10.1002/ejoc.201800794
European Journal of Organic Chemistry
COMMUNICATION
(30 mL) and aqueous HCl (0.1 M, 20 mL). The aqueous layer was
extracted with CH2Cl2 (3 × 20 mL) and the combined organic phases
were dried over Mg2SO4, filtered and concentrated. The crude product
was purified by column chromatography.
Procter, R. A., Flowers, II, T. Skrydstrup, Organic Synthesis using
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General procedure B: SmI2–tBuOH–LiBr mediated reduction of urea
carbonyls in barbiturates to form cyclic hemiaminals: To an oven-
dried vial charged with anhydrous LiBr (868 mg, 10.0 mmol, 100 equiv)
was added freshly prepared SmI2 (0.5 mmol, 5.0 mL, 0.1 M, 5 equiv) in
THF, under a nitrogen atmosphere. The solution was stirred for 30 min at
room temperature. An oven-dried vial containing a stir bar was charged
with barbiturate (0.1 mmol, 1 equiv) and placed under a positive pressure
of nitrogen. THF (0.05 M, 2.0 mL) and tBuOH (10 equiv) were then
added, followed by the addition of the mixture of SmI2 and LiBr with
vigorous stirring. After the specified time (8 h), the reaction was
quenched by bubbling air through the mixture before dilution with CH2Cl2
(30 mL) and aqueous HCl (0.1 M, 20 mL). The aqueous layer was
extracted with CH2Cl2 (3 × 20 mL) and the combined organic phases
were dried over Mg2SO4, filtered and concentrated. The crude product
was purified by column chromatography.
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Acknowledgements
We thank the EPSRC (EPSRC Established Career Fellowship to
D.J.P.), the Leverhulme Trust (Research Fellowship to D.J.P.),
and the University of Manchester (President’s Scholarship to
H.H.) for funding.
Keywords: Reduction • Samarium • Urea • Single Electron
Transfer • aminal
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