General Procedure for Mukaiyama Oxidation

Initially, the alcohol is transformed into an alkoxymagnesium halide, according to two alternative protocols  

2-3 equivalents of r-butanol, either neat or in a ca. 0.2-0.6 M solution in dry THF, are mixed with ca. 0.98-1.0 equivalents of a Grignard reagenta per equivalent of r-butanol, the Grignard reagent being contained in a ca. 0.2-0.4 M solution in THF. After at least 3 min., the resulting solution of r-butoxymagnesium bromide is mixed with 1 equivalent of the alcohol contained in a ca. 0.1-1.7 M solution in THF.d After at least 10 min., ADD is added. 

The oxidation of this very sensitive substrate can be carried out by the Mukaiyama procedure with a 81% yield in a scale greater than 100 g. 

The obtention of this very labile product, containing an allylstannane and an aldehyde in the same molecule, was tried unsuccessfully using many oxidizing conditions. Eventually, this product could be prepared following a Mukaiyama oxidation. The basic conditions were essential to avoid protiodestannylation. The product could not withstand chromatography 

After trying many oxidizing conditions, it was found that the Mukaiyama procedure is the most suitable. The oxidation also succeeds employing a Swern oxidation, although the corresponding work-up is more difficult. 

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