47 research outputs found
Highly Regioselective Indoline Synthesis under Nickel/Photoredox Dual Catalysis
Get PDFNickel/photoredox catalysis is used to synthesize indolines in one step from iodoacetanilides and alkenes. Very high regioselectivity for 3-substituted indoline products is obtained for both aliphatic and styrenyl olefins. Mechanistic investigations indicate that oxidation to Ni(III) is necessary to perform the difficult C–N bond-forming reductive elimination, producing a Ni(I) complex, which in turn is reduced to Ni(0). This process serves to further demonstrate the utility of photoredox catalysts as controlled single electron transfer agents in multioxidation state nickel catalysis.National Institute of General Medical Sciences (U.S.) (GM63755
Nickel-Catalyzed Mizoroki-Heck Reaction of Aryl Sulfonates and Chlorides with Electronically Unbiased Terminal Olefins: High Selectivity for Branched Products
Get PDFAchieving high selectivity in the Heck reaction of electronically unbiased alkenes has been a longstanding challenge. Using a nickel-catalyzed cationic Heck reaction, we were able to achieve excellent selectivity for branched products (≥19:1 in all cases) over a wide range of aryl electrophiles and aliphatic olefins. A bidentate ligand with a suitable bite angle and steric profile was key to obtaining high branched/linear selectivity, whereas the appropriate base suppressed alkene isomerization of the product. Although aryl triflates are traditionally used to access the cationic Heck pathway, we have shown that, by using triethylsilyl trifluoromethanesulfonate, we can effect a counterion exchange of the catalytic nickel complex, such that cheaper and more stable aryl chlorides, mesylates, tosylates, and sulfamates can be used to yield the same branched products with high selectivity.National Institute of General Medical Sciences (U.S.) (NIGMS (GM62755))National Institutes of Health (U.S.) (NIH Postdoctoral Fellowship)National Science Foundation (U.S.) (NSF Graduate Research Fellowship
Recent advances in homogeneous nickel catalysis
No full textTremendous advances have been made in nickel catalysis over the past decade. Several key properties of nickel, such as facile oxidative addition and ready access to multiple oxidation states, have allowed the development of a broad range of innovative reactions. In recent years, these properties have been increasingly understood and used to perform transformations long considered exceptionally challenging. Here we discuss some of the most recent and significant developments in homogeneous nickel catalysis, with an emphasis on both synthetic outcome and mechanism.National Science Foundation (U.S.) (Graduate Research Fellowship)National Institute of General Medical Sciences (U.S.) (NIGMS (GM62755)
The nickel-catalyzed Mizoroki-Heck reaction : high regioselectivity in Olefin migratory insertion and photoredox-enabled indoline formation
No full textThesis: Ph. D. in Organic Chemistry, Massachusetts Institute of Technology, Department of Chemistry, 2015.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis. VitaIncludes bibliographical references.[chemical formula and color illustrations ...] Achieving high selectivity in the Heck reaction of electronically unbiased alkenes has been a longstanding challenge. Using a nickel-catalyzed cationic Heck reaction, we were able to achieve excellent selectivity for branched products (>/=19:1 in all cases) over a wide range of aryl electrophiles and aliphatic olefins. A bidentate ligand with a suitable bite angle and steric profile was key to obtaining high branched/linear selectivity, while the appropriate base suppressed alkene isomerization of the product. Though aryl triflates are traditionally used to access the cationic Heck pathway, we have shown that by using triethylsilyl trifluoromethanesulfonate we can effect a counterion exchange of the catalytic nickel complex such that cheaper and more stable aryl chlorides, mesylates, tosylates, and sulfamates can be used to yield the same branched products with high selectivity. [chemical formula and color illustrations ...] Nickel/photoredox catalysis is used to synthesize indolines in one step from iodoacetanilides and alkenes. Very high regioselectivity for 3-substituted indoline products is obtained for both aliphatic and styrenyl olefins. Mechanistic investigations indicate that oxidation to Ni(III) is necessary to perform the difficult C-N bond-forming reductive elimination, producing a Ni(I) complex which in turn is reduced to Ni(0). This process serves to further demonstrate the utility of photoredox catalysts as controlled single electron transfer agents in multi-oxidation state nickel catalysis.by Sarah Z. Tasker.Ph. D. in Organic Chemistr
ChemInform Abstract: Highly Regioselective Indoline Synthesis under Nickel/Photoredox Dual Catalysis.
No full text
Highly Regioselective Indoline Synthesis under Nickel/Photoredox Dual Catalysis
No full textNickel/photoredox catalysis is used
to synthesize indolines in
one step from iodoacetanilides and alkenes. Very high regioselectivity
for 3-substituted indoline products is obtained for both aliphatic
and styrenyl olefins. Mechanistic investigations indicate that oxidation
to Ni(III) is necessary to perform the difficult C–N bond-forming
reductive elimination, producing a Ni(I) complex, which in turn is
reduced to Ni(0). This process serves to further demonstrate the utility
of photoredox catalysts as controlled single electron transfer agents
in multioxidation state nickel catalysis
Highly Regioselective Indoline Synthesis under Nickel/Photoredox Dual Catalysis
No full textNickel/photoredox catalysis is used
to synthesize indolines in
one step from iodoacetanilides and alkenes. Very high regioselectivity
for 3-substituted indoline products is obtained for both aliphatic
and styrenyl olefins. Mechanistic investigations indicate that oxidation
to Ni(III) is necessary to perform the difficult C–N bond-forming
reductive elimination, producing a Ni(I) complex, which in turn is
reduced to Ni(0). This process serves to further demonstrate the utility
of photoredox catalysts as controlled single electron transfer agents
in multioxidation state nickel catalysis
ChemInform Abstract: Nickel‐Catalyzed Mizoroki—Heck Reaction of Aryl Sulfonates and Chlorides with Electronically Unbiased Terminal Olefins: High Selectivity for Branched Products.
No full text
