Stereoselective Lateral Functionalization of Monosubstituted [2.2]Paracyclophanes by Directedortho-Metalation−Homologous Anionic Fries Rearrangement

Focken, Thilo; Hopf, Henning; Snieckus, Victor; Dix, Ina; Jones, Peter G.

doi:10.1002/1099-0690(200106)2001:12<2221::aid-ejoc2221>3.0.co;2-3

Cited by 26 publications

(8 citation statements)

References 15 publications

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“…Of these, 14 were pure enantiomers; for 12 of these, the absolute configuration was determined. Of the remaining six, five were not organic compounds [two metal complexes with Z = 1 (Jones et al, 1996;Filimon et al, 2014), two organotellurium compounds (Jones et al, 2015, Z = 1; du Mont et al, 2010, Z = 4), and one phosphane sulfide (Taouss & Jones, 2013, Z = 2)], and the remaining structure (Focken et al, 2001, Z = 4) displayed planar chirality, but contained no 'asymmetric' atom. On this limited basis, we would therefore postulate that is very rare for achiral organic compounds to crystallize in P1, especially with Z = 1.…”

Section: Database Surveymentioning

confidence: 99%

Crystal structure of N′-[2-(benzo[d]thiazol-2-yl)acetyl]benzohydrazide, an achiral compound crystallizing in space group P1 with Z = 1

Azzam¹,

Elgemeie²,

Seif³

et al. 2021

Acta Crystallogr E Cryst Commun

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In the molecule of the title compound, C16H13N3O2S, one hydrazinic nitrogen atom is essentially planar, but the other is slightly pyramidalized. The torsion angle about the hydrazinic bond is 66.44 (15)°. Both hydrazinic hydrogen atoms lie antiperiplanar to the oxygen of the adjacent carbonyl group. The molecular packing is a layer structure determined by two classical hydrogen bonds, N—H...O=C and N—H...Nthiazole. The space group is P1 with Z = 1, which is unusual for an achiral organic compound.

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Section: Database Surveymentioning

confidence: 99%

Crystal structure of N′-[2-(benzo[d]thiazol-2-yl)acetyl]benzohydrazide, an achiral compound crystallizing in space group P1 with Z = 1

Azzam¹,

Elgemeie²,

Seif³

et al. 2021

Acta Crystallogr E Cryst Commun

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“…Functionalisation of C2 is rare; Hou, 24 Pelter, 38 and Bolm 39 have all described the accidental/nonselective deprotonation of C2, but only Hopf has achieved deliberate 'lateral' functionalisation. 40 Treatment of diastereoisomer (S p ,R S )-9 with lithium diisopropylamide (LDA) and MeI furnished a new compound 23 (16%) along with starting material (Scheme 6). Reaction of (R p ,S S )-9 with an alternative electrophile, diphe- nylphosphinic chloride, resulted in two new products, sulfoxide 24 (53%) and sulfide 25 (10%), as well as starting material (18%; Scheme 7).…”

Section: Figure 1 Common [22]paracyclophane Derivativesmentioning

confidence: 99%

Towards a Flexible Strategy for the Synthesis of Enantiomerically Pure [2.2]Paracyclophane Derivatives: The Chemistry of 4-Tolylsulfinyl[2.2]paracyclophane

Parmar¹,

Coles²,

Hitchcock³

et al. 2010

Synthesis

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The use of enantiomerically enriched 4-tolylsulfinyl[2.2]paracyclophane as a precursor to a variety of mono-and disubstituted [2.2]paracyclophane derivatives is described. The goal of our research is to develop a single general precursor that permits the synthesis of the most common [2.2]paracyclophane substitution patterns. The chemistry of two diastereoisomers of 4-tolylsulfinyl[2.2]paracyclophane has been explored and it facilitates the synthesis of enantiomerically enriched 4-substituted and 4,13disubstituted [2.2]paracyclophanes. Directed lithiations result in an unusual cyclisation reaction. Whilst the tolyl group cannot realise our goal, the chemistry outlined acts as a successful 'proof of concept.'

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“…Not only alkyl groups, but also aryl [492,493], vinyl [494], acyl [276,[495][496][497], alkoxycarbonyl [498], aminocarbonyl [499][500][501], silyl [502][503][504], or phosphoryl groups [279,280] can migrate to a vicinal carbanion (Scheme 5.68). Because some of these groups can be used to stabilize a-heteroatom-substituted carbanions by chelate formation, migration of these groups to the carbanion is a potential side reaction in the generation and alkylation of chelate-stabilized carbanions.…”

Section: Rearrangementmentioning

confidence: 99%

The Alkylation of Carbanions

Dörwald

2004

Side Reactions in Organic Synthesis

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The deprotonation of organic compounds by strong, non-nucleophilic bases followed by C-alkylation with a suitable electrophile has become one of the most predictable and straightforward methods for formation of C-C bonds. The popularity of this chemistry is also a consequence of the often-seen close resemblance of feasible structural modifications by a deprotonation/alkylation strategy to an unsophisticated retrosynthetic analysis of a given target compound. Other reactions, which involve, for instance, substantial rearrangement of the carbon framework (e.g. Cope rearrangement, fragmentations, ring contractions or enlargements) are usually more difficult to take into account during retrosynthetic analysis.LDA and related, sterically hindered, lithium dialkylamides, first investigated by Levine [1], have completely replaced the more nucleophilic sodium amide, which had been the base of choice for many years [2]. Because the reactivity of an organometallic compound depends to a large extent on its state of aggregation (i.e. on the solvent and on additives) and on the metal, transmetalation of the lithiated intermediates and the choice of different solvents and additives emerged as powerful strategies for fine-tuning the reactivity of these valuable nucleophiles.In this chapter the alkylation of carbanions with simple carbon electrophiles will be discussed, with special emphasis on the structure-reactivity relationship of the carbanion and on side reactions. In this context the term "carbanion" refers to an intermediate prepared by in-situ deprotonation of an organic compound, followed by optional cation exchange (transmetalation), which tends to be alkylated at carbon by soft electrophiles such as MeI or PhCHO. This type of reactivity is characteristic of enolates with an ionic M-O bond or for organometallic compounds with a strongly polarized or ionic M-C bond, M typically being an alkali metal, Mg, Cu, or Zn. Carbanions can, alternatively, also be prepared by halogen-metal exchange [3-8], sulfoxide-or sulfone-metal exchange [9-13], or by transmetalation of stannanes. The most suitable reagents for performing such metalating exchange reactions are organometallic compounds with a metal-bound secondary or tertiary alkyl group, such as tBuLi, sBuLi, iPr 2 Zn [14, 15], or iPrMgHal [6]. These reagents are thermodynamically less stable than organometallic compounds with primary alkyl 5 146 Scheme 5.1. Approximate relative rates of proton transfer in water at thermoneutrality (DpK a = 0) [35, 39, 51]. 147 Scheme 5.2. The effect of fluorine on the acidity of organic compounds [24, 62-65]. 148 Scheme 5.3. Dependence of the reactivity of carbanions on their basicity [68, 72-74]. Regioselectivity of Deprotonations and AlkylationsThe organic chemist is occasionally confronted with the problem that a compound has several differrent X-H groups of similar pK a . If only one of these is to be alkylated, one option would be to perform a regioselective deprotonation. This can sometimes be achieved by exploiting small differences be...

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Stereoselective Lateral Functionalization of Monosubstituted [2.2]Paracyclophanes by Directedortho-Metalation−Homologous Anionic Fries Rearrangement

Cited by 26 publications

References 15 publications

Crystal structure of N′-[2-(benzo[d]thiazol-2-yl)acetyl]benzohydrazide, an achiral compound crystallizing in space group P1 with Z = 1

Crystal structure of N′-[2-(benzo[d]thiazol-2-yl)acetyl]benzohydrazide, an achiral compound crystallizing in space group P1 with Z = 1

Towards a Flexible Strategy for the Synthesis of Enantiomerically Pure [2.2]Paracyclophane Derivatives: The Chemistry of 4-Tolylsulfinyl[2.2]paracyclophane

The Alkylation of Carbanions

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