Highly enantioselective [4 + 2] cycloaddition reactions catalyzed by a chiral N-methyl-oxazaborolidinium cation.
The reaction of lithium aryl borohydrides with salts of beta-amino alcohols provides a new route for the synthesis of oxazaborolidines. This method also leads to the first synthesis of hitherto elusive N-methyl oxazaborolidine cations, specifically the cationic proline derivative 3. Compound 3 is a strong chiral Lewis acid which is very effective for catalysis of [4 + 2]-cycloaddition reactions in good yield and with high enantioselectivity. Several diverse examples illustrate the scope of these catalytic reactions.
Canales
Eda
E
Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, USA.
Corey
E J
EJ
D000466:Alkadienes / Q000737:chemistry; D000605:Amino Alcohols / Q000737:chemistry; D001372:Aza Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D001896:Boron Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D002412:Cations / Q000737:chemistry; D003500:Cyclization; D003517:Cyclopentanes / Q000737:chemistry; D013237:Stereoisomerism
D000466:Alkadienes; D000605:Amino Alcohols; D001372:Aza Compounds; D001896:Boron Compounds; D002412:Cations; D003517:Cyclopentanes; C013905:cyclopentenone