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Deoxidation/reduction of aromatic esters, α-diketones, acyloins, and epoxides to the corresponding bibenzyl products with lithium 4,4′-di-t-butylbiphenyl radical anion

✍ Scribed by Rafik Karaman; James L. Fry

Publisher: Elsevier Science
Year: 1989
Tongue: French
Weight: 208 KB
Volume: 30
Category: Article
ISSN: 0040-4039
DOI: 10.1016/s0040-4039(01)80546-3

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✦ Synopsis

Sonication of aromatic esters, benzil, benwin, cis-and trans-stilbene, and tramstilbene oxide with excess lithium in the presence of catalytic amounts of 4,4'-di-t-butylbiphenyl (DBB) in dry THF afforded bibenzyl derivatives in high yields.

The reactions of esters with alkali metals (Na and K) have been studied for a long time. Alkyl and aryl benwates, for example, react with sodium to give radical anions which can couple and then suffer spontaneous loss of alkoxide to give benzil which in turn undergoes reduction to yield benwin as a final product.'" This procedure has been improved by adding trimethylchlorosilane to the reaction mixture of sodium and ester6

Surprisingly, although the reductions of esters7** and related carbonyl compounds such as ketonesQ*" and aldehydes" with lithium metal in liquid ammonia have been reported, there appears to be no information on the reaction of esters with lithium in inert solvents. Continuing our investigation of the umpolung reactions of carbonyl compounds,'* we have found that aromatic esters undergo facile

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✍ Adalbert Maercker; Ulrich Girreser 📂 Article 📅 1990 🏛 Elsevier Science 🌐 French ⚖ 109 KB

In the reaction of benzil with lithium in the presence of 4,4\*-dit-butylbiphenyl (DBB) tram-stilbene 4 and dilithiobibensyl 5 are intermediates instead of the reported tetralithiobibenayl 2.