Transition‐Metal‐Promoted Direct C−H Cyanoalkylation and Cyanoalkoxylation of Internal Alkenes
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Radical C−C Bond Cleavage of Cycloketone Oxime Esters
作者:Jiang Lou、Yuan He、Yunlong Li、Zhengkun Yu
DOI:10.1002/adsc.201900402
日期:2019.8.21
d alkyl‐Heck‐type cross‐coupling of olefinic C−Hbonds has been a challenge in the C−H activation area. Herein, we report FeCl3‐promoted efficient direct C−Hcyanoalkylation of internal alkenes, that is, ketene dithioacetals, with cycloketone oxime esters via radical C−C bond cleavage under the redox‐neutral conditions. With CuCl2 as the catalyst under a dioxygen atmosphere direct C−H cyanoalkoxylation
Directing-Group-Based Strategy Enabling Intermolecular Heck-Type Reaction of Cycloketone Oxime Esters and Unactivated Alkenes
作者:Yi Deng、Chunyang Zhao、Yu Zhou、Hongwei Wang、Xuexiang Li、Gui-Juan Cheng、Junkai Fu
DOI:10.1021/acs.orglett.0c00963
日期:2020.5.1
A new type of coupling between unactivated olefins and nonstabilized alkyl radicals was achieved, which enabled the first intermolecularHeck-typereaction of cycloketone oxime esters and unactivated alkenes. This directing-group-based strategy was compatible with various unactivated alkenes and cyclobutanone-, cyclopentanone-, and cyclohexanone-derived oxime esters. Density functional theory calculations
Unexpected Formation of Optically Active 4-Substituted 5-Hydroxy-γ-lactams by Organocatalyzed Reaction of 3-Substituted Cyclobutanones with Nitrosobenzene
An organocatalyzed enantioselective desymmetrization reaction for converting 3-substituted cyclobutanones into 4-substituted 5-hydroxy-γ-lactams is presented. This involves a ring-expanding O-nitroso aldol-cyclization domino sequence. This synthetic protocol provides access to five-membered ring systems in good yields with the generation of two new stereogenic centers.
A new procedure for the desymmetrization of prochiral 3-substituted cyclobutanones has been established through organocatalyzed Michaeladdition to nitroalkenes. The approach provides enantiomerically enriched 2-alkyl-3-aryl(alkyl) cyclobutanones with three contiguous stereogenic centers. The optimum conditions were determined by screening of catalyst and reaction conditions and a transition-state
The reaction between configurably stable α-lithiated oxiranes and 3-substituted cyclobutanones allows obtaining enantiomerically enriched cyclobutanols (er > 98 : 2). These adducts, subjected to base-mediated Payne rearrangement, lead to the synthesis of a new class of oxaspirohexanes, useful precursors of 2,4-disubstituted cyclopentanones.