Reaction Steps
To a solution of Compound 20b (12.1 mg, 4.37×10−2 mmol) and DMAP (57.5 mg, 0.44 mmol) in dry Ch2Cl2 (5 mL) cooled in an ice-water bath was added benzyloxyacetyl chloride (16.1 mg, 8.74×10−2 mmol) followed by stirring at room temperature for 4 hours. The reaction mixture was concentrated under reduced pressure and the residue was purified by flash column chromatography (silica gel, 20 percent EtOAc in hexane) to give 13.5 mg (73 percent) of Compound 38: pale yellow oil; Rf=0.52 (20 percent EtOAc in hexane); IR (neat) 2956, 2212, 1755, 1188, 1069 cm−1; 1H NMR (300 MHz, CDCl3) δ8.32 (d, J=7.44 Hz, 1H), 8.09-8.00 (m, 1H), 7.92-7.79 (m, 2H), 7.58-7.46 (m, 3H), 7.44-7.28 (m, 6H), 6.33 (t, J=1.35 Hz, 1H), 4.68 (s, 2H), 4.24 and 4.18 (AB q, J=16.59 Hz, 2H), 2.52-2.22 (m, 4H), 1.98-1.66 (m, 4H); 13C NMR (75 MHz, CDCl3) δ170.5, 134.2, 133.4, 132.6, 131.9, 129.8, 129.3, 129.2, 128.9, 128.7, 127.1, 127.0, 126.5, 125.9, 124.1, 123.4, 121.3, 103.4, 94.5, 80.8, 79.0, 74.1, 70.2, 68.0, 28.2, 28.1, 22.5, 21.4; MS (+CI) m/z (relative intensity) 435 (M+, 1), 271 (100).
