Direct Synthesis of 4-Fluoroisoxazoles through Gold-Catalyzed Cascade Cyclization–Fluorination of 2-Alkynone O-Methyl Oximes
摘要:
A tandem protocol for the synthesis of fluorinated isoxazoles has been developed via catalytic intramolecular cyclizations of 2-alkynone O-methyl mimes and ensuing fluorination. The reactions proceed smoothly at room temperature in the presence of 5 mol % of (IPr)AuCl, 5 mol % of AgOTs, 2.5 equiv of Selectfluor, and 2 equiv of NaHCO3. This process features an efficient one-pot cascade route to fluoroisoxazoles with high yields and high selectivity under mild reaction conditions.
Direct Synthesis of 4-Fluoroisoxazoles through Gold-Catalyzed Cascade Cyclization–Fluorination of 2-Alkynone O-Methyl Oximes
摘要:
A tandem protocol for the synthesis of fluorinated isoxazoles has been developed via catalytic intramolecular cyclizations of 2-alkynone O-methyl mimes and ensuing fluorination. The reactions proceed smoothly at room temperature in the presence of 5 mol % of (IPr)AuCl, 5 mol % of AgOTs, 2.5 equiv of Selectfluor, and 2 equiv of NaHCO3. This process features an efficient one-pot cascade route to fluoroisoxazoles with high yields and high selectivity under mild reaction conditions.
Catalyst‐Controlled Dual Reactivity of Sulfonimidamides: Synthesis of Propargylamines and
<i>N</i>
‐Propargyl Sulfonimidamides
作者:Irfana Jesin C. P.、Ganesh Chandra Nandi
DOI:10.1002/chem.201805000
日期:2019.1.14
amines and nucleophiles depending on the reaction conditions to access propargylamines and N‐propargyl SIAs, respectively. The amine part of SIAs has been cleaved in an InCl3‐catalyzed three‐component A3 coupling reaction with aldehyde and acetylene to yield propargylamine. Moreover, N‐propargyl SIAs were obtained via the direct‐imination of propargylalcohols in the presence of BF3⋅OEt2.
Boron Trihalide Mediated Substitution of Hydroxyl Groups with Alkenyl, Alkynyl, and Allyl Moieties
作者:George Kabalka、Scott Borella、Min-Liang Yao
DOI:10.1055/s-2007-990816
日期:2008.1
The coupling of alcohols with alkenyl- and alkynylboron dihalides with high olefin stereoselectivity is described. The reaction provides a facile route to internal acetylenes. Notably, the allylation of propargylic alcohols mediated by borontrichloride proceeds smoothly at room temperature and gives excellent regioselectivity.
In Situ Generation of Allenes and their Application to One‐Pot Assembly of Functionalized Fluoreno[3,2‐
<i>b</i>
]furans by Calcium‐Catalyzed, Regioselective, 3‐Component Reactions
作者:Srinivasarao Yaragorla、Pallava Rajesh
DOI:10.1002/ejoc.202001310
日期:2020.12.13
A novel synthetic methodology for the synthesis of tetra‐annulated fluorenofurans and fluorenopyrans using calcium(II)‐catalyzed one‐pot, three‐component reaction is developed from propargyl alcohols and 1,3‐dicarbonyls through the formation of tetra‐substituted allenes as the key intermediates.
<i>p</i>-TSA/Base-Promoted Propargylation/Cyclization of β-Ketothioamides for the Regioselective Synthesis of Highly Substituted (Hydro)thiophenes
作者:Ganesh Chandra Nandi、Maya Shankar Singh
DOI:10.1021/acs.joc.6b00342
日期:2016.7.15
achieved at room temperature. In addition, the reaction also provided thiazole rings as byproducts. Furthermore, the propargylated thioamides undergo intramolecular 1,5-cyclization to afford fully substituted (hydro)thiophenes in the presence of base. Notably, the approach is pot, atom, and step economical (PASE).
Catalyst-Controlled Straightforward Synthesis of Highly Substituted Pyrroles/Furans via Propargylation/Cycloisomerization of α-Oxoketene-N,S-acetals
作者:Ganesh Chandra Nandi、Soumini K
DOI:10.1021/acs.joc.6b02367
日期:2016.12.2
A facile and efficient InCl3 catalyzed one-pot synthesis of highly substituted pyrroles has been developed via a tandem propargylation/cycloisomerization reaction of α-oxoketene-N,S-acetals with propargyl alcohols. Notably, in the presence of Bronsted acid p-TSA·H2O, the reaction afforded the hydrolyzed product propargylated-1,3-dicarbonyl compounds, which upon treatment with Cs2CO3 underwent regioselective
通过α-氧杂环丁烯-N,S-乙缩醛与炔丙醇的串联炔丙基化/环异构化反应,已经开发出一种简便高效的InCl 3催化一锅合成高取代的吡咯。值得注意的是,在布朗斯台德酸对-TSA·H 2 O的存在下,反应提供了水解产物炔丙基化的1,3-二羰基化合物,其在用Cs 2 CO 3处理后进行了区域选择性的分子内环化,从而提供了四取代的呋喃衍生物。