Benzoyl chloride → 1-Benzoyl-1,2,3,4-tetrahydrobenzo[c]-1,5-naphthyridine

Participants

Reaction Steps

A stirred solution of 1,2,3,4-tetrahydrobenzo[c]-1,5-naphthyridine (4.6 g) and KOH-dried pyridine (50 ml) was treated dropwise over one minute with benzoyl chloride (8.4 g). A crystalline precipitate formed. The stirred suspension was heated (steam bath) for 1.25 hours and the resultant solution was then stirred overnight at ambient temperature during which a crystalline precipitate formed. The mixture was decanted into water (200 ml), basified with 10% sodium hydroxide solution and extracted with dichloromethane. The dried (Na2SO4) organic phase was filtered and evaporated to dryness (7.47 g of crystalline solid). Recrystallization from toluene afforded 6.25 g of crystals, m.p. 208.5°-210.5° C. An aliquot of the material (4.81 g) was further purified by preparative HPLC (silica gel, eluted with ethyl acetate). The appropriate fractions were concentrated and the residue was recrystallized from toluene (100 ml) to give 4.14 g of crystals, m.p. 208°-210° C.

Provenance & Evidence