A transition-metal-free synthesis of vinyl sulfones, utilizing sodium sulfinates and cinnamic acids through tandem cross-decarboxylative/coupling reactions, has been developed.
A palladium-catalyzed multicomponent reaction (MCR) of propargylic carbonates with isocyanides is reported. Remarkably, the orderly insertion of isocyanides affords two types of valuable N-heterocyclic products (Z)-6-imino-4,6-dihydro-1H-furo[3,4-b]pyrrol-2-amines and (E)-5-iminopyrrolones in high yields. Systematic analysis of the reaction conditions indicates that the selectivity of these N-heterocyclic products can be controlled by ligands and temperature.
Under copper-catalyzed or base-promoted conditions, a wide range of ene-yne-ketones react with H-phosphonates to afford various phosphorylated furans in good yields. A copper carbene generation or a Michael addition is proposed as the key step in the selective construction of the Csp(3)-P or Csp(2)-P bond, which is supported by carbene capture reactions and interval (31)P NMR experiments. Furthermore, this method features inexpensive metal catalysts, no usage of oxidant, and high atom economy, which make it attractive and practical.
A highly selective palladium-catalyzed carbonylation of Csp(2)-H bonds with aromatic oximes for the synthesis of benzo[d][1,2]oxazin-1-ones and 3-methyleneisoindolin-1-ones has been developed. Interestingly, we found that the N-OH group of the oximes could be used as a directing group and/or an internal oxidant under different conditions. This transformation is supposed to proceed through a hydroxyl-directed ortho-Csp(2)-H carbonylation or activation of vinyl Csp(2)-H bond/ortho-Csp(2)-H carbonylation process. The uses of readily available starting materials, atmospheric pressure of carbon monoxide, as well as operational simplicity make this practical and atom-economical method particularly attractive.
A palladium-catalyzed, environmentally
friendly dioxygenation reaction
of simple alkenes has been developed that enabled rapid assembly of
valuable α-hydroxy ketones with high atom economy. Notably,
control experiments and 18O isotope-labeling experiments
established that H2O2 played a dominant dual
role in this transformation.
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