[Br:1][C:2]1[CH2:6][C:5]([C:12](OCC)=[O:13])([C:7](OCC)=[O:8])[CH2:4][C:3]=1[Br:17].[H-].C([Al+]CC(C)C)C(C)C.CC(C)=O.[OH-].[Na+]>C1COCC1.O>[Br:1][C:2]1[CH2:6][C:5]([CH2:7][OH:8])([CH2:12][OH:13])[CH2:4][C:3]=1[Br:17]
Under nitrogen, a stirred solution of 8.7 g (23.5 mmol) of 1,2-dibromo-4,4-di(carboethoxy)cyclopentene (Step 4) in 70 mL of anhydrous THF at -78° C. was treated with 80 mL of diisobutylaluminum hydride (1.5 M in toluene) over a 20 minute period. The reaction was allowed to warm to ambient temperature overnight and was slowly treated with 20 mL of acetone followed by 10 mL of 2.5 N sodium hydroxide. Water (100 mL) was added and the solution extracted 5 times with ethyl acetate. The combined extracts were washed with brine, dried (Na2SO4), and concentrated in vacuo to give 5.7 g (85%) of 1,2-dibromo- 4,4-di (hydroxymethyl)cyclopentene (10 in Synthetic Scheme III) as a colorless oil: NMR (CDCl1) δ2.20 (s, 2H), 2.50 (s, 4H), 3.70 (s, 4H).
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