Hexaflouroisopropanol - a solvent of high ionizing power and low nucleophilicity

Schadt, Frank L.; Schleyer, Paul von Ragué; Bentley, T. William

doi:10.1016/s0040-4039(01)92248-8

Cited by 58 publications

(27 citation statements)

References 24 publications

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“…Interestingly, the rate of the reaction decreased with larger quantities of n -Bu 4 NOAc, ultimately leading to complete loss of reactivity with 20 equiv of n -Bu 4 NOAc (Table 3, entry 5). 41 On the basis of these experiments, it can be concluded that the benzylic chloriranium ion, if formed, is in equilibrium with an open benzylic carbocation, giving rise to poorly selective nucleophilic capture and formation of unwanted elimination products.…”

Section: Resultsmentioning

confidence: 99%

Toward Catalytic, Enantioselective Chlorolactonization of 1,2-Disubstituted Styrenyl Carboxylic Acids

et al. 2016

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An investigation into the use of Lewis base catalysis for the enantioselective chlorolactonization of 1,2-disubstituted alkenoic acids is described. Two mechanistically distinct reaction pathways for catalytic chlorolactonization have been identified. Mechanistic investigation revealed that tertiary amines predominately operate as Brønsted rather than Lewis bases. Two potential modes of activation have been identified that involve donation of electron density of the carboxylate to the C=C bond as well hydrogen bonding to the chlorinating agent. Sulfur- and selenium-based additives operate under Lewis base catalysis; however, due to the instability of the intermediate benzylic chloriranium ion, chlorolactonization suffers from low chemo-, diastereo-, and enantioselectivities. Independent generation of the benzylic chloriranium ion shows that it is in equilibrium with an open cation, which leads to low specificities in the nucleophilic capture of the intermediate.

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Section: Resultsmentioning

confidence: 99%

Toward Catalytic, Enantioselective Chlorolactonization of 1,2-Disubstituted Styrenyl Carboxylic Acids

et al. 2016

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“…Subsequent substitution with retention of configuration of the benzylic chlorine atom in 6 by a hydroxyl group was achieved with good stereocontrol (9:1 anti/syn to ring C) under S N 1 conditions, by heating a solution of 6 in water/ hexafluoroisopropanol. [22] Dechlorination of the gem-dichloro motif with zinc dust afforded tricyclic lactone 5 in a 91 % overall yield from 6. Careful formylation of 5, followed by coupling in the same pot with D-ring precursor 4 by controlling the temperature, completed the synthesis to provide compound 3, identified as (À)-solanacol (see below) and (À)-2'-epi-solanacol (15) in a 76 % combined yield.…”

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confidence: 99%

Stereochemistry, Total Synthesis, and Biological Evaluation of the New Plant Hormone Solanacol

Chen

Boyer

Rameau

et al. 2010

Chemistry A European J

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Poly(9,9‐dioctylfluorene) (PFO) with Mn values above 100 000 g mol−1 in a toluene/water system and Mn values up to 600 000 g mol−1 in a THF/water system has been obtained by improved Suzuki polycondensation using a new kind of amphipathic palladium catalyst with self‐phase‐transfer features, which could overcome the disadvantage caused by the immiscible biphasic mixture and accelerate the transmetalation step (see figure).

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“…If the three assumptions above are valid, secondary substrates do in fact react by the S N 2 (intermediate) mechanism because the NSA values are larger than one, some substantially so. Two additional comments are in order: (1) Many NSA values in (CF 3 ) 2 CHOH-H 2 O (97:3 v/v) are less than 1, suggesting that this solvent mixture would also have been a good choice for a nonnucleophilic solvent (Schadt et al 1974); (2) A plot of k H /k D , the a secondary kinetic isotope effect, for a series of secondary tosylates, versus log(NSA) yielded a very good straight line, suggesting that these two quantities can be interpreted in the same manner, i.e. that secondary substrates react in most solvents by a merged mechanism.…”

Section: -Octyl Tosylatementioning

confidence: 99%

Do the solvolysis reactions of secondary substrates occur by the SN1 or SN2 mechanism: or something else?

Pagni

2011

Found Chem

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Primary and methyl aliphatic halides and tosylates undergo substitution reactions with nucleophiles in one step by the classic S N 2 mechanism, which is characterized by second-order kinetics and inversion of configuration at the reaction center. Tertiary aliphatic halides and tosylates undergo substitution reactions with nucleophiles in two (or more) steps by the classic S N 1 mechanism, which is characterized by first-order kinetics and incomplete inversion of configuration at the reaction center due to the presence of ion pairs. When the nucleophile is also the solvent, the substitution reaction is called a solvolysis, and both the S N 2 and S N 1 reactions now obey first-order kinetics. Schleyer and Bentley have provided solid, but not conclusive, evidence that secondary substrates undergo solvolysis by a merged mechanism, one that blends characteristics of both the S N 2 and S N 1 mechanisms. The following paper presents the history of their sustained pursuit of a merged mechanism and subsequent rebuttals to this claim. Several issues related to the philosophy and sociology of science are also discussed.

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Hexaflouroisopropanol - a solvent of high ionizing power and low nucleophilicity

Cited by 58 publications

References 24 publications

Toward Catalytic, Enantioselective Chlorolactonization of 1,2-Disubstituted Styrenyl Carboxylic Acids

Toward Catalytic, Enantioselective Chlorolactonization of 1,2-Disubstituted Styrenyl Carboxylic Acids

Stereochemistry, Total Synthesis, and Biological Evaluation of the New Plant Hormone Solanacol

Do the solvolysis reactions of secondary substrates occur by the SN1 or SN2 mechanism: or something else?

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