methyl (3R)-3-[(2-bromo-1-oxooctyl)oxy]-tetradecanoate → (2R)-5-hexyl-4-hydroxy-2-undecyl-2,3-dihydropyran-6-one

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Reaction Steps

While the α-halo ester III and the reactive species generating reagent can be combined or added in any sequence, it has been found that when the reactive species generating reagent is a Grignard reagent a simultaneous addition of the α-halo ester III and the Grignard reagent is particularly preferred. For example, simultaneous addition of 13.6 mL solution of 30.7 mmol of methyl (3R)-3-[(2-bromo-1-oxooctyl)oxy]-tetradecanoate in tetrahydro-furan (THF) and 3 equivalents of tert-butyl magnesium chloride in 86 mL of THF over a one hour period to a 60° C. reaction vessel containing about 10 mL of THF solvent resulted in 97% yield (A.N., i.e., area normalized) of (6R)-3-hexyl-4-hydroxy-6-undecyl-5,6-dihydropyran-2-one when the crude product was analyzed by a gas chromatography 1 hr after the complete addition of reagents.

Provenance & Evidence