Stereoselective double lewis acid/organo-catalyzed dimerization of donor-acceptor cyclopropanes into substituted 2-oxabicyclo[3.3.0]octanes.
A new approach for the dimerization of donor-acceptor cyclopropanes (2-arylcyclopropane-1,1-dicarboxylates) under double-catalysis conditions by treatment with 20 mol % of GaCl(3) and dimethyl 3,5-dimethyl-1-pyrazoline-3,5-dicarboxylate as a specific organocatalyst has been found. Under these conditions, the starting compounds are regio- and stereospecifically converted into polysubstituted 2-oxabicyclo[3.3.0]octanes. Two new rings, one C-O bond, and two C-C bonds are formed in this process, and four stereocenters are thus created. The reaction mechanism was thoroughly studied by NMR spectroscopy, and a number of intermediates were detected.
N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky prosp., 119991 Moscow, Russian Federation.
Roman A
RA
Novikov
Vladimir P
VP
Timofeev
Yury V
YV
Tomilov
D001643:Bridged Bicyclo Compounds / Q000737:chemistry*; D002384:Catalysis; D003521:Cyclopropanes / Q000737:chemistry*; D019281:Dimerization; D058116:Lewis Acids / Q000737:chemistry*; D015394:Molecular Structure; D011720:Pyrazoles / Q000737:chemistry*; D013237:Stereoisomerism
C576306:3,5-dimethyl-1-pyrazoline-3,5-dicarboxylate; D001643:Bridged Bicyclo Compounds; D003521:Cyclopropanes; D058116:Lewis Acids; D011720:Pyrazoles