Sulfoximine‐Directed Single and Double ortho‐Lithiation: Stereoselective Rearrangements of o,o′‐Dilithiophenylsulfoximines to o,N‐Dilithiosulfinylanilines through Anionic Fries Rearrangements of o,o′‐Dilithiophenylsulfinamides

Wessels, Michael; Mahajan, Vishal A.; Bosshammer, S.; Raabe, Gerhard; Gais, Hans‐Joachim

doi:10.1002/ejoc.201100066

Cited by 31 publications

(20 citation statements)

References 77 publications

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“…The sulfoximine unit in 4 is an excellent ortho-director of lithiation. 4,6 This is seen on addition of butyl lithium to sulfoximine 4 which apparently leads to formation of the o-lithio derivative.…”

Section: Resultsmentioning

confidence: 99%

“…But having o-silyl compound 5 in hand, an iododesilylation 7 approach to 6 seemed to offer an attractive alternative (Scheme 2). However, when 5 is treated with iodine chloride, the product is not the expected iodide 6, but a totally different type of product which was identified as the 3H-1λ 6 : S1-O10 1.451, S1-N2 1.512, S1-C9 1.792, S1-C11 1.828, Si3-N2 1.721, Si3-C8 1.886.…”

Section: Resultsmentioning

confidence: 99%

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An unexpected cyclization reaction of tert-butyl o-trimethylsilylphenyl sulfoximine

Schmidt¹,

Adiwidjaja²,

Schaumann³

2012

Arkivoc

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

An unexpected cyclization reaction of tert-butyl o-trimethylsilylphenyl sulfoximine

Schmidt¹,

Adiwidjaja²,

Schaumann³

2012

Arkivoc

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“…In contrast, α‐branched sulfones lacking the additional γ‐branching deprotonated as usual in the α‐position, leading directly to III . The Gais group found a similar DoM/transmetalation behavior for conformationally constrained sulfoximines 5…”

Section: Introductionmentioning

confidence: 85%

“…On the other hand, two consecutive proton transfers may first lead to an ortho ,α‐dilithium intermediate VIII and substrate IV as the rate‐limiting step, from which a second, potentially fast proton transfer follows, leading to two units of IX . Indeed, intermediates VIII were previously individually generated by Gais and colleagues by a reverse strategy of initial α‐ and subsequent ortho ‐metalation 5,7…”

Section: Introductionmentioning

confidence: 99%

Elucidation of the Reaction Mechanism of ortho→α Transmetalation Reactions of Alkyl Aryl Sulfone Carbanions

Řehová

Jahn

2014

Eur J Org Chem

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The sulfonyl group, as an electron‐accepting function, displays a strong acidifying effect on neighboring α‐hydrogen atoms, leading to their deprotonation by bases. Recently, reversal of the metalation selectivity of α,γ‐branched alkyl aryl sulfones was described, which instead undergo directed ortho‐metalation with good regioselectivity, despite having a more acidic α‐proton. Upon warming, a transmetalation to the α‐carbanion proceeds; however, nothing is known about the course of this transmetalation. Here, a mechanistic study is presented that sheds light on the facility of the initial metalation and the subsequent transmetalation. Large kinetic isotope effects were observed for both the initial deprotonation and the ortho→α transmetalation, which strongly influence the initial metalation selectivity. The results of a kinetic investigation of the transmetalation and a crossover study indicate that a concerted intermolecular pathway, either from an aggregate or from a monomeric aryllithium, prevails. The potential involvement of a stepwise process via ortho,α‐dilithium intermediates was investigated, but no hint of their involvement was found.

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“…(1) n-BuLi, −78°C More recently, Gais and coworkers [153] have used cyclic alkylsulfoximines for evaluating the selectivity of ortho-versus α-metalation. They found that lithiation in ortho-position was favored at low temperature (−50 • C), whereas the proportion of the α-metalated product becomes larger (even quantitative) by increasing the temperature.…”

Section: Sulfoximinesmentioning

confidence: 99%

Sulfur‐Bearing Lithium Compounds in Modern Synthesis

Ruano

Parra

Alemán

2014

Lithium Compounds in Organic Synthesis

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Sulfur functions have been widely used for the stabilization of lithium carbanions. Their different oxidation states determine a variety of mechanisms for such stabilization, mainly related with their electronic effects (−I and −M) and associative abilities and also with the relative position of sulfur with respect to the C-Li bond. As additional interest, the sulfur of some of these functions is a stable stereogenic center, and their interactions with prochiral lithium carbanions are able to control the stereochemical course of their reactions with electrophiles, which can be successfully used in asymmetric synthesis. Finally, the chemical versatility of the sulfur functions and their easy elimination under diverse conditions confer to the sulfur-stabilized lithium carbanions a very important role in modern synthetic chemistry. In this chapter, we have organized the information attending to the relative position of the carbanionic center with respect to the sulfur function (α-, β-, and γ-lithiation, see Figure 8.1). Each item has been subdivided according to the nature of the sulfur function stabilizing the carbanion. In this sense, sulfoxides, sulfones, and sulfoximines are the three main functions stabilizing any type of lithium-carbanions, but the thioethers have also been described as stabilizing in αand β-lithiation processes. The fragment connecting S and Li is always formed by carbon atoms, but N is present in some cases of γ-lithiation.This chapter covers the literature of the last 10-12 years concerning the preparation and main synthetic applications of the lithium carbanions stabilized by sulfur functions. In most of the cases, the information that appeared in this century helps understand the role of the sulfur functions in the stabilization of the lithium carbanions, and therefore we have only mentioned, as introduction, the seminal references in the field. However, in those cases where there are few references in the last decade and most of the information has been reported before 2000, we have included and briefly commented on the most significant contributions to be able to understand the interest of such stabilizing functions. During the last decade have appeared excellent revisions concerning the reactivity and structure of lithium carbanions [1], the use of different sulfur functions in asymmetric synthesis [2], as Lithium Compounds in Organic Synthesis: From Fundamentals to Applications, First Edition. Edited by Renzo Luisi and Vito Capriati.

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Sulfoximine‐Directed Single and Double ortho‐Lithiation: Stereoselective Rearrangements of o,o′‐Dilithiophenylsulfoximines to o,N‐Dilithiosulfinylanilines through Anionic Fries Rearrangements of o,o′‐Dilithiophenylsulfinamides

Cited by 31 publications

References 77 publications

An unexpected cyclization reaction of tert-butyl o-trimethylsilylphenyl sulfoximine

An unexpected cyclization reaction of tert-butyl o-trimethylsilylphenyl sulfoximine

Elucidation of the Reaction Mechanism of ortho→α Transmetalation Reactions of Alkyl Aryl Sulfone Carbanions

Sulfur‐Bearing Lithium Compounds in Modern Synthesis

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