Cooperativity within the catalyst: alkoxyamide as a catalyst for bromocyclization and bromination of (hetero)aromatics
作者:Haripriyo Mondal、Md Raja Sk、Modhu Sudan Maji
DOI:10.1039/d0cc04673f
日期:——
Alkoxyamide has been reported as a catalyst for the activation of N-bromosuccinimide to perform bromocyclization and bromination of a wide range of substrates in a lipophilic solvent, where adequate suppression of the background reactions was observed. The key feature of the active site is the alkoxy group attached to the sulfonamide moiety, which facilitates the acceptance as well as the delivery
A Catalyst-Controlled Enantiodivergent Bromolactonization
作者:Yuk-Cheung Chan、Xinyan Wang、Ying-Pong Lam、Jonathan Wong、Ying-Lung Steve Tse、Ying-Yeung Yeung
DOI:10.1021/jacs.1c05680
日期:2021.8.18
enantiodivergent bromolactonization of olefinicacids has been developed. Quinine-derived amino-amides bearing the same chiral core but different achiral aryl substituents were used as the catalysts. Switching the methoxy substituent in the aryl amide system from meta- to ortho-position results in a complete switch in asymmetric induction to afford the desired lactone in good enantioselectivity and yield
ZnI<sub>2</sub>/Zn(OTf)<sub>2</sub>-TsOH: a versatile combined-acid system for catalytic intramolecular hydrofunctionalization and polyene cyclization
作者:Ting-Hung Chou、Bo-Hung Yu、Rong-Jie Chein
DOI:10.1039/c9cc07242j
日期:——
combined-acid system using a zinc(II) salt [ZnI2 or Zn(OTf)2] and p-toluene sulfonic acid (TsOH) was investigated for catalytic cationic cyclizations, including intramolecular hydrocarboxylation, hydroalkoxylation, hydroamination, hydroamidation, hydroarylation and polyenecyclizations. This reaction provides easy access to five- and six-membered O- and N-containing saturated heterocyclic compounds, tetrahydronaphthalene
The apple never falls far from the tree: S‐alkylthiocarbamate 1 (see scheme, NBP=N‐bromophthalimide) was prepared in high yield through a synthetic sequence involving a Newman–Kwart rearrangement of the corresponding O‐alkylthiocarbamates. Compound 1 was used to catalyze bromolactonization, thus providing enantioenriched δ‐lactones in excellent yield and enantioselectivity.
Electrochemical oxidative bromolactonization of unsaturated carboxylic acids with sodium bromide: Synthesis of bromomethylated γ-lactones
作者:Rabin Kim、Jeauk Ha、Jiwon Woo、Dae Young Kim
DOI:10.1016/j.tetlet.2021.153567
日期:2022.1
Electrochemical oxidative bromination and cyclization sequences of unsaturated carboxylic acids were developed in this study. This approach is environmentally-friendly, using bromide anion as bromine radical precursor without external oxidizing reagents. The electrochemical protocol offers a facile way to prepare bromomethylated γ-lactones derivatives in moderate to high yields.