a]isoquinoline-2,5-dione

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Reaction Conditions

Reaction Steps

(Z)-ethyl 2-(5-iodo-3,4-dihydroisoquinolin-1(2H)-ylidene)acetate. To a yellow cooled solution of 5-iodo-1-methyl-3,4-dihydroisoquinoline (30.1 g, 111 mmol) in dry THF (900 mL) was added dropwise a solution of LDA (2M in THF, 111 mL, 222 mmol) at −78° C. The resulting brown solution was stirred for at −78° C. for 45 min and a solution of diethyl carbonate (14 mL, 116 mmol) in THF (80 mL) was then added dropwise. The mixture was stirred at −78° C. for another 45 min, and then poured onto brine. The resulting yellow suspension was filtered and the filter cake was washed with AcOEt. The filtrate was extracted with AcOEt, and the combined org. phases were dried over Na2SO4, filtered and concentrated in vacuo to give the title compound (40.0 g) as a brown oil that was used as it is in the next step. UPLC-MS: MS 344.1 (M+H+); UPLC rt 1.28 min.

Provenance & Evidence