Multicomponent Hosomi–Sakurai Reaction on Isosorbide Derivatives

Trimethylsilyl ethers of monoprotected isosorbide derivatives have been subjected to multicomponent Hosomi–Sakurai reactions with allyl trimethylsilane and various aldehydes (aromatic or aliphatic) under the catalysis of trimethylsilyl triflate. This study has allowed for establishing that: (a) the best results are obtained in reactions involving TMS ethers of the endo-OH group; (b) the most suited protecting group is the tert-butyldiphenylsilyl ether. With this ideal substrate, a scope was studied using both aromatic and aliphatic aldehydes. Good yields and excellent diastereoselectivities were typically achieved with aromatic aldehydes, unless they were very encumbered at the ortho position or strongly electron-poor. With simple aliphatic enolizable aldehydes, it may be useful to use an excess of aldehydes because of self-condensation processes. These results open the way to conjugates of bio-based isosorbide with aldehyde-derived fragments, joined through a very stable ether group.