Epoxidation using Corey reagent

One of the important functionalizations of the keto function is the epoxidation using the Corey reagent (dimethylsulfoniumethylide in DMSO and THF) as reported by Qelas and Gelas (41,42) (Scheme 10). 

In a second synthesis of LTB4, Corey s group made use of the excellent method of asymmetric epoxidation developed by Sharpless and co-workers to obtain an optically active epoxy alcohol (Scheme 3.11). In this sequence, the Wittig reagent 27 seems to condense much more cleanly with (S)-21a than did 24 (Scheme 3.10). The key and very elegant step in the synthesis was the hydrolysis and rearrangement of the intermediate 28, which undergoes a very... 

As an alternative to Corey s reagent, methylene dibromide in the presence of Li may be used to convert aldehydes and ketones to epoxides in 35-90% yield. ... 

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