Divergent NHC-Catalyzed Oxidative Transformations of 3-Bromoenal: Selective Synthesis of 2<i>H</i>-Pyran-2-ones and Chiral Dihydropyranones
作者:Gang Wang、Xia Chen、Gaohan Miao、Weijun Yao、Cheng Ma
DOI:10.1021/jo400950j
日期:2013.6.21
A selectivesynthesis of either 2H-pyran-2-ones (4) or chiral dihydropyranones (6) from the same substrates of 3-bromoenals and 1,3-dicarbonyl compounds upon oxidative N-heterocyclic carbene catalysis is presented. It is shown that the oxidative transformation of 3-bromoenals under NHC catalyst can be well controlled to proceed through two pathways, i.e., elimination of reducible β-bromide or by an
An N-heterocyclic-carbene-catalyzed asymmetric formal [3+2] annulation reaction of isatin N-Boc ketimines (Boc = tert-butyloxycarbonyl) and 3-bromoenals was developed for the construction of spiro[indoline-3,2′-pyrrole] derivatives with one quaternary chiral center in good yields (up to 81 % yield) with excellent enantioselectivity (up to 99 % ee).
A metal-free cascade reaction strategy has been developed for the synthesis of novel polycyclic 2-formylthiophenes from β-halo-α,β-unsaturatedaldehydes and 1,4-dithiane-2,5-diol. Recyclable polymer supported organic base was used to perform the reaction process. This synthetic protocol was applied to synthesize several novel polycyclic thiophenes including steroidal D-ring annelated thiophene. Our
Chiral Spirooxindole–Butenolide Synthesis through Asymmetric N-Heterocyclic Carbene-Catalyzed Formal (3 + 2) Annulation of 3-Bromoenals and Isatins
作者:Chenguang Zheng、Weijun Yao、Yucheng Zhang、Cheng Ma
DOI:10.1021/ol502365r
日期:2014.10.3
By using an N-heterocyclic carbene catalyst bearing a hydroxyl moiety, the asymmetric formal (3 + 2) cyclization of aryl 3-bromoenals and isatins was achieved to produce a series of chiral spirooxindole–butenolides including an alkenyl-substituted compound, which underwent benzannulations with benzynes to form intriguing spirocyclic scaffolds.
into each of the furan units, are rapidly and efficiently synthesized by de novo metal-free synthesis of α-bi(arylfuran) monomers. The characterization of α-oligo(arylfuran)s demonstrates that photoelectric properties of coplanar α-oligo(arylfuran)s can be tuned through varying aryl groups with different electrical properties. These novel α-oligo(arylfuran)s have good hole transport capacity and can function