Substituent Effects in the Silylation of Secondary Alcohols: A Mechanistic Study

Marín‐Luna, Marta; Patschinski, Pascal; Zipse, Hendrik

doi:10.1002/chem.201803014

Cited by 22 publications

(16 citation statements)

References 47 publications

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“…The free energy surface calculated for secondary alcohol 1a at the SMD(CHCl 3 )/DLPNO–CCSD(T)/def2-TZVPP//SMD(CHCl 3 )/B3LYP-D3/6-31+G(d) level of theory is shown in Figure (for details, see Supporting Information). In line with earlier theoretical studies, catalyst 4 is here assumed to act as a Lewis rather than a Brønsted base. , It is furthermore assumed that the role of the auxiliary base Et 3 N is restricted to the out-of-cycle regeneration of protonated catalysts. This assumption has been confirmed in earlier related studies .…”

Section: Resultsmentioning

confidence: 90%

Size-Driven Inversion of Selectivity in Esterification Reactions: Secondary Beat Primary Alcohols

2021

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Relative rates for the Lewis base-mediated acylation of secondary and primary alcohols carrying large aromatic side chains with anhydrides differing in size and electronic structure have been measured. While primary alcohols react faster than secondary ones in transformations with monosubstituted benzoic anhydride derivatives, relative reactivities are inverted in reactions with sterically biased 1-naphthyl anhydrides. Further analysis of reaction rates shows that increasing substrate size leads to an actual acceleration of the acylation process, the effect being larger for secondary as compared to primary alcohols. Computational results indicate that acylation rates are guided by noncovalent interactions (NCIs) between the catalyst ring system and the DED substituents in the alcohol and anhydride reactants. Thereby stronger NCIs are formed for secondary alcohols than for primary alcohols.

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Section: Resultsmentioning

confidence: 90%

Size-Driven Inversion of Selectivity in Esterification Reactions: Secondary Beat Primary Alcohols

2021

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“…There is currently considerable interest in elucidating the effect of London dispersion on the structural, energetic, and chemical properties of organic, organometallic, and inorganic compounds. ,, While the influence of attractive dispersive interactions can be substantial, in particular in the gas phase, there is evidence that the effect can be attenuated by solvents . A study of the chemoselectivity of the reaction between secondary alcohols of variable size with carboxylic acid chlorides catalyzed by 9-azajulolidine reported by Zipse et al − observed that the more sizeable aryl-substituted alcohols show higher selectivities due to π–π and dispersion interactions. The lengths of alkyl chains only had minor influence on the selectivities …”

Section: Introductionmentioning

confidence: 99%

Synthesis and Photodimerization of 2- and 2,3-Disubstituted Anthracenes: Influence of Steric Interactions and London Dispersion on Diastereoselectivity

et al. 2019

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There is increased evidence that the effect of bulky groups in organic, organometallic, and inorganic chemistry is not only repulsive but can be attractive because of London dispersion interactions. The influence of the size of primary alkyl substituents in 2- and 2,3-positions of anthracenes on the diastereoselectivity (anti vs syn dimer) of the [π4s + π4s] photoinduced dimerization is investigated. The synthesis of the anthracene derivatives was achieved by Suzuki–Miyaura reaction of 2,3-dibromoanthracene with alkylboronic acids as well as by reduction of anthraquinones that were obtained from 2,3-disubstituted 1,3-butadienes and naphthoquinone followed by dehydrogenation. The mixtures of dianthracene isomers were analyzed with respect to the anti/syn-ratio of the products by X-ray crystallography and nuclear Overhauser effect spectroscopy. While for the 2,3-dimethylanthracene the anti and syn isomers were formed in equal amounts, the anti dimers are the major products in all other cases. A linear correlation (R 2 = 0.98) between the steric size (Charton parameter) and the isomeric ratio suggests that the selectivity is dominated by classical repulsive steric effects. An exception is the iso-butyl substituent that produces an increased amount of the syn isomer. It is suggested that this is due to an exalted effect of London dispersion interactions.

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“…[50] Synthetically attractive feature of silicon-based protecting groups is that a suitable choice of substituents on the silicon atom can modulate their susceptibility to acid-and base-catalyzed hydrolysis, while a convenient way for their cleavage can be provided by the lability of the silyl ethers in the presence of fluoride ion. [51][52][53][54][55][56][57][58][59][60] Known as a group of chemical compounds, silyl ethers contain a silicon atom covalently bonded to an alkoxy group. R 1 R 2 R 3 Si-O-R 4 can be regarded as the general structure where R 4 is an alkyl group or an aryl group.…”

Section: Introductionmentioning

confidence: 99%

Recent advances in catalytic silylation of hydroxyl‐bearing compounds: A green technique for protection of alcohols using Si–O bond formations

Ashraf

Liu

et al. 2020

Applied Organom Chemis

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The development of catalytic silylation of alcohols under ambient reaction conditions plays an important role in organic synthesis. New silyl groups and methods for their introduction and removal are constantly being developed and offer chemists a wider range of options. In recent years, silyl protecting groups have been given expanded roles beyond their traditional use of temporarily rendering inactive alcohols. As silyl ether can be further converted to the parent alcohols in acidic conditions, silylation of alcohols can be regarded as an alternative method for hydroxyl protection under ambient reaction conditions. Merging the silyl protection/deprotection of alcohols with such modern methodologies, as green chemistry and nanoscience, has added additional value to these temporary components of synthetic intermediates. This review describes the historical background of the trimethylsilyl ethers preparation from alcohols using catalytic complexes and also the transformation of trimethylsilyl ethers into alcohol-containing compounds via deprecation techniques.

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Substituent Effects in the Silylation of Secondary Alcohols: A Mechanistic Study

Cited by 22 publications

References 47 publications

Size-Driven Inversion of Selectivity in Esterification Reactions: Secondary Beat Primary Alcohols

Size-Driven Inversion of Selectivity in Esterification Reactions: Secondary Beat Primary Alcohols

Synthesis and Photodimerization of 2- and 2,3-Disubstituted Anthracenes: Influence of Steric Interactions and London Dispersion on Diastereoselectivity

Recent advances in catalytic silylation of hydroxyl‐bearing compounds: A green technique for protection of alcohols using Si–O bond formations

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