Kinetics of intramolecular additions of the aminyl radicals to carbonyl groups and subsequent ring opening

Kim, Sunggak; Yoon, Kwang Sub; Kim, Sung Soo; Seo, Hyo Seok

doi:10.1016/0040-4020(95)00459-l

Cited by 24 publications

(8 citation statements)

References 17 publications

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“…Though there is not a lot data on radical decyclization for oxo‐cyclohexenyl systems, found evidence derived from cyclo‐isomerization kinetics and ring‐opening in different systems indicates that ring opening may possess rate constants with log magnitudes in the range of −1 to 3, being closer to B3LYP/6‐31G(d) estimations. Additionally, orders of B3LYP estimated rates for radical addition are in better agreement with experimental data for similar systems where reacting radical and alkene differ by nucleophilic properties …”

Section: Resultsmentioning

confidence: 83%

“…Rate constants of MAN addition to cyclic radicals at step n. 75 estimated by M06-2X/6-311+G(d) is higher by 1-2 orders, for B3LYP/6-31G(d) absolute log magnitude being in the range of 3-4 for m5m cycles, and 5-6 for m6-rings. Though there is not a lot data on radical decyclization for oxo-cyclohexenyl systems, found evidence derived from cycloisomerization kinetics and ring-opening in different systems [64][65][66][67][68] indicates that ring opening may possess rate constants with log magnitudes in the range of −1 to 3, being closer to B3LYP/6-31G(d) estimations. Additionally, orders of B3LYP estimated rates for radical addition are in better agreement with experimental data for similar systems where reacting radical and alkene differ by nucleophilic properties.…”

Section: Microkinetic Study Of Cyclocopolymerization Routesmentioning

confidence: 96%

“…For example, Hanns Fischer and Leo Radom referred to surprising precision of DFT B3LYP/6-31G(d) for modeling kinetics of radical addition reactions, [63] and it was observed as well in our recent work. [26] In the current work we come across significant difference between DFT M06-2X/6-311+G(d) and B3LYP/6-31G(d) results on rate constants for two key polymerization steps, that make significant difference in estimated polymer compositions: Though there is not a lot data on radical decyclization for oxo-cyclohexenyl systems, found evidence derived from cycloisomerization kinetics and ring-opening in different systems [64][65][66][67][68] indicates that ring opening may possess rate constants with log magnitudes in the range of −1 to 3, being closer to B3LYP/6-31G(d) estimations. Additionally, orders of B3LYP estimated rates for radical addition are in better agreement with experimental data for similar systems where reacting radical and alkene differ by nucleophilic properties.…”

Section: Microkinetic Study Of Cyclocopolymerization Routesmentioning

confidence: 99%

See 2 more Smart Citations

How to Fight Kinetics in Complex Radical Polymerization Processes: Theoretical Case Study of Poly(divinyl ether‐alt‐maleic anhydride)

Bolshchikov

Цветков

Alikhanova

et al. 2019

Macro Chemistry & Physics

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Products of free‐radical polymerization (FRP) are usually not regulated on the molecular scale, consisting of blocks obtained through the fastest kinetic scheme pathways. The side or kinetically restricted products can be a source of impurities in a complex FRP case, or possess new properties if isolated solely. FRP synthesis of poly(divinyl ether‐alt‐maleic anhydride), known as “DIVEMA”, serves as a polymerization example with such kinetic and thermodynamic complexities. Uncertainty in factors regulating polymer structure is a challenge in advancement “DIVEMA” derivatives toward medical practice. In‐depth investigation via quantum‐chemical and molecular mechanics methods unveils mechanistic aspects of polymer stereoisomerism and confirms possible isolation of thermodynamically or kinetically controlled products on a large data set. Strategies toward regulation of 5‐exo/6‐endo cycloisomerism are theorized and then studied via microkinetic modeling. Thermodynamically controlled products can be isolated utilizing lower monomer concentrations, in range of 10−3 to 10−1 m, and/or application of a complexing agent that is better to realize via solvents, capable of formation π‐ and σ‐radical complexes. Change of electrophilic monomer is proposed as an approach for designing more molecularscale adjustable copolymerization processes. Methodology, obtained results, and conclusions for “DIVEMA” can be valuable to control other FRP processes on the molecular scale, unlocking polymers with improved or new functionalities.

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Section: Resultsmentioning

confidence: 83%

Section: Microkinetic Study Of Cyclocopolymerization Routesmentioning

confidence: 96%

Section: Microkinetic Study Of Cyclocopolymerization Routesmentioning

confidence: 99%

See 1 more Smart Citation

How to Fight Kinetics in Complex Radical Polymerization Processes: Theoretical Case Study of Poly(divinyl ether‐alt‐maleic anhydride)

Bolshchikov

Цветков

Alikhanova

et al. 2019

Macro Chemistry & Physics

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“…107 For instance, macrocyclic lactams are obtained in excellent yields via a ring expansion process developed by Kim (Scheme 8.41 ,top). 77 Radical cyclization of tributylstannylaminyl radicals generated from azides to carbonyl compounds, 109 nitriles and alkenes 110 are reported. 77 Radical cyclization of tributylstannylaminyl radicals generated from azides to carbonyl compounds, 109 nitriles and alkenes 110 are reported.…”

Section: Radical Reactions Of Organic Azides With Tributyltin Hydridementioning

confidence: 99%

Radical Chemistry with Azides

Jimeno

Renaud

2009

Organic Azides

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Organic azides represent a very interesting class of compounds since they are precursor of a wide range of nitrogen containing organic molecules. 1 Moreover, they possess a unique reactivity pattern orthogonal to many other organic functional groups. This assessment is also true in the fi eld of radical chemistry. For instance, azides can be considered as protected amino groups that are perfectly tolerated in C -C bond forming reactions. This is illustrated by the synthesis of ( − ) -batzelladine D recently disclosed by P.A. Evans. 2 In this synthesis, a pyrrolo[1,2f]pyrimidine is built via a 5exo trig radical cyclization. The two azido substituents present in the molecule are not reduced under the reaction conditions used to run the cyclization (tributyltin hydride and triethylborane in the presence of air at room temperature) (Scheme 8.1 ).The stability of azides in radical reactions is further illustrated by the radical fragmentation of carbohydrate anomeric alkoxyl radicals bearing an azido substituent at position 3 reported by Suarez (Scheme 8.2 ). 3,4 After fragmentation, the 2 -azido -substituted radical is iodinated and no β -fragmentation of the azide is observed.However, under suitable conditions, azides react with a variety of radicals and this is the basis of several useful synthetic procedures for the formation of carbon -nitrogen bonds. For instance, synthesis of azides by radical addition of an azidyl radical to alkenes (Scheme 8.3 a) and by reaction of an alkyl radical with an azidating reagent (Scheme 8.3 b) will be presented. The reduction of azides leading to aminyl radicals (Scheme 8.3 c) and the addition of alkyl radicals to alkyl azides (Scheme 8.3 d) will also be discussed.

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“…We hypothesized that cascades beginning with cyclization of the relatively nucleophilic 16 aminyl radicals would have lower barriers when cyclizing with electron deficient olefins than with non-activated olefins. 17 Findings that enones analogous to substrate 1 cyclized efficiently, while the corresponding allylic alcohol 14 led only to N–Cl reduction (R 2 N–Cl → R 2 N–H) were consistent with our hypothesis but were insufficient to provide insight into 5-exo and 6-exo cyclizations of conformationally unbiased substrates.…”

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confidence: 99%

Synthetic and Computational Study of Tin-Free Reductive Tandem Cyclizations of Neutral Aminyl Radicals

et al. 2018

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5-exo, 5-exo Cyclizations of conformationally unbiased propargylic aminyl radicals proceed with excellent yield, chemoselectiv ity, and diastereoselectivity under tin-free reductive cyclization conditions, regardless of the electronic environments and intermediate radical stabilization resulting from various olefin substituents. These conditions avoid the need for slow addition of initiator and reductant. By contrast, analogous 6-exo, 5-exo cyclizations require substituents capable of intermediate radical stabilization to avoid premature reduction products. These experimental results are corroborated by computations that further establish the reactivity of these aminyl radicals upon exposure to tin-free cyclization conditions.

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Kinetics of intramolecular additions of the aminyl radicals to carbonyl groups and subsequent ring opening

Cited by 24 publications

References 17 publications

How to Fight Kinetics in Complex Radical Polymerization Processes: Theoretical Case Study of Poly(divinyl ether‐alt‐maleic anhydride)

How to Fight Kinetics in Complex Radical Polymerization Processes: Theoretical Case Study of Poly(divinyl ether‐alt‐maleic anhydride)

Radical Chemistry with Azides

Synthetic and Computational Study of Tin-Free Reductive Tandem Cyclizations of Neutral Aminyl Radicals

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