Benzynes were generated from o-(trimethylsilyl)phenols using nonafluorobutanesulfonyl fluoride (NfF) by a domino process, i.e., the nonaflation of the phenolic hydroxyl group of o-(trimethylsilyl)phenols by NfF followed by the attack of the produced fluoride ion on the trimethylsilyl group. The generated benzyne immediately underwent various reactions to give polysubstituted benzenes.
Enantioselective Spirocyclopropanation of <i>para</i>-Quinone Methides Using Ammonium Ylides
作者:Lukas Roiser、Mario Waser
DOI:10.1021/acs.orglett.7b00869
日期:2017.5.5
The use of Cinchonaalkaloid-based chiral ammonium ylides allows for the first highlyenantioselective and broadly applicable spirocyclopropanation reactions of para-quinone methides. This strategy provides a straightforward protocol toward the chiral spiro[2.5]octa-4,7-dien-6-one skeleton, which is a frequently found structural motif in important biologically active molecules.
It′s just a phase: The title reaction sequence of para‐quinonemethides (p‐QMs) has been developed with malonates under phase‐transfer catalysis. The reaction also offers an alternative route to asymmetric construction of diarylmethine stereocenters in excellent enantioselectivities and high yields.
Aerobicoxidative dimerization of hydroxystilbenoids is described. A Cr–salen complex catalyzed the dimerization of hydroxystilbenoids in 1,1,1,3,3,3-hexafluoroisopropanol to form compounds comprising a natural product-like scaffold (quadrangularin) or its precursor depending on the aromatic substituents. The addition of a catalytic amount of scandium triflate [Sc(OTf)3] to the reaction system altered