The synthesis of structurally diverse silacycles is crucial for the silicon-containing drug and agrochemical development.However,despite almost a century of synthetic endeavors,reaction processes that stereoselectivel...The synthesis of structurally diverse silacycles is crucial for the silicon-containing drug and agrochemical development.However,despite almost a century of synthetic endeavors,reaction processes that stereoselectively cleave and reconstruct the carbon-silicon bond in organosilicon precursors remain largely elusive.Herein we report a stereoselective silacyclization reaction through highly efficient Si-C bond cleavage and reconstruction.Our approach features a unique cavity-like molecular catalyst that facilitates the formation of cyclic silylpalladium intermediates,which undergo regioselective intramolecular cyclization under mild conditions.Notably,the TADDOLderived phosphoramidite ligand proves exceptionally effective,enabling the ultrarapid synthesis of novel Si-stereogenic silacycles with unprecedented enantioselectivity(up to 99%ee)and remarkable catalytic efficiency(TOF>17,280 h^(-1)at 1 mol% of palladium loading).This innovative methodology not only provides access to a diverse array of structurally new sila-N/O-heterocycles but also demonstrates exceptional utility in late-stage functionalization,allowing direct incorporation of silicon-stereogenic silacycle fragments into complex drug-like molecules.展开更多
Formal cross-dimerization of two different strained rings represents an innovative strategy toward specific ring systems that are otherwise inaccessible.Yet,formidable challenges remain in controlling the reactivity a...Formal cross-dimerization of two different strained rings represents an innovative strategy toward specific ring systems that are otherwise inaccessible.Yet,formidable challenges remain in controlling the reactivity and site-selectivity.Herein,we realized the reversal of site-selectivity in formal crossdimerization of benzocyclobutenones(BCBs)and silacyclobutanes(SCBs)by development of a nickel/magnesium synergistic catalytic system,in which the C(sp3)−C(carbonyl)bond of BCBs was exclusively cleaved,providing previously inaccessible eight-membered benzosilacycles.The catalytic cycle,the origin of this unconventional site-selectivity,and the role of MgCl2 have explicitly been elucidated by density functional theory calculations.Combined experimental and computational studies have clearly illustrated that the C1-C8 cleavage selectivity of BCBs in our reaction are mainly attributed to both the steric hindrance by introduction of substituents at the C3-and the proper choice of the Ni/Mg synergistic catalytic system.展开更多
基金supported by the grants of National Natural Science Foundation of China(grant nos.22361162606,22072035,and 22371060)the National Natural Science Foundation of China(NSFC)/Research Grants Council(RGC)Joint Research Scheme(grant no.N_CUHK426/23)+1 种基金Zhejiang Provincial Natural Science Foundation of China(grant no.LZ23B020002)Interdisciplinary Research Project of Hangzhou Normal University(grant no.2025JCXK02)are gratefully acknowledged.
文摘The synthesis of structurally diverse silacycles is crucial for the silicon-containing drug and agrochemical development.However,despite almost a century of synthetic endeavors,reaction processes that stereoselectively cleave and reconstruct the carbon-silicon bond in organosilicon precursors remain largely elusive.Herein we report a stereoselective silacyclization reaction through highly efficient Si-C bond cleavage and reconstruction.Our approach features a unique cavity-like molecular catalyst that facilitates the formation of cyclic silylpalladium intermediates,which undergo regioselective intramolecular cyclization under mild conditions.Notably,the TADDOLderived phosphoramidite ligand proves exceptionally effective,enabling the ultrarapid synthesis of novel Si-stereogenic silacycles with unprecedented enantioselectivity(up to 99%ee)and remarkable catalytic efficiency(TOF>17,280 h^(-1)at 1 mol% of palladium loading).This innovative methodology not only provides access to a diverse array of structurally new sila-N/O-heterocycles but also demonstrates exceptional utility in late-stage functionalization,allowing direct incorporation of silicon-stereogenic silacycle fragments into complex drug-like molecules.
基金grateful for financial support from the National Natural Science Foundation of China(grant nos.22071114,22022103,21871146,22122104,22193012,22188101,and 21933004)the National Key Research and Development Program of China(grant nos.2019YFA0210500 and 2021YFF0701700)+1 种基金the Frontiers Science Center for New Organic Matter,Nankai University(grant no.63181206)the Fundamental Research Funds for the Central Universities and Nankai University.
文摘Formal cross-dimerization of two different strained rings represents an innovative strategy toward specific ring systems that are otherwise inaccessible.Yet,formidable challenges remain in controlling the reactivity and site-selectivity.Herein,we realized the reversal of site-selectivity in formal crossdimerization of benzocyclobutenones(BCBs)and silacyclobutanes(SCBs)by development of a nickel/magnesium synergistic catalytic system,in which the C(sp3)−C(carbonyl)bond of BCBs was exclusively cleaved,providing previously inaccessible eight-membered benzosilacycles.The catalytic cycle,the origin of this unconventional site-selectivity,and the role of MgCl2 have explicitly been elucidated by density functional theory calculations.Combined experimental and computational studies have clearly illustrated that the C1-C8 cleavage selectivity of BCBs in our reaction are mainly attributed to both the steric hindrance by introduction of substituents at the C3-and the proper choice of the Ni/Mg synergistic catalytic system.
