Catalytic Transformations of Alkynes into either α-Alkoxy or α-Aryl Enolates: Mannich Reactions by Cooperative Catalysis and Evidence for Nucleophile-Directed Chemoselectivity
作者:Rajkumar Lalji Sahani、Manoj D. Patil、Sachin Bhausaheb Wagh、Rai-Shung Liu
DOI:10.1002/anie.201806883
日期:2018.11.5
The catalytic formation of gold enolatesfrom alkynes, nitrones, and nucleophiles is described, and their Mannich reactions result in nucleophile‐directed chemoselectivity through cooperative catalysis. For 1‐alkyn‐4‐ols and 2‐ethynylphenols, their gold‐catalyzed nitrone oxidations afforded N‐containing dihydrofuran‐3(2H)‐ones with syn selectivity. The mechanism involves the Mannich reactions of gold
Chiral phosphine-catalyzed tunable cycloaddition reactions of allenoates with benzofuranone-derived olefins for a highly regio-, diastereo- and enantioselective synthesis of spiro-benzofuranones
作者:De Wang、Guo-Peng Wang、Yao-Liang Sun、Shou-Fei Zhu、Yin Wei、Qi-Lin Zhou、Min Shi
DOI:10.1039/c5sc03135d
日期:——
The first regioselective catalytic asymmetric [3 + 2] cycloaddition of benzofuranone-derived olefins with allenoates and substituted allenoates has been developed in the presence of (R)-SITCP.
Synthesis of New Spirocyclopropane and Oxadiazole Products
作者:Amel Haouas、Naoufel Ben Hamadi[]、Moncef Msaddek
DOI:10.1002/jhet.2249
日期:2015.11
In explorations of synthesis and chemistry of spiroheterocycles, we found that the reaction of 2‐diazopropane with arylidene‐benzofuran‐2(3H)‐one and arylidene‐benzofuran‐3(2H)‐one derivatives generated the spirocyclopropaneproducts. In addition to the expected cycloadducts, an unexpected oxadiazole was formed in some cases. The structures of the obtained adducts have been assigned by means of spectroscopic
A Highly Efficient Chirality Switchable Synthesis of Dihydropyran-Fused Benzofurans by Fine-Tuning the Phenolic Proton of β-Isocupreidine (β-ICD) Catalyst with Methyl
A highlyenantioselective β‐isocupreidine (β‐ICD) catalyzed synthesis of dihydropyran‐fused benzofurans through [4+2] cycloaddition of allenoates and benzofuranone alkenes was developed. Switchable chirality inversion of cycloaddition products was achieved by replacing the phenolic proton of the catalyst with a methyl, demonstrating an amazing effect of minimal structural variation on inverting enantioselectivity
3-Arylidenebenzofuran-2(3H)-ones are obtained by condensation of aldehydes Ar1CHO with benzofuran-2(3H)-one. A mixture of stereoisomers (Z) and (E) was isolated. The reaction of diarylnitrilimines with the Z+E mixture or with each stereoisomer leads regio- and stereoselectively to cycloadducts which give, after acidic treatment, the same 5,6-diaryl-4-(o-hydroxyphenyl)pyridazin-3(2H)-one 6, irrespective of the double bond geometry of the starting olefin.