Yield:-

Reaction Conditions:

with di-isopropyl azodicarboxylate;triphenylphosphine in tetrahydrofuran at 0 - 20; for 2 h;Mitsunobu reaction;

Steps:

9

Synthesis of azide 14dw; Synthesis of azide 14dw To a mixture of ethyl salicylate (1.0 g, 6.0 mmol), 2-bromoethanol (0.445 mL, 6.06 mmol), and triphenylphosphene (1.8 g, 6.9 mmol) in THF (10 mL) was added diisopropyl azodicarboxylate (DIAD, 1.40 mL, 6.60 mmol) at 0 C. The mixture was slowly warmed up to RT and stirred for 2 h. The reaction mixture was concentrated and redissolved in ethyl ether (50 mL). It was washed with brine (3 x 50 mL), dried (Na2S04), concentrated and purified by flash chromatography (silica gel, 5% ethyl acetate in hexane) to yield 0.8 g of the intermediate bromoethyl ether. The bromoethyl ether (0.678 g, 2.4 mmol) was dissolved in DMF (5 mL) and sodium azide (0.473 g, 7.2 mmol) was added. The mixture was heated in an oil bath at C for 2-3 h. The reaction mixture was diluted with ether (50 mL), washed with water (4 x 50 mL), dried (anhydrous Na2S04), and concentrated under reduced pressure. The crude product was purified by flash chromatography (silica gel, 10% ethyl acetate in hexane) to yield 0.52 g (89%) of pure azide 14dw.

References:

WO2005/85266,2005,A2 Location in patent:Page/Page column 244