Phosphorus oxide (P4O10) → 1-Chloromethyl-6-methoxy-3,4-dihydro-isoquinolinium chloride

Participants

Reaction Steps

Two equiv. of P2O5 (12.9 g) was boiled in xylenes (180 mL) as a 0.25 M solution. The crude product from Step 1 above was also first boiled in xylenes (45 mL) to make a 0.5 M solution, and it was then added dropwise via an addition funnel to the P2O5 solution. The mixture was stirred and heated at reflux for 1 h. The reaction was then cooled to RT and the xylenes decanted off at this point. The flask was then placed in an ice bath and stirred while ice, water, EtOAc, and finally 4 M NaOH were added carefully until the pH>12. Reaction was kept <25° C. until pH=12 was reached. The reaction was then extracted with EtOAc (3×). The combined organic extracts were dried over MgSO4 and concentrated to give a dark solution. This was cooled in an ice bath while 400 mL of cold Et2O was added followed by 100 mL of cold HC1/Et2O. A precipitate formed and was filtered away, washing with Et2O. The solid was immediately placed on high vac for 2 h to give the target product as a colored foamy solid. This crude product was directly used in the next step without further purification.

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