The rate and enantioselectivity of chiral NHC-catalyzed asymmetric acylation of alcohols with an adjacent H-bond donor functionality are remarkably enhanced in the presence of a carboxylate cocatalyst. The degree of the enhancement is correlated with the basicity of the carboxylate. With a cocatalyst and a newly developed electron-deficient chiral NHC, kinetic resolution and desymmetrization of cyclic diols and amino alcohols were achieved with extremely high selectivity (up to s = 218 and 99% ee, respectively) at a low catalyst loading (0.5 mol %). This asymmetric acylation is characterized by a unique preference for alcohols over amines, which are not converted into amides under the reaction conditions.

A chiral organic base catalyst with halogen-bonding-donor functionality has been developed. This quinidine-derived acid/base catalyst smoothly promoted the asymmetric Mannich reaction of malononitrile and various N-Boc imines with up to 98% ee. The cooperative interaction with both substrates was responsible for the high activity that allowed a reduction of the catalyst amount to 0.5 mol%.

Homo-and cross-[4+ +2] cycloadditions of 2-alkenylindoles,c atalyzedb yc ationic halogen-bond donors,w ere developed. Under mild reaction conditions,3 -indolyl-substituted tetrahydrocarbazole derivatives were obtained in good to excellent yields.Experimental and quantum calculation studies revealed that the electrophilic activation of 2-alkenylindoles was achieved by C À I···p halogen bonds.

Säure statt Base: Die kinetische Racematspaltung von sekundären Alkoholen durch Acylierung wurde nicht wie üblich unter basischen Bedingungen, sondern mithilfe eines chiralen Brønsted‐Säure‐Katalysators erzielt. Eine Bandbreite von funktionellen Gruppen wie Aldehyde, Carbonsäuren und Enoate wird toleriert. Der Selektivitätsfaktor (s) beträgt bis zu 215 bei Umgebungstemperatur.

Depending on the N-heterocyclic carbene catalyst utilized, α-unbranched aldehydes selectively provided amides, esters, or carboxylic acids through oxidation by NCS. The α-unbranched aldehyde underwent these reactions chemoselectively in the presence of an aromatic or α-branched aldehyde.

Bis(imidazolidine)iodobenzene (I-Bidine) was designed as an organocatalyst based on previously reported imidazolidine-or oxazolidine-containing chiral metal catalysts. I-Bidine showed catalytic activity for the Michael/Henry reaction of thiosalicyl aldehydes with nitroalkenes to give optically active thiochromanes with moderate enantiomeric excesses.

Chiral organic base catalyst with halogen bond donor functionality catalyzed asymmetric Mannich-type reaction of malononitrile with αketiminoesters to produce α,α-disubstituted α-amino acid derivatives in good yields with high enantioselectivities. The malononitrile-derived amino acid was smoothly transformed to chiral aminomalonate without loss of ee. Keywords: Halogen bond; Mannich-type reaction;Unnatural amino acid; α-Ketiminoester; Iodine 4 a was obtained quantitatively with 82% ee (entry 2).Cinchonine-derived 1 c and quinidine-derived 1 d [7]

A stable, hypervalent cyclic dibenzoiodolium salt acted as a strong halogen bonding (XB)-donor catalyst for [4 + 2] cycloaddition of 2-alkenylindoles, and not as an oxidizing agent. The cross-[4 + 2] cycloaddition of 2-vinylindoles with 2-alkenylindoles was catalyzed smoothly by the hypervalent cyclic dibenzoiodolium triflate catalyst to give the tetrahydrocarbazoles in up to 99 % yield with 17 : 1 diastereoselectivity. The hypervalent cyclic dibenzoiodolium salt was also applicable to the Povarov reaction of 2-vinylindole with N-p-methoxyphenyl (PMP) imine to give the indolyl-tetrahydroquinoline in 83 % yield.