Magnesium chlorochromate

To a stirred suspension of 32.3 g (0.1 mol) of pyridinium chlorochromate in 200 mL of methylene chloride is added rapidly at room temperature a solution of 11.6 g (0.1 mol) of 1-heptanol in 100-150 mL of dichloromethane. A black precipitate is formed shortly. After 2 h, the mixture is diluted with 5 volumes of anhydrous ether, the solvents are decanted, and the black solid is washed twice with ether. The organic solution is filtered through Florisil (magnesium silicates), and the solvent is evaporated at reduced pressure. Heptanal (10.1 g), bp 153 °C , is obtained in 78% yield. 

Triol 984 is converted to acetonide 985 and the free hydroxyl group is sequentially oxidized to an aldehyde (986) with pyridinium chlorochromate and then to an acid under Jones conditions. Acidic workup furnishes the hydroxy butyrolactone 987. Treatment of THP-protected butyrolactone 988 with methyl Grignard reagent affords diol 989. Removal of the THP group, tosylation of the primary alcohol, and cyclization under basic conditions provides epoxide 990. Opening the oxirane ring with 2-(l,3-butadienyl)magnesium chloride in the presence of... 

---