Reactivity of Oxiranes with Organolithium Reagents

Chemla, Fabrice; Vrancken, Emmanuel

doi:10.1002/9780470682531.pat0314

Cited by 2 publications

(2 citation statements)

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“…The ring strain in oxiranes makes them useful reagents for a wide variety of synthetic pathways under mild conditions. Their rich chemistry in the presence of organolithium reagents has been discussed in several excellent reviews. − Although the possibility of competition between α-lithiation and β-elimination in oxirane chemistry has been well-recognized, further evolution of the intermediates produced by these initial steps along the two pathways remain to be studied and motivates the present work.…”

Section: Introductionmentioning

confidence: 99%

Rearrangement Reactions of Lithiated Oxiranes

2013

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The first computational study of the rearrangement reactions of oxiranes initiated by lithium dialkylamides is presented. Aside from the well-known carbenoid insertion pathways, both β-elimination and α-lithiation have been suggested as the exclusive mechanism by which oxiranes react in the presence of organolithium bases. The products of the former are allyl alcohols (and, in some cases, dienes) and are ketones in the case of the latter. The computational studies reported in this work indicate that both mechanisms could be simultaneously operational. In particular, our work shows that the allyl alcohols from β-elimination are unlikely to undergo 1,3-hydrogen transfer to the vinyl alcohols and thus to the ketones, suggesting that ketones are formed through the opening of the oxirane ring after α-substitution. Elimination of LiOH from the lithiated allyl alcohol is found to result in the diene product. Low activation barriers for β-elimination are offered as the explanation for the few special cases where the allyl alcohol is the dominant or exclusive product. These findings are consistent with the product distributions observed in several experiments.

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Section: Introductionmentioning

confidence: 99%

Rearrangement Reactions of Lithiated Oxiranes

2013

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“…However, the nucleophilicity of the phosphazenyl-stabilized anion seems to be too low to achieve ring opening of the oxirane leading to intermediate species Li-IIa . 36 After some experimentation (including various temperatures, activation by CeCl 3 , etc. ), we found that performing the addition of the electrophile at –35 °C and then heating the reaction mixture at 45 °C for 2 h gave, after aqueous workup, the expected spiro-1,2-oxaphospholanone 17a isolated in a yield of 86% by precipitation from diethyl ether.…”

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confidence: 99%

Synthesis of Pentacoordinated Spiro[4.4]phosphoranes by Reaction of Cyclic Phosphazenyl Anions with Epoxides: Study of their P-Remote Functionalization and Hydrolysis

López¹,

Ortiz²,

Peraza³

et al. 2021

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The synthesis of a new family of pentacoordinated spiro[4,4]phosphoranes stabilized by the ortho-benzamide bidentate ligand (oBA,-C6H4-2-C(O)NH-) through reaction of Cα -Cortho-dilithiated phosphazenes with oxiranes is reported. Mixtures of epimers that differ in configuration at the phosphorus atom were obtained with moderate to high yields and diastereoselectivities. C3-disubstituted derivatives could be separated, which provided access to enantiopure products arising from the reaction with (R)-2-phenyloxirane. Stereomutation was observed by heating the spirophosphoranes at 100 ºC. Directed ortho lithiation of spirophoshoranes followed by electrophilic quench reactions including carbon-based and heteroatom-based electrophiles afforded derivatives functionalized in remote position with respect to the phosphorus atom. Benzoic acid catalyzed hydrolysis of spirophosphoranes furnished ortho-(hydroxyalkylphosphoryl)benzamides by cleavage of the P‒O and P‒N bonds with retention of the phosphorus configuration. In contrast, alkaline hydrolysis led to the formation of γ-hydroxyphosphinic acids and benzamide.

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Reactivity of Oxiranes with Organolithium Reagents

Abstract: General Introduction α‐/β‐Deprotonation β‐Deprotonation Oxirane Ring Opening by Organolithium Reagents Synthesis and Reactivity of Lithiooxiranes General Conclusion Acknowledgments

Cited by 2 publications

References 312 publications

Rearrangement Reactions of Lithiated Oxiranes

Rearrangement Reactions of Lithiated Oxiranes

Synthesis of Pentacoordinated Spiro[4.4]phosphoranes by Reaction of Cyclic Phosphazenyl Anions with Epoxides: Study of their P-Remote Functionalization and Hydrolysis

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