Sulfoxides, Julia-Lythgoe olefination

Satoh, T., Yamada, N., Asano, T. Ligand exchange reaction of sulfoxides in organic synthesis sulfoxide version of the Julia-Lythgoe olefination. Tetrahedron Lett. 1998, 39, 6935-6938. 

A sulfoxide version of the Julia-Lythgoe olefination is terminated by elimination of vicinal hydroxyl and phenylsulfinyl groups on treatment with BuLi." ... 

The tri-substituted olefin was also prepared by sulfoxide version of the Julia-Lythgoe olefination. The a-branched sulfoxide, cyclohexyl p-tolyl sulfoxide 54 was treated with LDA at -55 °C, then added to the aldehyde in THF to give the adduct 55 in 78% yield, which was a mixture of two diastereomers (L P = 66 34 L is less polar isomer and P is the more polar isomer on silica gel TLC). The mixture of 55 was separated by silica gel column chromatography. The isomers were acetylated separately to give 56 in almost quantitative yield. The 56 was treated with n-BuLi to provide final product 57. The P-isomer gave better yields (90%) than the L-isomer (43%). 

The use of the Julia-Lythgoe olefination with cyclopropylsulfones and cyclopropylsulfoxides for the synthesis of alkylidenecyclopropanes was reported by Bernard and co-workers. The adduct sulfide 60, prepared from sulfide 58, was oxidized to sulfone 61 and sulfoxide 64 by controlling oxidation temperature. Both intermediate 61 and 64 can be further converted to trisubstituted alkene 63 under different reductive condition. 

Marko and co-workers also made an efforts on the modification of the classical Julia-Lythgoe olefination using sulfoxides instead of sulfones. The modified reaction, after in situ benzoylation and Sml2/HMPA- or DMPU-mediated reductive elimination, provides 1,2-di-, tri-, and tetra-substituted olefins in moderate to excellent yields and E/Z selectivity. For example benzoated sulfoxide 67 was obtained by addition of sulfoxide 66 to aldehyde 33, which was subsequently reduced into alkene 68 in 67% yield with E/Z ratio of > 95 1. 

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