Phthalic Anhydride → 5-Bromopentylphthalimide

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Phthalic anhydride (43.0 g, 0.29 mole) and 5-aminopentanol (29.9 g, 0.29 mole) in 250 ml dry toluene (dried over 4A sieves) were heated to reflux in a 120° C. oil bath with stirring for three hours. The system was equipped with a Dean-Stark trap for the azeotropic removal of water (5.3 ml). Upon TLC confirmation of complete formation of the intermediate, 5-hydroxypentylphthalimide (Rf =0.66 (A)), phosphorous tribromide (18.2 ml, 0.19 mole) in 20 ml dry toluene was added dropwise to the hot reaction mixture and the mixture was stirred for 1.5 hours at 100° C. After removal of an orange precipitate by filtration through a pad of Celite, the filtrate was concentrated by rotary evaporation, and the resulting oil was crystallized from absolute ethanol as white plates. Yield: 64.7 g (75.3%). Mp 59.5°-66.0° C. TLC: Rf =0.78 (A). MW calc. 295.10, found 295. Anal. calc. for C13H14NO2Br: C, 52.72; H, 4.76; N, 4.73; Br, 26.98. Found: C, 53.17; H, 4.91; N, 4.62; Br, 27.14. HPLC 100%. 1H NMR (CDCl3) 1.50 (2H, m), 1.72 (2H, m), 1.92 (2H, m), 3.40 (2H, t, 7 Hz), 3.70 (2H, t, 7 Hz), 7.72 (2H, m) and 7.90 (2H, m) for AA'BB"system.

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