The asymmetric dihydroxylation (AD) of o-cyano cinnamates and styrene derivatives leads to efficient construction of chiral phthalide frameworks in high optical purities. This unique reaction is characterized by unusual synergism between CN and osmate groups resulting in rate enhancement of the AD process. The method is amply demonstrated by the synthesis and the structural/stereochemical assignment of the natural products.

A formal cycloaddition reaction for the synthesis of biologically and pharmaceutically important carbazolequinones via the annulation of aminoquinones with arynes has been developed. This practical and metal-free cascade reaction proceeds through successive C-C/C-N bond formations. Moreover, this novel method has been utilized for the concise synthesis of bioactive murrayaquinone A and koeniginequinone B and their analogues.

Transition-metal-free inverse electron-demand aza Diels-Alder and domino [4+2]/[2+2] cycloaddition reaction of arynes and N-sulfonyl ketimines has been demonstrated. This novel, mild, and efficient protocol allows rapid access to isothiazole dioxide-fused dihydroquinoline or dihydrocyclobutaquinoline derivatives selectively by simply varying the equivalents of aryne precursors. The application of this method has been amply illustrated in the synthesis of 2,4-diarylquinolines.

The transition-metal-free multicomponent coupling of arynes, anilines, and ethylglyoxylate, proceeding via an inverse electron-demand aza Diels-Alder cycloaddition and N-arylation, has been demonstrated. This protocol allows rapid access to N-aryl dihydrophenanthridine derivatives in moderate to high yields at room temperature from readily available starting materials. In addition, an unprecedented fluoride induced annulation of ethyl(arylimino)acetates led to the formation of highly functionalized oxoimidazolidine derivatives in good yields under mild conditions.

No abstract

A novel "one-pot" aryne transformation is described that affords various 4-quinolone derivatives without recourse to transition-metal catalysis. Arynes react with aza-Morita-Baylis-Hillman (AMBH) adducts through a cascade sequence involving an insertion/cyclization/ene reaction process to afford 4-quinolones in high yields with a broad substrate scope under mild reaction conditions. Essentially, an umpolung of reactivity at the β carbon of α,β-unsaturated ketone has been achieved by an inverse electron demand aryne-ene reaction to provide a C-arylated product.

A simple, organocatalytic procedure for the direct oxidative esterification of a variety of aromatic aldehydes with alcohols has been described that affords the corresponding aromatic esters in high yields. The method employs N-heterocyclic carbenes as catalysts and molecular O 2 as an oxidant under ambient conditions.

A ZnII complex of a C2‐chiral bisamidine‐type sp2N bidentate ligand (LR) possessing two dioxolane rings at both ends catalyzes a highly efficient quinone asymmetric Diels‐Alder reaction (qADA) between o‐alkoxy‐p‐benzoquinones and 1‐alkoxy‐1,3‐butadienes to construct highly functionalized chiral cis‐decalins, proceeding in up to a >99:1 enantiomer ratio with a high generality in the presence of H2O (H2O:ZnII=4–6:1). In the absence of water, little reaction occurs. The loading amount of the chiral ligand can be minimized to 0.02 mol % with a higher Zn/LR ratio. This first success is ascribed to a supramolecular 3D arrangement of substrates, in which two protons of an “H2O‐ZnII” reactive species make a linear hydrogen bond network with a dioxolane oxygen atom and one‐point‐binding diene; the ZnII atom captures the electron‐accepting two‐points‐binding quinone fixed on the other dioxolane oxygen atom via an n‐π* attractive interaction. The mechanisms has been supported by 1H NMR study, kinetics, X‐ray crystallographic analyses of the related ZnLR complexes, and ligand and substrate structure‐reactivity‐selectivity relationship.