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Reaction-based mechanistic investigations were performed for the hetero-Diels-Alder (hDA) reactions of enones with isatins that were catalyzed by an amine-based catalyst system composed of three molecules (an amine, an acid, and a thiourea). The results indicated that the hDA product obtained from the reaction between hept-3-en-2-one and isatin using the amine-based catalyst system was generated via a kinetically controlled [4+2] cycloaddition reaction of the in situ-generated enamine of the enone as the diene and isatin as the dienophile. The amine of the three-component catalyst system was essential for the catalysis and stereocontrol, but the other components of the catalyst system also played important roles. Based on the results, plausible transition states are discussed, and the system was further improved by altering the loadings of the catalyst components for faster reactions with high stereoselectivities. The three-component catalyst systems are flexible and can be tuned to obtain better results. [ABSTRACT FROM AUTHOR]

An efficient synthesis of the 2,3-disubstituted piperidines (+)-L-733,060 and (2S,3S)-3-hydroxypipecolic acid (⩾99% ee) in high optical purity from commercially available starting materials is described. The strategy involves a cobalt-catalyzed hydrolytic kinetic resolution of a racemic azido epoxide with two stereocenters and an intramolecular reductive cyclization as key reactions [ABSTRACT FROM AUTHOR]

Abstract: A new milder protocol for aziridination of a variety of olefins has been described. The process employs catalytic amount of sodium metaperiodate (NaIO4) as an oxidant and LiBr and chloramine-T as the bromine and nitrogen sources, respectively. Interestingly, the formation of aziridine products in all the cases studied takes place presumably through a process of 1,2-aminobromination of alkenes. [Copyright &y& Elsevier]

Abstract: The NaIO4–KI–NaN3 combination has been found to be an efficient, reliable, and inexpensive reagent system for mono- and 1,2-difunctionalization of hydrocarbons via C–H bond activation to afford vicinal azido- and acetoxy iodinations of cyclic hydrocarbons. [Copyright &y& Elsevier]

Reaction‐based mechanistic investigations were performed for the asymmetric hetero‐Diels–Alder reactions of enones with isatins catalyzed by an amine‐based three‐component catalyst system. The reaction route was likely a kinetically controlled [4+2] cycloaddition reaction of the in situ‐generated enamine of the enone as the diene and isatin as the dienophile. All three components of the catalyst system played important roles for the catalysis and the stereocontrol. More information can be found in the Full Paper by F. Tanaka and co‐workers on page 153 in Issue 1, 2016 (DOI: 10.1002/ajoc.201500412). [ABSTRACT FROM AUTHOR]

The decalin structure is found in bioactive molecules. We have developed catalytic enantioselective formal (4+2) cycloaddition reactions via aldol-aldol cascade reactions between pyruvate-derived diketoester derivatives and cyclohexane-1,3-dione derivatives that afford highly functionalized decalin derivatives. The reactions were performed using a quinidine-derived catalyst under mild conditions. Decalin derivatives bearing up to six chiral carbon centers including tetrasubstituted carbon centers were synthesized with high diastereo- and enantioselectivities. Five to six stereogenic centers were generated from achiral molecules with the formation of two C-C bonds in a single transformation resulting in the formation of the decalin system., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)