Phenanthrenes Birch reduction

Birch reduction of phenanthrene or 9-alkylphenanthrenes results in tetrahydro derivatives, but 9,10-dihydro derivatives are obtained in high yield by Li/NH3 reduction of phenanthrenes substituted by a 9-trimethylsilyl group (equation I). The trimethylsilyl group of 1 can be removed in quantitative yield with Bu4NF in... 

Photo-Birch reductions. Irradiation of aromatic hydrocarbons in aqueous ucelonilrile in the presence of sodium borohydride and 1,2-, 1,3-, or 1,4-dicyimobenzene with a high-pressure mercury arc results in reduction to dihydro derivatives. Phenanthrene is reduced to 9,10-dihydrophenanthrene (71%), aiillirueene lo 9,10-dihydroanthraccne (70%), and naphthalene to 1,4-... 

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