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6th November 2011 @ 22:27
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Synthesis of ether-linked analogues of TCMDC-123812 and TCMDC-123794 by conversion of alcohol PMY 18-1 to its alkyl bromide using phosphorous tribromide and subsequent displacement.

Reaction Scheme

Reaction Start Time: 1105 07/11/11
Phosphorous tribromide (50 μL, 0.52 mmol, 0.4 equiv.) was dissolved in Et2O (2.5 mL) and cooled in ice/brine. Pyridine (0.03 mL, 0.4 mmol, 0.3 equiv.) was added. White precipitate forms. PMY 18-1 (287 mg, 1.31 mmol, 1 equiv.) in Et2O (5 mL) was added dropwise over 5 mins. After 10 minutes. Reaction is a slurry, white to orange to red precipitate. After 30 minutes, diluted with Et2 (5 mL) and sat. NaHCO3 (4 ml) added. Reaction purple. Washed with water (3 × 10 mL) and brine, then dried (MgSO4).

Reaction abandoned, NMR shows multiple products

TLC (25% EtOAc/hexane) visualised with UV and vanillin:
TLC


NMR:
1H NMR intermediate, poor shim


References:
doi: 10.1021/ol8018105
doi: Organic Syntheses, Vol. 23, p. 88 (1943); Coll. Vol. 3, p.793 (1955).

Risk and Hazard Assessment:
Risk Assessment
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Reaction Scheme
Risk Assessment
TLC
1H NMR intermediate, poor shim