A series of 2,4-dibromobutenes were synthesized by the reaction of methylenecyclopropanes with KBr in HOAc in the presence of dibenzoyl peroxide, providing an environment friendly method for the synthesis of 2,4-dibro...A series of 2,4-dibromobutenes were synthesized by the reaction of methylenecyclopropanes with KBr in HOAc in the presence of dibenzoyl peroxide, providing an environment friendly method for the synthesis of 2,4-dibromobutenes.展开更多
Aminochlorination of methylenecyclopropanes （MCPs） 1 can be achieved under CO2 atmosphere using N,N-dichlorotoluenesulfonamine （TsNCl2） as the nitrogen and halogen sources at room temperature to give the correspon...Aminochlorination of methylenecyclopropanes （MCPs） 1 can be achieved under CO2 atmosphere using N,N-dichlorotoluenesulfonamine （TsNCl2） as the nitrogen and halogen sources at room temperature to give the corresponding normal ring-remaining aminochlorinated products 2 along with/without the ring-opened aminochlorinated products 3 in moderate to good total yields. The present process takes the advantage of the green benign reaction conditions in the absence of any metal catalyst and solvent.展开更多
Methylenecyclopropanes are among the most robust building blocks in synthetic chemistry,but the study on(difluoromethylene)-cyclopropanes is rather limited,because of the difficulty in the synthesis of these compounds...Methylenecyclopropanes are among the most robust building blocks in synthetic chemistry,but the study on(difluoromethylene)-cyclopropanes is rather limited,because of the difficulty in the synthesis of these compounds.Herein,we report the invention of a novel carbene precursor,(1-diazo-2,2,2-trifluoroethyl)dimethyl(phenyl)silane(1a)and its application in the synthesis of(difluoromethylene)cyclopropanes.The reaction proceeds through photocatalyzed[2+1]cyclization of readily available alkenes and diazo compound 1a followed by the work-up of the reaction through the elimination of silyl fluoride.Both aromatic and aliphatic alkenes are tolerated by the mild reaction conditions,affording various(difluoromethylene)cyclopropanes in 44%–82%yield(>30 examples).Gram scale reaction and diversified downstream transformations highlight the synthetic potential of this methodology.The experimental and DFT calculations suggest the involvement of triplet carbene intermediate.展开更多
文摘A series of 2,4-dibromobutenes were synthesized by the reaction of methylenecyclopropanes with KBr in HOAc in the presence of dibenzoyl peroxide, providing an environment friendly method for the synthesis of 2,4-dibromobutenes.
基金Project supported by Shanghai Municipal Committee of Science and Technology （No. 08dj1400100-2）, National Basic Research Program of China （973） （No. 2009CB825300） and the National Natural Science Foundation of China （Nos. 21072206, 20472096, 20872162, 20672127, 20821002 and 20732008）.
文摘Aminochlorination of methylenecyclopropanes （MCPs） 1 can be achieved under CO2 atmosphere using N,N-dichlorotoluenesulfonamine （TsNCl2） as the nitrogen and halogen sources at room temperature to give the corresponding normal ring-remaining aminochlorinated products 2 along with/without the ring-opened aminochlorinated products 3 in moderate to good total yields. The present process takes the advantage of the green benign reaction conditions in the absence of any metal catalyst and solvent.
基金supported by the National Key Research and Development Program of China(2022YFA1506100)Shenzhen Science and Technology Program(JCYJ20220818100604009)Guangdong Basic and Applied Basic Research Foundation(2021A1515010105,2023A1515010601)。
文摘Methylenecyclopropanes are among the most robust building blocks in synthetic chemistry,but the study on(difluoromethylene)-cyclopropanes is rather limited,because of the difficulty in the synthesis of these compounds.Herein,we report the invention of a novel carbene precursor,(1-diazo-2,2,2-trifluoroethyl)dimethyl(phenyl)silane(1a)and its application in the synthesis of(difluoromethylene)cyclopropanes.The reaction proceeds through photocatalyzed[2+1]cyclization of readily available alkenes and diazo compound 1a followed by the work-up of the reaction through the elimination of silyl fluoride.Both aromatic and aliphatic alkenes are tolerated by the mild reaction conditions,affording various(difluoromethylene)cyclopropanes in 44%–82%yield(>30 examples).Gram scale reaction and diversified downstream transformations highlight the synthetic potential of this methodology.The experimental and DFT calculations suggest the involvement of triplet carbene intermediate.
