The Selective Reduction of Aldehydes Using Polyethylene Glycol-Sodium Borohydride Derivatives as Phase Transfer Reagents

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• [Compd. No.: ir (paraffin oil), cm-1; 1H nmr (solvent), δ ppm] Compd. 1: ir, 3300, 2800, 2250, 1620, 1050; nmr (D2O) 8.1–7.5 (m, Ar-H), 3.7 (strong s, PEG chain), 3.4 (s, CH2O-BH-), 1.7, 0.45, -0.9, -2.2(4 singlets, B-H). Compd. 2: bp (°C), 106–108; ir, 3500, 1050; nmr, 3.2 (t, CH2-O), 2.1 (broad s, OH), 1.5 (heptet, C-H), 1.0 (d, CH3-). Compd. 3: bp (°C), 153–156; ir, 3500, 1050; nmr, 3.6 (broad triplet, CH2-O), 2.0–1.0 (mutiple signals), 1.0 (triplet, CH3-). Compd. 4: bp (°C), 171–174; ir, 3500, 1050; nmr, 3.5 (broad triplet, CH2-O), 2.0–1.0 (mutiple signals), 1.0 (triplet, CH3-). Compd. 5: bp (°C), 203–205; ir, 3500, 3100, 1500, 1450, 1050; nmr, 7.3 (s, Ar-H), 4.6 (s, CH2-O), 2.1 (s, -OH).
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