Stereoselective Synthesis of Highly Functionalized Nitrocyclopropanes through the Organocatalyic Michael‐Addition‐Initiated Cyclization of Bromonitromethane and β,γ‐Unsaturated α‐Ketoesters
A highly diastereo‐ and enantioselective cyclopropanation of β,γ‐unsaturated α‐ketoesters with bromonitromethane has been successfully developed through a domino Michael‐addition/intramolecular‐alkylation strategy. Acceptable yields (up to 89 %) and enantioselectivities (up to 96 % ee) have been obtained.
Diastereodivergent Catalysis Using Modularly Designed Organocatalysts: Synthesis of both<i>cis</i>- and<i>trans</i>-Fused Pyrano[2,3-<i>b</i>]pyrans
作者:Huicai Huang、Swapna Konda、John C.-G. Zhao
DOI:10.1002/anie.201510134
日期:2016.2.5
4a,8a‐tetrahydro‐2H,5H‐pyrano[2,3‐b]pyran‐7‐carboxylates have been obtained in high diastereoselectivities and enantioselectivities from the same starting materials using a tandem inverse‐electron‐demand hetero‐Diels–Alder/oxa‐Michael reaction catalyzed by modularly designed organocatalysts (MDOs). Diastereodivergence was achieved in these reactions through the direct control of the stereochemistry
F<sup>–</sup>-Free Deoxyhydrotrifluoromethylation of α-Keto Esters with Ph<sub>3</sub>P<sup>+</sup>CF<sub>2</sub>CO<sub>2</sub><sup>–</sup>: Synthesis of α–CF<sub>3</sub>-Substituted Esters
作者:Ying Zheng、Yimin Jia、Yuan Yuan、Zhong-Xing Jiang、Zhigang Yang
DOI:10.1021/acs.joc.0c01518
日期:2020.8.21
direct deoxyhydrotrifluoromethylation of α-keto esters with a difluoromethylating reagent has been achieved, in which the employment of water can promote the dissociation of the CF2 group to form a CF3 moiety, which provides the successful transformation. The current protocol demonstrates one of the most practical approaches to generate α-trifluoromethyl esters with a broad substrate scope and high functional
Unexpected Cascade Reactions of
<i>Ortho</i>
‐Hydroxyenaminones and β,γ‐Unsaturated α‐Ketoesters to Access Hydrogenated Benzoxazolepolycycles and Pyrrole−Phenol Atropisomers
作者:Xuguan Bai、Lele Wang、Ziying Zhang、Kuan Zhang、Zhanwei Bu、Yufeng Wu、Wenjing Zhang、Qilin Wang
DOI:10.1002/adsc.201900950
日期:2019.11.5
BF3 ⋅ OEt2‐catalyzed Michael addition/cyclization/dehydration sequence of ortho‐hydroxyenaminones with aromatic or aliphatic aldehyde‐derived β,γ‐unsaturated α‐ketoesters has been achieved to afford a wide range of fused hydrogenated benzoxazole polycycles in 67–95% yields in a highlydiastereoselective manner. When isatin‐derived β,γ‐unsaturated α‐ketoesters were employed as substrates, completely different reactivities
The asymmetric construction of quaternarycarboncentersviacross-aldolreactions of ketones with β,γ-unsaturated keto esters catalyzed by 4-(tert-butyldiphenylsilyloxy)-pyrrolidine-2-carboxylic acid in water is described. The adducts bearing two adjacent chiral centers were obtained in high yields, mostly up to 99% ee, and with high diastereoselectivities. The corresponding polyfunctional products