Reduction of Acetals, Ketals, Hemiacetals, Hemiketals, and Orthoesters

Reduction of Acetals, Ketals, Hemiacetals, Hemiketals, and Orthoesters 

The ketals of both aryl and alkyl ketones can be reduced to the methylene derivatives in good yields (Eqs. 301 and 302),479 

This reduction technique also applies to the benzaldehyde acetals of sugars with reduction of the benzaldehyde acetals taking place in preference to reduction of the anomeric acetal (Eq. 305).497 

A highly useful and important regioselective reduction of substrate 84 leads to a mixture of 3-hydroxy ethers 85 and 86 in a 32 1 ratio (Eq. 306). Compound 85 is further converted to the anti-influenza drug oseltamivir phosphate, better known as Tamiflu .498 

The triethylsilane reduction of the peroxy ethyl ether shown in Eq. 307 takes place at the C-0 bond of the methyl ether without reduction of either the iodide or the peroxide functionalities (Eq. 307).499In contrast, a bridged peroxy ether undergoes reduction of both C-0 bonds of the peroxide linkage rather than at the ether bridge (Eq. 308) 499 

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