A new nucleophilic 1,3-rearrangement is observed when treating 2-methoxyquinolino-3-lithium with an α-C substituted deoxybenzoin,and this rearrangement yielded an unusual 3,4-disubstituted 3,4-dihydroquinoline.Severa...A new nucleophilic 1,3-rearrangement is observed when treating 2-methoxyquinolino-3-lithium with an α-C substituted deoxybenzoin,and this rearrangement yielded an unusual 3,4-disubstituted 3,4-dihydroquinoline.Several similar reactions were designed and executed to investigate this novel 1,3-rearrangement,and a mechanism involving a nucleophilic addition and a following 1,3-rearrangement with an unusual dearomatization on the quinoline ring is proposed.展开更多
1,2-rearrangements of carbenes :CCH_2X(X=CH_2, NH and O) are studied by using ab initio gradient method. Heteroatoms N and O stabilize the carbene and decrease its reactivity, mainly by changing frontier molecular orb...1,2-rearrangements of carbenes :CCH_2X(X=CH_2, NH and O) are studied by using ab initio gradient method. Heteroatoms N and O stabilize the carbene and decrease its reactivity, mainly by changing frontier molecular orbitals, but retain the way of the reaction. The reaction starts from the attack of the migrating hydrogen on the carbene p AO and ends with the entrance of the hydrogen into the carbene σ orbital. Reactivities are in the order of X=CH_2>NH>O. The reaction is exothermic or endothermic according to whether the product is a 4n+2 or 4n π electron molecule.展开更多
A transition-metal-free strategy for the synthesis of tetrasubstituted furans is reported.Promoted by boron trifluo-ride diethyl etherate,the reaction of alkynyl sulfoxides with ynamides/ynol ethers proceeded via a ca...A transition-metal-free strategy for the synthesis of tetrasubstituted furans is reported.Promoted by boron trifluo-ride diethyl etherate,the reaction of alkynyl sulfoxides with ynamides/ynol ethers proceeded via a cascade process including cross-coupling of the two reactants,[3,3]-sulfonium rearrangement,and 5-exo-dig heterocyclization,leading to tetrasubstituted furan products.The resultant α-alkylthio groups can be used for further functionalization,such as to introduce other alkyl/aryl groups.展开更多
A formal total synthesis of iridoid 9-deoxygelsemide has been accomplished. Our approach features the use of （S）-carvone as starting material, Favorskii rearrangement to construct the functionalized cyclopentane cor...A formal total synthesis of iridoid 9-deoxygelsemide has been accomplished. Our approach features the use of （S）-carvone as starting material, Favorskii rearrangement to construct the functionalized cyclopentane core, Chugeav elimination to introduce the endocyclic double bond, and the ring-opening reaction of epoxide to build the second five-membered ring.展开更多
基金‘‘The National High-Tech Research and Development Program (‘‘863’’Program) of China’’No. 2012AA020302) for financial support
文摘A new nucleophilic 1,3-rearrangement is observed when treating 2-methoxyquinolino-3-lithium with an α-C substituted deoxybenzoin,and this rearrangement yielded an unusual 3,4-disubstituted 3,4-dihydroquinoline.Several similar reactions were designed and executed to investigate this novel 1,3-rearrangement,and a mechanism involving a nucleophilic addition and a following 1,3-rearrangement with an unusual dearomatization on the quinoline ring is proposed.
基金This project was supported by the National Natural Science Foundation of China.
文摘1,2-rearrangements of carbenes :CCH_2X(X=CH_2, NH and O) are studied by using ab initio gradient method. Heteroatoms N and O stabilize the carbene and decrease its reactivity, mainly by changing frontier molecular orbitals, but retain the way of the reaction. The reaction starts from the attack of the migrating hydrogen on the carbene p AO and ends with the entrance of the hydrogen into the carbene σ orbital. Reactivities are in the order of X=CH_2>NH>O. The reaction is exothermic or endothermic according to whether the product is a 4n+2 or 4n π electron molecule.
文摘A transition-metal-free strategy for the synthesis of tetrasubstituted furans is reported.Promoted by boron trifluo-ride diethyl etherate,the reaction of alkynyl sulfoxides with ynamides/ynol ethers proceeded via a cascade process including cross-coupling of the two reactants,[3,3]-sulfonium rearrangement,and 5-exo-dig heterocyclization,leading to tetrasubstituted furan products.The resultant α-alkylthio groups can be used for further functionalization,such as to introduce other alkyl/aryl groups.
文摘A formal total synthesis of iridoid 9-deoxygelsemide has been accomplished. Our approach features the use of （S）-carvone as starting material, Favorskii rearrangement to construct the functionalized cyclopentane core, Chugeav elimination to introduce the endocyclic double bond, and the ring-opening reaction of epoxide to build the second five-membered ring.
