The Catalytic Asymmetric Intermolecular Prins Reaction
C. David Díaz-Oviedo, Rajat Maji and Benjamin List*
*Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany,
Email: list
kofo.mpg.de
C. D. Díaz-Oviedo, R. Maji, B. List, J. Am. Chem. Soc., 2021, 143, 20598-20604.
DOI: 10.1021/jacs.1c10245
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Abstract
An enantioselective intermolecular Prins reaction of styrenes and paraformaldehyde provides 1,3-dioxanes, using confined imino-imidodiphosphate (iIDP) Brønsted acid catalysts via a concerted, highly asynchronous addition of an acid-activated formaldehyde oligomer to the olefin. The enantioenriched 1,3-dioxanes can be transformed into the corresponding optically active 1,3-diols.
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proposed mechanism
General Procedure: iIDP-Catalyzed Prins reaction of aryl olefins and paraformaldehyde
An oven-dried glass vial was charged with paraformaldehyde (18.8 mg, 0.625 mmol, 2.5 equiv.), (S,S)-iIDP catalyst (62.5 µmol, 2.5 mol%), dry cyclohexane (depending on the concentration, indicated in each case, see supporting information), and olefin (0.25 mmol, 1 equiv.) under Ar. Then, the mixture was vigorously stirred at rt for a certain time (indicated in each case). The reaction was stopped by adding distilled water (10 mL), followed by extraction with MTBE (3 x 20 mL). The combined organic layers were washed with brine (1 x 10 mL), then dried over anhydrous Na2SO4, filtered and concentrated under reduced pressure. Purification by flash column chromatography on silica gel (n-pentane/MTBE mixtures) afforded the corresponding enantioenriched 4-substituted-1,3-dioxane product.
A General Catalytic Asymmetric Prins Cyclization
L. Liu, P. S. J. Kaib, A. Tap, B. List, J. Am. Chem. Soc., 2016, 138, 10822-10825.
Key Words
organocatalysis, O-heterocycles, Prins reaction
ID: J48-Y2021
