As the cross-coupling needs of chemists continue to grow for accessing increasingly complex targets,radical-based transformations have become mainstay methodologies for the discovery of new reactivity under mild and w...As the cross-coupling needs of chemists continue to grow for accessing increasingly complex targets,radical-based transformations have become mainstay methodologies for the discovery of new reactivity under mild and wastelimiting conditions.En route to such methodological advancements,the observation of the 1,2-boron shift a novel radical rearrangement in its application has generated a new cross-coupling methodology to access products that were previously inaccessible or otherwise cumbersome to make.The origins of this radical rearrangement along with the synthetic applications to organic chemistry are highlighted.展开更多
A systematic calculation of the potential curves or surfaces for 1,2-shift has been realized by using MNDO or other models in MOPAC programs. By referring to the previous authors’ viewpoints, the 1,2-shift can be div...A systematic calculation of the potential curves or surfaces for 1,2-shift has been realized by using MNDO or other models in MOPAC programs. By referring to the previous authors’ viewpoints, the 1,2-shift can be divided into two categories. 1,2-electron-deficient shift is that the electronic configuration of the atom which accepts the migrating group is a cation or an electron-deficient atom, and 1,2-anion shift is the one that the accepted atom of the migration group is a negative ion. In terms of the experimental facts and the calculation of the potential surfaces, in electron-deficient shift such as Beckmann or Baeyer-Villiger rearrangement, the migration occurs through a transition complex formed between the 7i-bond and the cation or electron-deficient migrating group, but in anion shift such as Wittig or Stevens rearrangement, the electron pair in it-orbit excites at first to π* orbit, and then the migration occurs through the new formed complex between the anion migration group and the vacant展开更多
The mass spectrometric behaviour of four cis- and trans-1a, 3-disuhsdtuted-1,1-dichloro-4-formyl-1a,2,3,4-tetrahydro-1H-azirino[1, 2-a] [1, 5]benzodiazepines has been studied with the aid of mass-analysed ion kinetic ...The mass spectrometric behaviour of four cis- and trans-1a, 3-disuhsdtuted-1,1-dichloro-4-formyl-1a,2,3,4-tetrahydro-1H-azirino[1, 2-a] [1, 5]benzodiazepines has been studied with the aid of mass-analysed ion kinetic energy spectrometry and exact mass measurements under electron impact ionization. All compounds show a tendency to eliminate a chlorine atom from the aziridine ring, and then eliminate a neutral propene or styrene from the diazepine ring to yield azirino[1, 2b][1,3] benzimidazole ions. These azirino[1,2-a][1,5]benzodiazepines can also eliminate HCl, or Cl plus HCl simultaneously to undergo a ring enlargement rearrangement to yield 1,6-benzodiazocine ions, which further lose small molecular fragments, propyne or phenylacetylene, with rearrangement to give quinoxaline ions.展开更多
The semipinacol rearrangement is one of the classic yet useful synthetic tools in organic synthesis.However,semipinacol rearrangements involving heteroatom-migration are rare.Reported herein is a boryl-migratory semip...The semipinacol rearrangement is one of the classic yet useful synthetic tools in organic synthesis.However,semipinacol rearrangements involving heteroatom-migration are rare.Reported herein is a boryl-migratory semipinacol rearrangement of α-hydroxyallylboronates and α-hydroxypropargylboronates triggered by diverse halogen-,oxygen-,sulfur-and seleniumcontaining electrophiles.The protocol leads to a mild and facile access to organoborons bearing valuable functionalities.The σ(C-B)hyperconjugation is believed to be the key factor that leads to the observed exclusive chemoselectivity and enhanced reactivity.Synthetic utilities of the formed products were demonstrated.展开更多
文摘As the cross-coupling needs of chemists continue to grow for accessing increasingly complex targets,radical-based transformations have become mainstay methodologies for the discovery of new reactivity under mild and wastelimiting conditions.En route to such methodological advancements,the observation of the 1,2-boron shift a novel radical rearrangement in its application has generated a new cross-coupling methodology to access products that were previously inaccessible or otherwise cumbersome to make.The origins of this radical rearrangement along with the synthetic applications to organic chemistry are highlighted.
文摘A systematic calculation of the potential curves or surfaces for 1,2-shift has been realized by using MNDO or other models in MOPAC programs. By referring to the previous authors’ viewpoints, the 1,2-shift can be divided into two categories. 1,2-electron-deficient shift is that the electronic configuration of the atom which accepts the migrating group is a cation or an electron-deficient atom, and 1,2-anion shift is the one that the accepted atom of the migration group is a negative ion. In terms of the experimental facts and the calculation of the potential surfaces, in electron-deficient shift such as Beckmann or Baeyer-Villiger rearrangement, the migration occurs through a transition complex formed between the 7i-bond and the cation or electron-deficient migrating group, but in anion shift such as Wittig or Stevens rearrangement, the electron pair in it-orbit excites at first to π* orbit, and then the migration occurs through the new formed complex between the anion migration group and the vacant
基金Project Supported by Ministry of Education of China (the Key University Faculty Programm).
文摘The mass spectrometric behaviour of four cis- and trans-1a, 3-disuhsdtuted-1,1-dichloro-4-formyl-1a,2,3,4-tetrahydro-1H-azirino[1, 2-a] [1, 5]benzodiazepines has been studied with the aid of mass-analysed ion kinetic energy spectrometry and exact mass measurements under electron impact ionization. All compounds show a tendency to eliminate a chlorine atom from the aziridine ring, and then eliminate a neutral propene or styrene from the diazepine ring to yield azirino[1, 2b][1,3] benzimidazole ions. These azirino[1,2-a][1,5]benzodiazepines can also eliminate HCl, or Cl plus HCl simultaneously to undergo a ring enlargement rearrangement to yield 1,6-benzodiazocine ions, which further lose small molecular fragments, propyne or phenylacetylene, with rearrangement to give quinoxaline ions.
基金supported by the National Natural Science Foundation of China(22022114,21971261)the Key Project of Chinese National Programs for Fundamental Research and Development(2016YFA0602900)+3 种基金the Guang-dong Basic and Applied Basic Research Foundation(2020A1515010624)the Fundamental Research Funds for the Central Universities(20ykzd12)the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program(2017BT01Y093)the China Postdoctoral Science Foundation(2021M69360)。
文摘The semipinacol rearrangement is one of the classic yet useful synthetic tools in organic synthesis.However,semipinacol rearrangements involving heteroatom-migration are rare.Reported herein is a boryl-migratory semipinacol rearrangement of α-hydroxyallylboronates and α-hydroxypropargylboronates triggered by diverse halogen-,oxygen-,sulfur-and seleniumcontaining electrophiles.The protocol leads to a mild and facile access to organoborons bearing valuable functionalities.The σ(C-B)hyperconjugation is believed to be the key factor that leads to the observed exclusive chemoselectivity and enhanced reactivity.Synthetic utilities of the formed products were demonstrated.
