Polar Addition to C=C Group: Why Is Anti-Markovnikov Hydroboration–Oxidation of Alkenes Not "Anti-"?

Ilich, Predrag-Peter; Rickertsen, Lucas S.; Becker, Erienne

doi:10.1021/ed083p1681

Cited by 11 publications

(8 citation statements)

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“…The principal goal of our work published in this Journal (1) has been to show that electrophilic addition reactions to alkenes can be adequately described by the standard parameters of chemical reactivity: charge distribution of the substrate and energy of the reaction-determining intermediate. Through the analysis of six representative addition reactions we also show that the term "anti-Markovnikov" is incorrect and redundant.…”

Section: Literature Citedmentioning

confidence: 99%

Markovnikov's Rule

Ilich

2007

J. Chem. Educ.

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Letters Markovnikov's RuleThe recent contribution by Ilich, Rickertsen, and Becker (1) provides abundant reasons for abandoning the description of addition reactions and their products as "Markovniknov" or (even worse) "anti-Markovnikov". In a recent review (2) I have surveyed the history of this usage and concluded that its use in teaching has long outlived its utility. The deeper understanding of these reactions as involving appropriate reactive intermediates (e.g., carbocations), whose relative stabilities can be understood on a general basis, should have superseded the use of an empirical rule that is often inapplicable, often restated in ways unrecognizable to its originator, and never an adequate substitute for understanding. If we wish students to understand organic reactivity as a whole, we should not provide them with this cognitive crutch. If our use of the description of one product as a "Markovnikov product" is meant to honor a great 19th century chemist, what is the effect of describing another as an "anti-Markovnikov product"? Unfortunately, the authors of the article draw back from the simple conclusion that the rule should be abandoned, but rather attempt once again to restate or reformulate it, while clinging to the name. In agreement with Gooch (3), I urge teachers and textbook authors to move past Markovnikov's rule once and for all. The author replies: Literature CitedThe principal goal of our work published in this Journal (1) has been to show that electrophilic addition reactions to alkenes can be adequately described by the standard parameters of chemical reactivity: charge distribution of the substrate and energy of the reaction-determining intermediate. Through the analysis of six representative addition reactions we also show that the term "anti-Markovnikov" is incorrect and redundant. Dr. Kerber's plea-and the stronger message of his article published in Foundations of Chemistry (2)-is to avoid artificial and non-pedagogical extensions of the Markovnikov rule and phase it out from organic chemistry textbooks. We completely agree with and support Dr. Kerber's call for making teaching and learning of second-year organic chemistry more accurate, more effective, and less difficult.However, beyond undergraduate chemistry courses and textbooks there is a vast and very important world of practicing organic chemists. They keep using the "Markovnikov terminology" as useful shorthand for classification of products in an ever-increasing number of what seem to be electrophilic addition reactions. We posit that the use of this terminology is often incorrect. Our extensive analysis (submitted for publication) of the energy-charge profile of a number of reactions reported as "anti-Markovnikov" suggest that they follow mechanisms different from those of the reactions originally described some 140 years ago by Vladimir Markovnikov. However, we also feel that more insight into the mechanisms of addition reactions to alkenes is needed before requesting radical changes in the organic chemistry terminology...

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Section: Literature Citedmentioning

confidence: 99%

Markovnikov's Rule

Ilich

2007

J. Chem. Educ.

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“…As the anti-Markovnikov rule follows the same general principle as the Markovnikov rule [23] in terms of the most energetically favorable reaction pathway being determined by the attractive dipole-dipole interactions within a carbon-carbon double bond and the reacting X-H substituent, our results therefore provide an exception (on the basis of F6, I6, and J6) to these rules in general. We found that the Lewis acid borane, and the second remaining double bond with Lewis base properties, resembling frustrated Lewis pair-type moieties, worked synergistically to stabilize allyl-π bond interactions resulting in the unexpected selectivity.…”

Section: Discussionmentioning

confidence: 51%

“…1 and assuming a kinetically controlled mechanism, we can predict the most favorable isomers computationally [21,22]. Previous computational studies have also pointed out the fact that the final thermodynamically favored products might not reflect the selectivity of the kinetically favored hydroboration reactions [23] and emphasized the importance of dynamical effects beyond transition state theory [24][25][26].…”

Section: Monohydroboration Products Of Dienesmentioning

confidence: 90%

“…However, in cyclic dienes, especially those which are symmetrical, the regioselectivity is not immediately obvious owing to the equal number of hydrogens on both sides of the carboncarbon double bond. A key relationship was previously highlighted between the reacting carbon atomic charge and the energy of the intermediates at the transition state [23]. Instead of analyzing the charge distribution of the intermediates, here we hypothesized that the charge density of the reacting dienes would mainly determine the product selectivity, corresponding to the reaction with the lowest transition state barrier.…”

Section: Monohydroboration Products Of Dienesmentioning

confidence: 98%

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Deviation from the anti-Markovnikov rule: a computational study of the regio- and stereoselectivity of diene hydroboration reactions

et al. 2015

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not follow the anti-Markovnikov rule. We proceed to show that in addition to the polarity of the double bonds within a molecule, in this case, the conjugation with the allyl double bond and the specific geometric features of the cyclohexane ring were key stabilizing factors for the unexpected transition state preference, resulting in a regioselectivity that is in quantitative agreement with previous experimental data. Our results further indicated that Re-face attacks and steric factors due to substituents of the substrate influenced mainly the stereoselective outcome of the reaction, also affecting the pathways available to proceed through to complete the hydroboration process.

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“…[4] Moreover,even in terms of electrophilic additions to alkenes, the options are wider than just following the stability of carbocations,a nd am ore competent picture can only be drawn through the inclusion of quantum chemical modeling of reaction pathways. [5] Markovnikov's Rule in the Early Literature Theh istory of the actual usage of this rule in chemical literature is rather intriguing. Although the rule comes from the early history of organic chemistry,i ts use initially was extremely rare,and mostly confined to textbooks.Only at the very end of the 19th Century did Arthur Michael undertake to review all the trends established in organic reactivity and paid careful attention to Markovnikovsm ajor contributions.H e admitted that Markovnikov emphasizes the mutual influence ("der gegenseitig Einfluss") of atoms in organic molecules as ak ey principle in all reasoning about the reactivity and selectivity of organic transformations.…”

Section: Introductionmentioning

confidence: 99%

Towards the 150th Anniversary of the Markovnikov Rule

Beletskaya

Nenajdenko

2019

Angewandte Chemie

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The Markovnikov rule,k nownt oe very student of organic chemistry,w as formulated 150 years ago,i n1 869. During its long history (almost as long as the history of organic chemistry itself), attitudes towards this famous statement of chemical reactivity have evolved from indifference up to the 1930s,t hrough common acceptance as au seful educational paradigm with marginal use in researchu pt ot he 1990s,t oi ts vigorous relauncha sa ni mportant designation of regioselectivity in the last few decades.The unexpected new popularity of the classical rule is accounted for by the rapid expansion in catalytic addition reactions and their critical importance as highly effective atom-economical, regioselective methods in modern organic synthesis.Ah istorical outline of the life and achievements of Vladimir Markovnikov is included to reveal the very wide scope of his interests as well as his prophetic predictions on structure,reactivity,selectivity,stereochemistry, and other key issues of organic chemistry.

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Polar Addition to C=C Group: Why Is Anti-Markovnikov Hydroboration–Oxidation of Alkenes Not "Anti-"?

Cited by 11 publications

References 5 publications

Markovnikov's Rule

Markovnikov's Rule

Deviation from the anti-Markovnikov rule: a computational study of the regio- and stereoselectivity of diene hydroboration reactions

Towards the 150th Anniversary of the Markovnikov Rule

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