The concept of bifunctional catalysis, wherein both partners a bimolecular reaction are simultaneously activated, is very powerful for designing efficient asymmetric catalysts. Catalytic processes indispensable producing enantiomerically enriched compounds in modern organic synthesis, providing more economical and environmentally benign results than methods requiring stoichiometric amounts chiral reagents. Extensive efforts this field have produced many catalysts, now number reactions can be...

A unique synthetic utility of a Cp*CoIII catalyst in comparison with related Cp*RhIII catalysts is described. C2-selective indole alkenylation/annulation sequence proceeded smoothly catalytic amount [Cp*CoIII(C6H6)](PF6)2 complex and KOAc. Intramolecular addition an alkenyl-Cp*Co species to carbamoyl moiety gave pyrroloindolones 58–89% yield one pot. Clear difference was observed between the activity those complexes, highlighting nucleophilic organocobalt species. The catalysis also suitable...

Active without activation: In an inexpensive and atom-economical approach to CH bond functionalization, a cationic CoIII complex (see scheme) was used generate nucleophilic organometallic species in situ additional activating reagents. Under these conditions, aryl bonds underwent efficient addition polar electrophiles, including α,β-unsaturated N-acyl pyrroles as β-substituted ester amide surrogates.

Abstract High‐valent (pentamethylcyclopentadienyl)cobalt(III) [Cp*Co(III)] catalysts were found as inexpensive alternatives to (pentamethylcyclopentadienyl)rhodium(III) [Cp*Rh(III)] in the field of C—H bond functionalization, and applied a variety transformations. In this review, after discovery early examples Cp*Co(III)‐catalyzed functionalization are summarized, unique reactivity selectivity Cp*Co(III) differences between cobalt rhodium catalysis intensively discussed. Such assumed be...

Abstract The readily available carbonyl(pentamethylcyclopentadienyl)cobalt diiodide complex [Cp*Co(CO)I 2 ] was successfully utilized as the precursor of a cationic cobalt(III) active catalyst for directed CH bond functionalization. Cp*Co(CO)I (2.5–1.25 mol%), in combination with silver hexafluoroantimonate (AgSbF 6 ) and potassium acetate (KOAc), efficiently catalyzed C‐2 selective amidation indoles sulfonyl azides, corresponding products were obtained 85–98 % yield. magnified image

Catalytic asymmetric direct Mannich-type reactions of α-substituted nitroacetates using a new bench-stable homodinuclear Ni2−Schiff base 1b complex are described. The Ni2−1b gave Mannich products, precursors for anti-α,β-diamino acids with an α-tetrasubstituted carbon stereocenter, in >99−91% ee. was also applicable to malonates and β-keto ester, giving products high stereoselectivity (up 99% ee, dr >97:3). Preliminary mechanistic studies suggested that the dinuclear Ni metal centers had key...

The synthesis of isoquinolines by site-selective C-H activation O-acyl oximes with a Cp*Co(III) catalyst is described. In the presence this catalyst, various unsymmetrically substituted selectively occurred at sterically less hindered site, and reactions terminal as well internal alkynes afforded corresponding products in up to 98 % yield. Whereas catalyzed system proceeded high site selectivity (15:1 20:1), use Cp*Rh(III) catalysts led low selectivities and/or yields when unsymmetrical were...

Abstract The unique reactivity of [Cp*Co III ] over [Cp*Rh was demonstrated. A cationic catalyst promoted direct dehydrative CH allylation with non‐activated allyl alcohols, thus giving C2‐allylated indoles, pyrrole, and phenyl‐pyrazole in good yields, while analogous catalysts were not effective. high γ‐selectivity C2‐selectivity indicated that the reaction proceeded by directing‐group‐assisted metalation. DFT calculations suggested γ‐selective substitution metalation insertion a CC...

A highly enantioselective catalytic asymmetric access to 3-aminooxindoles with a tetrasubstituted carbon stereocenter is described. 1-2 mol % of homobimetallic (R)-Ni(2)-Schiff base 1 catalyzed the amination 3-substituted oxindoles azodicarboxylates give (R)-products in 99-89% yield and 99-87% ee. Reversal enantiofacial selectivity was observed between bimetallic monometallic Schiff complexes, (R)-Ni-Schiff 2c gave (S)-products 98-80% Transformation products into an optically active oxindole...

Abstract Recent advances in Cp x M III catalysis (M=Co, Rh, Ir) have enabled a variety of enantioselective C(sp 2 )−H functionalization reactions, but 3 is still largely unexplored. We describe an asymmetric amidation thioamides using achiral Co /chiral carboxylic acid hybrid catalytic system, which provides easy and straightforward access to chiral β‐amino thiocarbonyl carbonyl building blocks with quaternary carbon stereocenter.

Cooperative catalysis has proven to be a powerful strategy for realizing high reactivity and selectivity in asymmetric transformations. A variety of cooperative catalysts have been developed over the last two decades. In this feature article, recent advances from our research on catalysis, focusing dinuclear Schiff base are described. Design their applications several C–C C–N bond-forming reactions under simple proton transfer conditions with perfect atom-economy discussed detail.

Hybrid catalyst systems to achieve acceptorless dehydrogenation of N-heterocycles and tetrahydronaphthalenes—model substrates for liquid organic hydrogen carriers—were developed. A binary hybrid catalysis comprising an acridinium photoredox a Pd metal was effective the N-heterocycles, whereas ternary catalyst, thiophosphoric imide organocatalyst achieved tetrahydronaphthalenes. These allowed 2 molar equiv H2 gas release from six-membered tetrahydronaphthalenes under mild conditions, i.e.,...

Enantioselective C–H functionalization is a powerful tool for synthesizing chiral molecules. In the past few years, combination of high-valent group 9 metals with achiral Cpx ligands and carboxylic acids (CCA) has emerged as promising catalytic system to enable selective cleavage enantiotopic bonds. This Perspective summarizes background, catalyst design, applied reactions in detail, followed by discussion future directions.

Abstract Among sulfoximine derivatives containing a chiral sulfur center, benzothiadiazine‐1‐oxides are important for applications in medicinal chemistry. Here, we report that the combination of an achiral cobalt(III) catalyst and pseudo‐ C 2 ‐symmetric H 8 ‐binaphthyl carboxylic acid enables asymmetric synthesis from sulfoximines dioxazolones via enantioselective C−H bond cleavage. With optimized protocol, with several functional groups can be accessed high enantioselectivity.

No preactivation of the alcohol substrates is required in allylic, propargylic, and benzylic aminations catalyzed by a combination commercially available Bi(OTf)3 KPF6, mostly at room temperature (see scheme). The substitution reactions readily accessible alcohols with sulfonamides, carbamates, carboxamides give desired amine products up to 99 % yield.

An anti-selective direct catalytic asymmetric Mannich-type reaction is described. The Et2Zn/(S,S)-linked-BINOL 1 = 4/1 complex promoted a of 2-hydroxy-2‘-methoxyacetophenone (2) and N-diphenylphosphinoyl imines 3. Using as little 0.25−1 mol % the catalyst, we obtained Mannich adducts 4 in excellent yield (up to 99%), diastereoselectivity (anti/syn up >98/2), enantiomeric excess >99.5%). anti-selectivity present system complementary that observed using previously reported methods, providing...

syn-Selective catalytic asymmetric nitro-Mannich reactions using a heterobimetallic Cu/Sm/Schiff base complex are described. The present method is complementary to the previously reported methods, and products were obtained in high syn-selectivity (>20:1), yield (99−62%), enantioselectivity (98−83% ee). Both Cu Sm metals, aligned suitably dinucleating Schiff ligand, essential realize syn-selectivity.

The catalytic enantioselective meso-epoxide ring opening reaction with phenolic oxygen nucleophile (4-methoxyphenol) is described for the first time herein. This was found to be promoted by (R)-GaLB (Ga = gallium, L lithium, B (R)-BINOL), giving a variety of epoxide products in good high ee (67−93% ee). However, chemical yield only modest (yield 31−75%), despite use more than 20 mol % GaLB. due undesired ligand exchange between BINOL and 4-methoxyphenol, which resulted decomplexation...

Catalytic asymmetric 1,4-additions of 3-substituted oxindoles to β-aryl, β-heteroaryl, and β-alkenyl nitroalkenes are described. A new homodinuclear Mn2(OAc)2−Schiff base 1 complex was required realize high diastereo- enantioselectivity. Mn2(OAc)2−1 (1−5 mol %) promoted the in 99−83% yield, 96−85% ee, >30:1−5:1 dr at room temperature, providing useful chiral building blocks for synthesis β-aminooxindoles with vicinal quaternary/tertiary carbon stereocenters.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStructure of maitotoxinMichio Murata, Hideo Naoki, Takashi Iwashita, Shigeki Matsunaga, Masahiro Sasaki, Akihiro Yokoyama, and Takeshi YasumotoCite this: J. Am. Chem. Soc. 1993, 115, 5, 2060–2062Publication Date (Print):March 1, 1993Publication History Published online1 May 2002Published inissue 1 March 1993https://pubs.acs.org/doi/10.1021/ja00058a075https://doi.org/10.1021/ja00058a075research-articleACS PublicationsRequest reuse permissionsArticle...

The full details of a catalytic asymmetric syn-selective nitro-Mannich reaction promoted by heterobimetallic Cu/Sm/dinucleating Schiff base complexes are described, demonstrating the effectiveness transition metal/rare earth metal bifunctional catalysis. first-generation system prepared from Cu(OAc)2/Sm(O-iPr)3/Schiff 1a = 1:1:1 with an achiral phenol additive was partially successful for achieving reaction. substrate scope and limitations remained problematic. After mechanistic studies on...

Full details of our newly developed catalyses with asymmetric zinc complexes as mimics class II zinc-containing aldolase are described. A Et(2)Zn/(S,S)-linked-BINOL complex was and successfully applied to direct catalytic aldol reactions hydroxyketones. 1 = 2/1 system initially developed, which efficiently promoted the reaction 2-hydroxy-2'-methoxyacetophenone (7d). Using mol % (S,S)-linked-BINOL 2 Et(2)Zn, we obtained 1,2-dihydroxyketones syn-selectively in high yield (up 95%), good...