Metal-Free, Aerobic Dioxygenation of Alkenes Using Hydroxamic Acids
作者:Valerie A. Schmidt、Erik J. Alexanian
DOI:10.1002/anie.201000843
日期:2010.6.14
One dioxygenation please, hold the metal: In the presence of either oxygen or air as the sole oxidant and external oxygen atom source, a variety of unsaturated hydroxamicacids afford cyclic hydroxamates that are readily converted into 1,2‐diols, with the potential for high levels of reaction stereocontrol.
A method for aerobic alcoholoxidation catalysed by Fe(NO3 )3 /2,2'-bipyridine/TEMPO has allowed highlyselective conversion of primaryalcohols into either aldehydes or carboxylic acids in one-step. The oxidation of primaryalcohols proceeded selectively to aldehydes, as TEMPO was present in the reaction. Nevertheless, the aldehydes were further oxidized into carboxylic acids as the reaction time
A highly regioselective nickel-based catalyst system for the isomerization/hydrocyanation of aliphatic internal olefins is described. This benign tandem reaction provides facile access to a wide variety of aliphatic nitriles in good yields with excellent regioselectivities. Thanks to Lewis acid-free conditions, the protocol features board functional groups tolerance, including secondary amine and unprotected
Enantio‐ and Diastereoselective, Lewis Base Catalyzed, Cascade Sulfenoacetalization of Alkenyl Aldehydes
作者:Anastassia Matviitsuk、Scott E. Denmark
DOI:10.1002/anie.201906535
日期:2019.9.2
catalytic, enantio-, and diastereoselective formation of sulfenyl acetals bearingmultiplestereogeniccenters is reported. Alkenyl aldehydes undergo a chiral thiiranium ion initiated cascade starting with intramolecular capture by a formyl group and termination by capture with HFIP solvent. This method provides a one-potsynthesis of dihydropyran and 1,3-disubstituted isochroman acetals in good to excellent
Enzymatic epoxidation represents a key biosynthetic transformation in the construction of polyether skeletons. A single flavin-containing monooxygenase, Lsd18, is involved in ionophore polyether lasalocid biosynthesis and participates in the enantioselective epoxidations of the diene precursor. Biotransformation studies utilizing structurally simplified monoolefin analogs with different substitution patterns revealed important structural requirements for the enantiofacial selectivity of Lsd18-catalyzed epoxidations. These results enabled us to propose a substrate binding model of Lsd18, which was applied to the biosynthesis of other polyethers.