The vinylogous aldol reaction: a valuable, yet understated carbon-carbon bond-forming maneuver.

C2-symmetric bis(oxazoline)−Cu(II) complexes 1 and 2 catalyze the inverse electron demand hetero Diels−Alder reaction of α,β-unsaturated carbonyl compounds (heterodiene) with electron-rich olefins (heterodienophile) in high diastereo- and enantioselectivity. α,β-Unsaturated acyl phosphonates and β,γ-unsaturated α-keto esters and amides are effective heterodienes, while enol ethers and sulfides function as heterodienophiles. A range of substitution patterns is possible on the heterodiene:  terminal alkyl, aryl, alkoxy, and thioether substituents are all tolerated. The enantioselective synthesis of dihydropyrans by this method has been shown to be straightforward:  cycloadditions may be conducted with as little as 0.2 mol % of the chiral catalyst and are readily run on multigram scale. The reactions exhibit a favorable temperature−enantioselectivity profile, with selectivities exceeding 90% even at room temperature. A simple reaction protocol that employs a solid air-stable catalyst, convenient reaction tem...

Enantioselective Synthesis of Dihydropyrans. Catalysis of Hetero Diels−Alder Reactions by Bis(oxazoline) Copper(II) Complexes

A review of techniques for the preparation of biological samples for mass-spectrometric measurements of hydrogen-2/hydrogen-1 and oxygen-18/oxygen-16 isotope ratios

Studies of solid base catalysis performed in our group are summarized. Strongly basic sites for most solid base catalysts are generated by removal of water and carbon dioxide by pretreatment at high temperatures from the surfaces. The nature of the surface basic sites varies with the severity of the pretreatment conditions. Rearrangement of surface and bulk atoms occurs, in addition to the removal of water and carbon dioxide, during the pretreatment. The optimum pretreatment temperature varies with the type of reaction. Characterization of basic sites by the indicator method, TPD of CO 2 , O exchange between adsorbed CO 2 and MgO surface, NMR of 133 Cs and 19 F are described. The catalytic behaviors of solid base catalysts are described for the following reactions; (I) double bond migration, (2) hydrogenation, (3) amination, (4) aldol addition, (5) nitroaldol reaction, (6) Michael addition, (7) conjugate addition of alcohol, (8) cyanoethylation, (9) transesterification of ethyl acetate and alcoholysis of propylene oxide, and (10) the Tishchenko reaction. The strength of basic sites relevant to different reactions is discussed based on the activity order among alkaline earth oxides, and the optimum pretreatment temperatures of MgO for different reactions. Reactions with hydrocarbons need strongly basic sites, whereas reactions with compounds containing functional groups proceed even on weakly basic sites. Finally, important issues to be investigated for the development of solid base catalysis are pointed out.

https://www.jstage.jst.go.jp/article/jpi/47/2/47_2_67/_pdf

固体塩基触媒: 塩基点の発現, キャラクタリゼーションおよび触媒作用

Stereospecific hydroxylation of long chain compounds by a species of Torulopsis.

Chemistry of methylnorbornyl cations. VI. The stereochemistry of vicinal hydride shift. Evidence for the nonclassical structure of 3-methyl-2-norbornyl cations

James H. Hammons

Papers

Chemistry of methylnorbornyl cations. VI. The stereochemistry of vicinal hydride shift. Evidence for the nonclassical structure of 3-methyl-2-norbornyl cations

The Synthesis of Three Monodeuterionorbornanes, and the Stereochemistry of Acid-Catalyzed Cleavage of Nortricyclene

Photochemistry of a triplet biradical. Cyclization, cleavage, and hydrogen shift in 2-isopropylidenecyclopentane-1,3-diyl

Chemistry of methylnorbornyl cations. V. Solvent capture and hydride shift in the 3-endo-methyl series

exo Vicinal Hydride Shift in the 3-endo-Methyl-2-norbornyl Cation1