Enantiomerically pure γ-oxidofunctionalised organolithium compounds from chiral oxetanes

Bachki, Abderrazak; Falvello, Larry R.; Foubelo, Francisco; Yus, Miguel

doi:10.1016/s0957-4166(97)00274-7

Cited by 31 publications

(13 citation statements)

References 46 publications

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“…Dianionic species 152±154 were prepared by reductive opening of different heterocycles [83] by an arene-catalyzed lithiation and reacted with electrophiles to give polyfuncionalized molecules in good yields. Enantiomerically pure oxetanes [117,118] (for 152), 4-phenyl-1,3-dioxolanes [119] (for 153) and 2-phenyl-substituted azetidines or tietanes [120] (for 154) were the starting heterocycles used. The reductive cleavage always gave the most stable intermediate: the primary alkyllithium compounds for the chiral oxetanes and the benzylic derivatives for the other.…”

Section: C-functionalized Alkyllithium Compoundsmentioning

confidence: 99%

Polyfunctional Lithium Organometallics for Organic Synthesis

Yus¹,

Foubelo²

2005

Handbook of Functionalized Organometallics

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Multifunctional organic molecules can be achieved by reacting functionalized organolithium compounds [1] with electrophilic reagents, this fact makes these intermediates of relevant interest in synthetic organic chemistry [2]. Another remarkable fact concerning organolithium compounds, compared with other organometallic compounds is that they can be prepared following a great number of different methodologies [3]: hydrogen±lithium exchange (deprotonation), halogen±lithium exchange, transmetallation reactions, carbon±heteroatom bond cleavage and carbolithiation of multiple carbon±carbon bonds. However, the highly ionic character of the carbon±lithium bond [4] makes these compounds extremely reactive and also unstable, so the synthetic processes should be carried out in some cases under very mild reaction conditions.Regarding the stability of functionalized organolithium compounds, it depends mainly on three factors, the most important one being the compatibility of the functional group with the carbon±lithium bond, so in some cases the functionality should be protected. The hybridization of the carbon atom bonded to the lithium atom is also important, so sp derivatives are more stable than the corresponding sp 2 and these are more stable than the sp 3 ones as it happens to the corresponding carbanions. Finally, the relative position of the functionality and the carbanionic center is also relevant, probably the b-functionalized derivatives being the most unstable species due to the existence of two consecutive carbon atoms with opposite polarities, the b-elimination process to give an olefin is extremely favored. Stabilized organolithium compounds, such as lithium enolate intermediates [5], a-organolithium compounds bearing electron-withdrawing groups (RSO, RSO 2 , CN, NO 2 , etc.) and heteroatoms such as sulfur [6], selenium and phosphorus as well as functionalized aryllithium compounds will not be consider in depth in this chapter due to the limited length of this review.The following study is ordered based on the relative position of the functionality and the carbanionic center, as well as on the hybridization of that center.

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Section: C-functionalized Alkyllithium Compoundsmentioning

confidence: 99%

Polyfunctional Lithium Organometallics for Organic Synthesis

Yus¹,

Foubelo²

2005

Handbook of Functionalized Organometallics

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“…This regiochemistry in the case of oxiranes can be explained by the greater stability of the more-substituted alkoxide, which outweighs the lower stability of the less-substituted radical that is formed by the rupture of the intermediate oxirane radical anion. [69] Scheme 9 [13] γ-Lithioalkoxides can provide 2-substituted tetrahydrofurans upon trapping with aldehydes and ketones followed by acid cyclisation of the resulting 1,4-diols; the cuprates of these dianions undergo conjugate addition and nucleophilic substitution reactions.…”

Section: Ring Opening Of Oxiranes and Oxetanesmentioning

confidence: 99%

“…[66] The lithiation of chiral oxetanes in the presence of a catalytic amount of DTBB in tetrahydrofuran at Ϫ78°C leads to γ-lithioalkoxides which, in the reaction with different electrophiles (E ϩ ), afford the expected functionalised alcohols after hydrolysis with water (Scheme 9). [69] Scheme 9…”

Section: Ring Opening Of Oxiranes and Oxetanesmentioning

confidence: 99%

Chemical Methods for Ether‐Bond Cleavage by Electron‐Transfer Reagents

Grobelny

2004

Eur J Org Chem

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Ethers can easily be cleaved with various electron‐transfer reagents. New data concerning the chemical methods of the regioselective opening of the ether bond with alkali metals (M0), alkali metal aromatic radical anions (Ar·−, M+), alkalides (M−, M+C; C denotes a ligand) and low‐valent transition‐metal compounds are presented. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

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“…In this manner conjugate addition reactions were carried out and spiroketals and oxaspirolactones were prepared (Scheme ). Many enantiomerically pure compounds of interest for the preparation of biologically active compounds could also be synthesized, although usually with low selectivities 72…”

Section: Reductive Cleavage Of Heterocycles By Electron Transfer Fmentioning

confidence: 99%

Strained Heterocycles in Radical Chemistry

2003

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Over the last few decades the use of radicals in synthesis has witnessed an explosive growth through introduction of efficient chain and electron-transfer reactions. Strained heterocycles, in particular, have emerged as a highly versatile and readily available class of radical precursors. The generation of carbinyl radicals of heterocycles has resulted in many elegant applications of heteroatom-centered radicals, such as beta fragmentations, cyclizations, and intramolecular hydrogen atom abstractions. Direct electron transfer to strained heterocycles has been realized through the use of arene radical anions. The method combines the virtues of radical and organometallic chemistry to yield useful functionalized organolithium compounds. Epoxides have been opened with high regioselectivity by titanocene(III) reagents in either stoichiometric or catalytic quantities to yield beta-titanoxy radicals. This development has resulted in many new applications in natural product synthesis.

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Enantiomerically pure γ-oxidofunctionalised organolithium compounds from chiral oxetanes

Cited by 31 publications

References 46 publications

Polyfunctional Lithium Organometallics for Organic Synthesis

Polyfunctional Lithium Organometallics for Organic Synthesis

Chemical Methods for Ether‐Bond Cleavage by Electron‐Transfer Reagents

Strained Heterocycles in Radical Chemistry

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