[3383-21-9] · C14H20O2 · 3,5-Di-t-butyl-1,2-benzoquinone · (MW 220.31)
(reacts with primary amines to give different products depending on the alkyl substituent: benzoxazoles from primary amines and a-amino acids; ketones from s-alkyl primary amines; dioxazepines from cyclopropylamines; aromatic aldehydes from vic-aminobenzyl alcohols; skatole from tryptophan)
Alternate Name: DTBBQ.
Physical Data: mp 114-115 °C.
Solubility: sol most organic solvents; insol water.
Form Supplied in: dark red needles; commercially available.
Purification: recrystallization from toluene or by vacuum sublimation.
Handling, Storage, and Precautions: avoid exposure to light; toxicity unknown.
As a result of the steric hindrance caused by two t-butyl groups, the reactions are centered at the less hindered carbonyl, producing an unstable quinoneimine which is prone to a spontaneous aromatization. All reactions occur under mild conditions. In several reactions DTBBQ mimics pyridoxal.8
Primary alkyl primary amines, e.g. benzylamine1 and ethanolamine,2 react with DTBBQ to give benzoxazole derivatives via a quinoneimine and a Schiff base that undergoes cyclization and dehydrogenation with DTBBQ present in excess (eq 1).
s-Alkyl primary amines undergo oxidative deamination (Corey's reaction) to give ketones produced in 84-97% yield. A small quantity of a phenoxazinone derivative is responsible for the pink color of the reaction mixture (eqs 2 and 3).1,3
The Vaclav Horak & Youco Mermersky Georgetown University, Washington, DC, USA
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Vaclav Horak & Youco Mermersky
Georgetown University, Washington, DC, USA