Construction of Multi-Substituted Benzenes via NHC-Catalyzed Reactions of Carboxylic Esters
作者:Jichang Wu、Chengli Mou、Yonggui Robin Chi
DOI:10.1002/cjoc.201700773
日期:2018.4
A carbene‐catalyzed ester activation reaction for the synthesis of multi‐substituted benzenes is developed. Tetra‐substituted benzene compounds are efficiently synthesized through this methodology. Compared with aldehyde substrates used in previous reports, the ester substrates used here are much more readily available and inexpensive. In addition, the TEMPO oxidant used here is more inexpensive than
Me<sub>3</sub>SiCF<sub>2</sub>Br-Self-Assisted Domino Reaction: Catalytic Synthesis of α,α-Difluorocyclopentanones from Methylvinylketones
作者:Jian Chang、Cong Xu、Jie Gao、Fengyun Gao、Dongsheng Zhu、Mang Wang
DOI:10.1021/acs.orglett.7b00611
日期:2017.4.7
in the domino conversion of methylvinylketones into α,α-difluorinated cyclopentanones. Initiated by 5 mol % of nBu4NBr, the multistep reaction occurred in one pot under mild conditions via the in situ formation of silyl dienol ethers, difluorocyclopropanation, thermal vinylcyclopropane–cyclopentene rearrangement, and desilylation. The process takes advantage of the multitasking capability of Me3SiCF2Br
Condensation of carbonyl derivatives 2 with active methylene compounds 1 is efficiently achieved, within 3 to 15 minutes under microwave irradiation by a solvent free reaction in the presence of carefully adjusted amounts of piperidine leading to Knoevenagel products 3 in good to excellent yields.
Reaction of Corey Ylide with α,β-Unsaturated Ketones: Tuning of Chemoselectivity toward Dihydrofuran Synthesis
作者:Alexey O. Chagarovsky、Ekaterina M. Budynina、Olga A. Ivanova、Elena V. Villemson、Victor B. Rybakov、Igor V. Trushkov、Mikhail Ya. Melnikov
DOI:10.1021/ol500877c
日期:2014.6.6
A straightforward, efficient, and reliable approach to synthetically valuable 2,3-dihydrofurans via a reaction between Corey ylide and α,β-unsaturated ketones has been developed. The use of simple and widely spread starting materials as well as mild reaction conditions and scalability provide a broad scope of 2,3-dihydrofurans.
Efficient promiscuous Knoevenagel condensation catalyzed by papain confined in Cu<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub> nanoflowers
作者:Jianyun Yu、Xinxin Chen、Min Jiang、Anming Wang、Linlin Yang、Xiaolin Pei、Pengfei Zhang、Stephen Gang Wu
DOI:10.1039/c7ra12940h
日期:——
have been investigated for Knoevenagelcondensation reactions with hNFs as catalyst. At optimal conditions, product yield of the hNFs catalyzed reaction was 1.3 fold higher than that of the free enzyme with benzaldehyde and acetylacetone as substrates. A few aldehydes and methylene compounds have also been used to test the generality and scope of this new enzymatic promiscuity. To sum up, the obtained