1,2-disubstituted or monosubstituted alkenes. Aromatic compounds may be reduced with TFA and triethylsilane. Substituted furans are reduced to tetrahydrofuran derivatives in high yield. A synthesis of (+)-estrone relies on selective hydrosilane reduction of a conjugated alkene as a key step. The ketone carbonyl and isolated double bond are unaffected under the conditions shown. Ether cleavage Acetals, ketals, and aminals are reduced in the presence of hydrosilanes and acid. Site-selective reduction of acetals and ketals whose oxygens are inequivalent have been reported—the example below is used in a synthesis of Tamiflu. Other functional groups that have been reduced with hydrosilanes include amides, and α,β-unsaturated esters enamines, imines, and azides. Safety Trifluoroacetic acid, often used in these reductions, is a strong, corrosive acid. Some hydrosilanes are pyrophoric. References Organic reactions