The facile construction of chiral quaternaryα-alkenylated pyrrolidinones is a long-term challenge in organic synthesis.The asymmetric difunctionalization of 1,3-dienes represents the most compelling tool for assembli...The facile construction of chiral quaternaryα-alkenylated pyrrolidinones is a long-term challenge in organic synthesis.The asymmetric difunctionalization of 1,3-dienes represents the most compelling tool for assembling alkenylated compounds by regioselective 1,2-or 1,4-difunctionalization.Nevertheless,the manipulation of unactivated 1,3-dienes to forge the quarternary stereogenic center still remains largely underdeveloped.Herein,we disclose a nickelcatalyzed asymmetric 1,4-arylcarbamoylation of unactivated 1,3-dienes tethered on carbamoyl fluoride with readily available arylboronic acids,providing rapid access to the enantioenrichedα-alkenylated pyrrolidinones bearing the quaternary stereogenic center in high yields with broad functional group tolerance.Moreover,this chiral ligand-controlled asymmetric transformation overcomes the intrinsic substrate control with a preexisting chiral center.展开更多
1,3-Diene architectures are not only widely present in natural products, pharmaceuticals, and functional organic materials but also serve as versatile building blocks to furnish important functionalized molecules in s...1,3-Diene architectures are not only widely present in natural products, pharmaceuticals, and functional organic materials but also serve as versatile building blocks to furnish important functionalized molecules in synthetic chemistry due to conjugated repeating C=C units. Accordingly, various strategies to access substituted 1,3-dienes in a stereoselective manner have been developed. However, chemo-, regio-and stereoselective synthesis of highly substituted 1,3-dienes still remains elusive and challenging. Readily available propargylic esters have emerged as an appealing class of synthetic intermediates for accessing functionalized 1,3-dienes, especially challenging tri-or tetrasubstituted variants, via transition-metal catalysis, including electrophilic metal and redox neutral catalysis. This review, for the first time, systematically highlights recent advances in transitionmetal catalyzed synthesis of substituted 1,3-dienes from propargylic esters, discusses the mechanisms and synthetic utilities, and gives the remaining challenges and potential opportunities in this field.展开更多
Dienols are important structural motifs in organic molecules,but most of the traditional synthetic methods required multistep prefunctionalization of substrates,leading to stoichiometric waste and low atom economy.Her...Dienols are important structural motifs in organic molecules,but most of the traditional synthetic methods required multistep prefunctionalization of substrates,leading to stoichiometric waste and low atom economy.Herein,we report a redox-neutral coupling of simple 1,3-dienes and aldehydes via nickel and Brønsted acid dual catalysis,providing a highly atom-economical and by-product-free route to various dienols with up to 94%yield and up to 50∶1 EE/EZ ratio.The use of 2-isopropoxyphenol as a Brønsted acid co-catalyst was critical to the reactivity and selectivity.展开更多
Two new sterols, 3 beta, 7 alpha, 16 beta -trihydroxy-stigmast-5,22-diene (1), 3 beta, 7 alpha, 16 beta -trihydroxy-stigmast-5-ene (2), were isolated together with six known compounds, ergosta-5, 24(28)-dien-3 beta, 7...Two new sterols, 3 beta, 7 alpha, 16 beta -trihydroxy-stigmast-5,22-diene (1), 3 beta, 7 alpha, 16 beta -trihydroxy-stigmast-5-ene (2), were isolated together with six known compounds, ergosta-5, 24(28)-dien-3 beta, 7 alpha -diol (3), ergosta-5,24(28)-dien-3 beta, 7 beta, 16 beta -triol (4), beta -amyrone (5), beta -amyrin (6), 11 alpha, 12 alpha -epoxy-14-taraxeren-3-one (7), and 6-guaiene-4 alpha, 10 alpha -diol (8) from the EtOH extract of the bark of Amoora yunnanensis (H. L. Li) C. Y. Wu. Their structures were deduced on the basis of spectral data.展开更多
The reaction mechanisms of diene polymerization with homogeneous rare earth catalyst are studied by means of the spectra of ~1H-NMR, one-and two-dimensions ^(13)C-NMR. Based on the data of above NMR spectra, it is pro...The reaction mechanisms of diene polymerization with homogeneous rare earth catalyst are studied by means of the spectra of ~1H-NMR, one-and two-dimensions ^(13)C-NMR. Based on the data of above NMR spectra, it is proposed that the polymerization reaction proceeds according to the following mechanism: η~4-diene (cis-trans-)and η~3-allyl (syn-anti-).展开更多
Two new sterols. 3 beta,7 alpha, 16 beta-trihydroxy-stigmast-5,22-diene 1,3 beta,7 alpha,16 beta-trihydroxy-stigmast-5-ene 2. were isolated together with two known ergosterols, ergosta-5,24(28)-diene-3 beta.7 alpha-di...Two new sterols. 3 beta,7 alpha, 16 beta-trihydroxy-stigmast-5,22-diene 1,3 beta,7 alpha,16 beta-trihydroxy-stigmast-5-ene 2. were isolated together with two known ergosterols, ergosta-5,24(28)-diene-3 beta.7 alpha-diol, ergosta-5,24(28)-diene-3 beta,7 beta,16 beta-triol from the bark of Amoora yunnanensis (H. L. Li) C. Y. Wu. Their structures were deduced on the basis of spectral data.展开更多
基金supported by National Natural Science Foundation of China(grant no.22171079)the Natural Science Foundation of Shanghai(grant no.21ZR1480400)+3 种基金the Shanghai Rising-Star Program(grant no.20QA1402300)the Shanghai Municipal Science and Technology Major Project(grant no.2018SHZDZX03)the Program of Introducing Talents of Discipline to Universities(grant no.B16017)the Fundamental Research Funds for the Central Universities and the China Postdoctoral Science Foundation(grant no.2021M701197).
文摘The facile construction of chiral quaternaryα-alkenylated pyrrolidinones is a long-term challenge in organic synthesis.The asymmetric difunctionalization of 1,3-dienes represents the most compelling tool for assembling alkenylated compounds by regioselective 1,2-or 1,4-difunctionalization.Nevertheless,the manipulation of unactivated 1,3-dienes to forge the quarternary stereogenic center still remains largely underdeveloped.Herein,we disclose a nickelcatalyzed asymmetric 1,4-arylcarbamoylation of unactivated 1,3-dienes tethered on carbamoyl fluoride with readily available arylboronic acids,providing rapid access to the enantioenrichedα-alkenylated pyrrolidinones bearing the quaternary stereogenic center in high yields with broad functional group tolerance.Moreover,this chiral ligand-controlled asymmetric transformation overcomes the intrinsic substrate control with a preexisting chiral center.
基金supported by the National Natural Science Foundation of China (22071111)the Jiangsu Specially Appointed Professor Plan+1 种基金the Natural Science Foundation of Jiangsu Province(BK20201368, BK20220409)the Postgraduate Research&Practice Innovation Program of Jiangsu Province (KYCX23_1683)。
文摘1,3-Diene architectures are not only widely present in natural products, pharmaceuticals, and functional organic materials but also serve as versatile building blocks to furnish important functionalized molecules in synthetic chemistry due to conjugated repeating C=C units. Accordingly, various strategies to access substituted 1,3-dienes in a stereoselective manner have been developed. However, chemo-, regio-and stereoselective synthesis of highly substituted 1,3-dienes still remains elusive and challenging. Readily available propargylic esters have emerged as an appealing class of synthetic intermediates for accessing functionalized 1,3-dienes, especially challenging tri-or tetrasubstituted variants, via transition-metal catalysis, including electrophilic metal and redox neutral catalysis. This review, for the first time, systematically highlights recent advances in transitionmetal catalyzed synthesis of substituted 1,3-dienes from propargylic esters, discusses the mechanisms and synthetic utilities, and gives the remaining challenges and potential opportunities in this field.
基金the National Natural Science Foundation of China(21672107 and 21871145)the Fundamental Research Funds for the Central Universities(Nankai University,63191601)the Tianjin Applied Basic Research Project and Cutting-Edge Technology Research Plan(19JCZDJC37900)for financial support.
文摘Dienols are important structural motifs in organic molecules,but most of the traditional synthetic methods required multistep prefunctionalization of substrates,leading to stoichiometric waste and low atom economy.Herein,we report a redox-neutral coupling of simple 1,3-dienes and aldehydes via nickel and Brønsted acid dual catalysis,providing a highly atom-economical and by-product-free route to various dienols with up to 94%yield and up to 50∶1 EE/EZ ratio.The use of 2-isopropoxyphenol as a Brønsted acid co-catalyst was critical to the reactivity and selectivity.
文摘Two new sterols, 3 beta, 7 alpha, 16 beta -trihydroxy-stigmast-5,22-diene (1), 3 beta, 7 alpha, 16 beta -trihydroxy-stigmast-5-ene (2), were isolated together with six known compounds, ergosta-5, 24(28)-dien-3 beta, 7 alpha -diol (3), ergosta-5,24(28)-dien-3 beta, 7 beta, 16 beta -triol (4), beta -amyrone (5), beta -amyrin (6), 11 alpha, 12 alpha -epoxy-14-taraxeren-3-one (7), and 6-guaiene-4 alpha, 10 alpha -diol (8) from the EtOH extract of the bark of Amoora yunnanensis (H. L. Li) C. Y. Wu. Their structures were deduced on the basis of spectral data.
基金The Project is supported by "Laboratory of Physics & Chemistry, Academia Sinica" and "National Natural Science Foundation of China"
文摘The reaction mechanisms of diene polymerization with homogeneous rare earth catalyst are studied by means of the spectra of ~1H-NMR, one-and two-dimensions ^(13)C-NMR. Based on the data of above NMR spectra, it is proposed that the polymerization reaction proceeds according to the following mechanism: η~4-diene (cis-trans-)and η~3-allyl (syn-anti-).
文摘Two new sterols. 3 beta,7 alpha, 16 beta-trihydroxy-stigmast-5,22-diene 1,3 beta,7 alpha,16 beta-trihydroxy-stigmast-5-ene 2. were isolated together with two known ergosterols, ergosta-5,24(28)-diene-3 beta.7 alpha-diol, ergosta-5,24(28)-diene-3 beta,7 beta,16 beta-triol from the bark of Amoora yunnanensis (H. L. Li) C. Y. Wu. Their structures were deduced on the basis of spectral data.
