Visible-light-induced [6+4] cycloaddition reactions of ortho-quinone methides have been developed. The reaction of ortho-quinone methides with pentafulvenes in the presence of a thioxanthylium photoredox catalyst afforded benzo[b]cyclopenta[e]oxepines. The present reaction...
An organocatalytic methodology toward the atroposelective construction of axially chiral nonsymmetric biaryltriols has been successfully developed. Quinine-derived thiourea-catalyzed intramolecular reaction through VQM (vinylidene ortho-quinone methides) intermediate enabled efficient access to...
A highly efficient base-mediated diastereoselective [4+1] cycloaddition of ortho-tosylaminophenyl-substituted p-QMs with 3-chlorooxindoles has been developed to afford 3,2’-pyrrolidinyl spirooxindoles in high yields with high diastereoselectivity through domino 1,6-addition/cyclization sequence. This...
Regioselective syntheses of N1 and N2 substituted triazoles via 1,6-addition of 1,2,3-NH triazole with p-QM were developed under mild reaction conditions. Isomerization of N1 to N2 substituted triazoles was also achieved in the presence of AlCl3.
Chemoselective sulfonylation and isonitrilation reactions for the divergent synthesis of valuable diarylmethyl sulfones and isonitrile diarylmethanes starting from easy-to-synthesize para-quinone methides (p-QMs) and commercially abundant p-toluenesulfonylmethyl isocyanide (TosMIC) by using respectively zinc iodide and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as catalysts were developed. The distinguishing feature of this method is that TosMIC plays a dual role from the same substrates in the reaction: as a sulfonyl source or as an isonitrile source. The synthetic utility of this protocol was also demonstrated in the synthesis of difluoroalkylated diarylmethane 5 and diarylmethane ketone derivatives 6 and 7, which are important core structures in natural products and medicines.
Catalytic asymmetric [2 + 4] cycloadditions of 3-vinylindoles with ortho-quinone methides and their precursors were carried out in the presence of chiral phosphoric acid to afford a series of indole-containing chroman derivatives with structural diversity in overall high yields (up to 98%), good diastereoselectivities (up to 93:7 dr) and moderate to excellent enantioselectivities (up to 98% ee). This approach not only enriches the chemistry of catalytic asymmetric cycloadditions involving 3-vinylindoles but is also useful for synthesizing chiral chroman derivatives.
Tropylium Salt-Promoted Vinylogous Aza-Michael Addition of Carbamates to para-Quinone Methides: Elaboration to Diastereomerically Pure α,α′-Diarylmethyl Carbamates