Publication 2012

▼Conformationallyflexible chiral hypervalent Organoiodine catalysts for enantioselective Oxidative Transformations

Muhammet Uyanik

Kazuaki Ishihara*

J. Synth. Org. Chem., Jpn. 2012, 70(11), 1116–1122.
▷https://www.jstage.jst.go.jp/browse/yukigoseikyokaishi/70/11/_contents/-char/ja/

▼テーラーメイド型超分子触媒の設計

Manabu Hatano

Kazuaki Ishihara*

Chemical Engineering 2012, 57(9), 656-661.
▷http://www.kako-sha.co.jp/volchem.html

▼Baeyer-Villiger Oxidation and Oxidative Cascade Reactions with Aqueous Hydrogen Peroxide Catalyzed by Lipophilic Li[B(C6F5)4] and Ca[B(C6F5)4]

Muhammet Uyanik

Daisuke Nakashima

Kazuaki Ishihara*

Angew. Chem. Int. Ed. 2012, 51(36), 9093-9096.
Article first published online: 15 AUG 2012

▷DOI: 10.1002/anie.201204286

In situ generated lanthanum(III) nitrate alkoxide is a highly active and nearly neutral transesterification catalyst, which can promote non-epimerized transesterification of α-substituted chiral carboxylic esters under reflux conditions.

▼In Situ Generated “Lanthanum(III) Nitrate Alkoxide” as a Highly Active and Nearly Neutral Transesterification Catalyst

Manabu Hatano

Sho Kamiya

Kazuaki Ishihara*

Chem. Commun. 2012, 48, 9465-9467.

▷DOI: 10.1039/C2CC34987F

In situ generated lanthanum(III) nitrate alkoxide is a highly active and nearly neutral transesterification catalyst, which can promote non-epimerized transesterification of α-substituted chiral carboxylic esters under reflux conditions.

▼α-Heterosubstituted beta-Alkylacroleins as Useful Multisubstituted Dienophiles for Enantioselective Diels-Alder Reactions

Akira Sakakura

Hiroki Yamada

Kazuaki Ishihara*

Asian. J. Org. Chem. 2012, 1(2), 133-137.

▷DOI: 10.1002/ajoc.201200054

Building complexity: α-(N,N-Diisopropylcarbamoyloxy)-β-alkylacroleins and α-(acylamino)crotonaldehydes were synthesized as useful multisubstituted dienophiles. The Diels–Alder reaction of these dienophiles catalyzed by organoammonium salts provides an efficient route to structurally complicated chiral building blocks that contain a quaternary carbon atom substituted with an oxygen- or nitrogen-containing moiety.

■Inside Cover

▼IBS-Catalyzed Regioselective Oxidation of Phenols to 1,2-Quinones with Oxone

Muhammet Uyanik

Tatsuya Mutsuga

Kazuaki Ishihara*

Molecules 2012, 17(7), 8604-8616.

(the Special Issue: Hypervalent Compounds) 

▷DOI:10.3390/molecules1707860

We have developed the first example of hypervalent iodine(V)-catalyzed regioselective oxidation of phenols to o-quinones. Various phenols could be oxidized to the corresponding o-quinones in good to excellent yields using catalytic amounts of sodium salts of 2-iodobenzenesulfonic acids (pre-IBSes) and stoichiometric amounts of Oxone as a co-oxidant under mild conditions. The reaction rate of IBS-catalyzed oxidation under nonaqueous conditions was further accelerated in the presence of an inorganic base such as potassium carbonate (K2CO3), a phase transfer catalyst such as tetrabutylammonium hydrogen sulfate (nBu4NHSO4), and a dehydrating agent such as anhydrous sodium sulfate (Na2SO4).

▼N,N-Diarylammonium Pyrosulfate as a Highly Effective Reverse Micelle-Type Catalyst for Hydrolysis of Esters

Yoshiki Koshikari

Akira Sakakura

Kazuaki Ishihara*

Org. Lett. 2012, 14(12), 3194-3197. 

▷DOI: 10.1021/ol301290c

Reverse micelle-type N,N-diarylammonium pyrosulfate (3-5 mol %) efficiently catalyzes the hydrolysis of esters (up to 100 mmol scale) under organic solvent-free conditions. The present method is successfully applied to the hydrolysis of various esters without the decomposition of the base-sensitive moieties and without any loss of optical purity for alpha-heterosubstituted carboxylic acids.

▼Enantioselective Diels-Alder Reaction of alpha-(Acylthio)acroleins: A New Entry to Sulfur-Containing Chiral Quaternary Carbons

Akira Sakakura

Hiroki Yamada

Kazuaki Ishihara*

Org. Lett. 2012, 14(12), 2972-2975.

▷DOI: 10.1021/ol300921f

A catalytic and enantioselective Diels-Alder reaction of alpha-(carbamoylthio)acroleins induced by an organoammonium salt of chiral triamine is described. alpha(Carbamoylthio)acroleins are designed and synthesized as new sulfur-containing dienophiles for the first time. The Diels-Alder reaction affords chiral tertiary thiol precursors with up to 91% ee. 

▼Enantioselective direct aminalization with primary carboxamides catalyzed by chiral ammonium 1,1'-binaphthyl-2,2'-disulfonates 

Manabu Hatano

Takuya Ozaki

Yoshihiro Sugiura

Kazuaki Ishihara*

Chem. Commun. 2012, 48, 4986-4988.

▷DOI: 10.1039/C2CC31530K

A highly effective catalytic enantioselective direct aminal synthesis was developed. Chiral ammonium 1,1'-binaphthyl-2,2'-disulfonates, which were prepared in situ from (R)-BINSA and achiral amines, promoted the enantioselective addition of primary amides to aromatic aldimines.  

▼Conformationally Flexible Chiral Supramolecular Catalysts for Enantioselective Diels-Alder Reactions with Anomalous Endo/Exo Selectivities 

Manabu Hatano

Kazuaki Ishihara*

Chem. Commun. 2012, 48(36), 4273-4283.

▷DOI: 10.1039/C2CC00046F

The potential of supramolecular catalysts to realize anomalous regio- and/or stereoselectivity in organic synthesis is highly attractive. To date, there have been a few examples of non-polymeric and non-covalent chiral supramolecular catalysts that induce practical enantioselectivity. In this regard, a metal-organic framework (MOF) may be one of the most important techniques for constructing conformationally rigid supramolecular catalysts. However, it is not easy to use the MOF technique to fine-tune a much more precise cage in catalysts for anomalous purposes. To establish high catalytic activity with anomalous regio- and/or stereoselectivity, in principle, an artificial cage should be conformationally flexible, like an active pocket in an enzyme with an induced-fit function. In this feature article, we focus on the anomalous endo/exo-selective Diels-Alder reaction, and overview the development of the successive catalysts including our recent highly active, conformationally flexible, and chiral supramolecular catalysts. The evolution from ‘ready-made’ single-molecule catalysts to ‘tailor-made’ supramolecular catalysts could offer not only high enantioselectivity but also high anomalous endo/exo-selectivities due to substrate-specific characteristics, as with enzymes. 

▼Hydrophobic N,N-Diarylammonium Pyrosulfates as Dehydrative Condensation Catalysts under Aqueous Conditions

Akira Sakakura

Yoshiki Koshikari

Matsujiro Akakura

Kazuaki Ishihara*

Org. Lett. 2012, 14(1), 30-33.

▷DOI: 10.1021/ol2027366

Oil-soluble N,N-diarylammonium pyrosulfates as nonsurfactant-type catalysts for the dehydrative ester condensation under aqueous conditions are described. Preheat treatment of dibasic sulfuric acid with bulky N,N-diarylamines generates water-tolerant salts of pyrosulfuric acid as active catalyst species. The present catalysts in water can also widely be applied to unusual selective esterifications and dehydrative glycosylation.

▼2-Iodoxy-5-Methylbenzenesulfonic Acid-Catalyzed Selective Oxidation of 4-Bromobenzyl Alcohol to 4-Bromobenzaldehyde or 4-Bromobenzoic Acid with Oxone

Muhammet Uyanik

Kazuaki Ishihara*

Org. Synth. 2012, 89, 105-114.

▷http://www.orgsyn.org/

▼Catalysis with In Situ-Generated (Hypo)iodite Ions for Oxidative Coupling Reactions

Muhammet Uyanik

Kazuaki Ishihara*

ChemCatChem 2012, 4(2), 177-185.

(Article first published online: 23 DEC 2011)

▷  DOI: 10.1002/cctc.201100352

Hyping up the iodines: The discovery and development of oxidative coupling reactions catalyzed by inorganic iodine species (i.e., hypoiodite or iodite), which are generated in-situ from an iodide ion and hydrogen peroxide or tert-butyl hydroperoxide as an environmentally benign oxidant is highlighted.