Mechanistic Studies of Proton‐Donor Coordination to Samarium Diiodide

Teprovich, Joseph A.; Balili, Marielle Nicole C.; Pintauer, Tomislav; Flowers, Robert A.

doi:10.1002/anie.200702571

Cited by 46 publications

(32 citation statements)

References 28 publications

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“…The enthalpy of complexation for water and Et 3 N measured through ITC experiments was found to be comparable (−2.5 kcal mol −1 for water and −3.3 kcal mol −1 for Et 3 N). It was shown previously that introduction of alkyl group one oxygen has significant deleterious impact on the coordinating ability . We have also seen similar phenomenon when a methyl group was added on the nitrogen of ethanolamine (Figure ).…”

Section: Resultssupporting

confidence: 85%

Aza versus Oxophilicity of SmI₂: A Break of a Paradigm

Maity

Flowers

Hoz

2017

Chemistry A European J

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Ligands that coordinate to SmI through oxygen are prevalent in the literature and make up a significant portion of additives employed with the reagent to perform reactions of great synthetic importance. In the present work a series of spectroscopic, calorimetric and kinetic studies demonstrate that nitrogen-based analogues of many common additives have a significantly higher affinity for Sm than the oxygen-based counterparts. In addition, electrochemical experiments show that nitrogen-based ligands significantly enhance the reducing power of SmI . Overall, this work demonstrates that the use of nitrogen-based ligands provides a useful alternative approach to enhance the reactivity of reductants based on Sm .

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Section: Resultssupporting

confidence: 85%

Aza versus Oxophilicity of SmI₂: A Break of a Paradigm

Maity

Flowers

Hoz

2017

Chemistry A European J

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“…These data support a mechanism in which the driving force for the increased reactivity of SmI 2 upon the addition of the coordinating proton donors is due to solvent or iodide displacement, similar to that observed with the addition of HMPA to SmI 2 . 51,67 With the mechanistic data on proton donors in hand, it is instructive to consider the observations described herein in the context of previous findings reported in the literature. One of the striking features of this work is the observation that water has an unusually high affinity for SmI 2 and competes with THF for coordination at very low concentrations compared with the bulk solvent.…”

Section: Scheme 5 First Two Steps In the Reduction Of Acetophenone Bymentioning

confidence: 90%

Mechanistic Studies on the Roles of Cosolvents and Additives in Samarium(II)-Based Reductions

Flowers¹

2008

Synlett

171

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This account describes work, performed by my research group during the past decade, designed to understand the mechanistic roles of cosolvents and additives in reductions involving samarium(II) iodide (SmI 2 ). Emphasis is placed on studies designed to elucidate the roles of the cosolvent hexamethylphosphoramide (HMPA) and proton donors (water, alcohols, and glycols) in the mechanisms of important bond-forming reactions and reductions initiated by SmI 2 .

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“…In most of the papers reporting the reaction of SmI 2 with benzyl halides, the benzylic system was used as a model or a vehicle to explore the landscape of SmI 2 capabilities. A number of examples of these are the lifetime of excited SmI 2 ,6 the issue of inner sphere versus outer sphere electron transfer,7 as a mechanistic probe for the reactions of SmI 2 –water,8 the effect of crown ethers on SmI 2 reactions,9 the effect of water,10 glyme,11 hexamethylphosphoramide (HMPA)12 and so on.…”

Section: Introductionmentioning

confidence: 99%

Reversed Electron Apportionment in Mesolytic Cleavage: The Reduction of Benzyl Halides by SmI₂

Yitzhaki

Hoz

2015

Chemistry A European J

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The paradigm that the cleavage of the radical anion of benzyl halides occurs in such a way that the negative charge ends up on the departing halide leaving behind a benzyl radical is well rooted in chemistry. By studying the kinetics of the reaction of substituted benzylbromides and chlorides with SmI2 in THF it was found that substrates para-substituted with electron-withdrawing groups (CN and CO2 Me), which are capable of forming hydrogen bonds with a proton donor and coordinating to samarium cation, react in a reversed electron apportionment mode. Namely, the halide departs as a radical. This conclusion is based on the found convex Hammett plots, element effects, proton donor effects, and the effect of tosylate (OTs) as a leaving group. The latter does not tend to tolerate radical character on the oxygen atom. In the presence of a proton donor, the tolyl derivatives were the sole product, whereas in its absence, the coupling dimer was obtained by a SN 2 reaction of the benzyl anion on the neutral substrate. The data also suggest that for the para-CN and CO2 Me derivatives in the presence of a proton donor, the first electron transfer is coupled with the proton transfer.

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Mechanistic Studies of Proton‐Donor Coordination to Samarium Diiodide

Cited by 46 publications

References 28 publications

Aza versus Oxophilicity of SmI₂: A Break of a Paradigm

Aza versus Oxophilicity of SmI₂: A Break of a Paradigm

Mechanistic Studies on the Roles of Cosolvents and Additives in Samarium(II)-Based Reductions

Reversed Electron Apportionment in Mesolytic Cleavage: The Reduction of Benzyl Halides by SmI₂

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Mechanistic Studies of Proton‐Donor Coordination to Samarium Diiodide

Cited by 46 publications

References 28 publications

Aza versus Oxophilicity of SmI2: A Break of a Paradigm

Aza versus Oxophilicity of SmI2: A Break of a Paradigm

Mechanistic Studies on the Roles of Cosolvents and Additives in Samarium(II)-Based Reductions

Reversed Electron Apportionment in Mesolytic Cleavage: The Reduction of Benzyl Halides by SmI2

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Product

Resources

About

Aza versus Oxophilicity of SmI₂: A Break of a Paradigm

Aza versus Oxophilicity of SmI₂: A Break of a Paradigm

Reversed Electron Apportionment in Mesolytic Cleavage: The Reduction of Benzyl Halides by SmI₂