Rapid and Easy Access to (<i>E</i>)‐1,3‐Enynes, 1,3‐Diynes and Allenes Starting from Propargylic Acetals, Exploiting the Different Reactivity of Lithium and Mixed Lithium–Potassium Organometallic Reagents

Blangetti, Marco; Deagostino, Annamaria; Rosso, Helèna; Prandi, Cristina; Zavattaro, Chiara; Venturello, Paolo

doi:10.1002/ejoc.200700520

Cited by 5 publications

(4 citation statements)

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“…In the presence of an excess of reagent, α-phenyl acetals undergo 1,2-elimination followed by vinylic α-metalation to afford, after electrophilic trapping, the corresponding vinyl ethers. Propargyl alcohols can be synthesized from the latter by further treatment with LIS-KOR or from the α-phenyl acetals using an excess of base (Table ). ,, The method has since been extended to propargylic acetals to give either 1,3-diynes or allenes, depending on the amount of base employed (Scheme ) …”

Section: Reactions Of Maas Involving Base Ligand Transfer Processes (...mentioning

confidence: 99%

“…766c,e, 769 The method has since been extended to propargylic acetals to give either 1,3-diynes or allenes, depending on the amount of base employed (Scheme 183). 770 In 1998, Caub ere and co-workers compared reagents prepared from Me 2 N(CH 2 ) 2 OH, NaH, and BuLi, on the one hand, and Me 2 N(CH 2 ) 2 OH, H 2 NNa, and BuLi, on the other hand, for their ability to metalate 2-methoxypyridine. They observed that the former, assumed to be BuLi 3 DMAENa, reacts at the 6-position of 2-methoxypyridine, whereas the latter, supposed to be the same reagent in the presence of NH 3 , abstracts the proton from the 3-position.…”

Section: Reactions Of Maas Involving Base Ligand Transfer Processes (...mentioning

confidence: 99%

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Mixed AggregAte (MAA): A Single Concept for All Dipolar Organometallic Aggregates. 2. Syntheses and Reactivities of Homo/HeteroMAAs

2013

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6. Conclusion 7706 Author Information 7706 Biographies 7707 Acknowledgment 7707 Abbreviations Used 7707 References 7708the corresponding allyl-and propargylchromium reagents that further react with a variety of electrophiles to afford the corresponding adducts in high yields. 102 Bu 6 CrLi 3 similarly behaves as a formal two-electron reductant with ketones and esters bearing a leaving group at the α-position to produce enolates that are intercepted with a variety of electrophiles with high selectivities (Table 8). 103 Such enolates are also capable of reacting with oxiranes to afford γand β-hydroxy esters, depending on the Lewis acid used as promoter. 2143.2.2. Two-Electron Transfers from M,Mn-HeteroMAAs (M = Li, MgX). In 1976, Cahiez et al. disclosed the possible reduction in THF of alkenyl bromides or iodides, as well as aryl chlorides or bromides, using i-PrMgCl in the presence of a catalytic amount of MnCl 2 . 215 The authors proposed the in situ formation of unstable i-Pr 3 MnMgCl and its decomposition by β-elimination to H 3 MnMgCl; reaction of the latter with the halide would then afford an unstable Mn(IV) intermediate, able Scheme 23 Scheme 24 Scheme 21 Scheme 22

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Section: Reactions Of Maas Involving Base Ligand Transfer Processes (...mentioning

confidence: 99%

Section: Reactions Of Maas Involving Base Ligand Transfer Processes (...mentioning

confidence: 99%

Mixed AggregAte (MAA): A Single Concept for All Dipolar Organometallic Aggregates. 2. Syntheses and Reactivities of Homo/HeteroMAAs

2013

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“…In order to functionalize tetraphenylcyclopentadienones with a polar pending chain to obtain 1a and 1b, 2a has been at first reacted with 2-methyl-3butyn-2-ol (5a) or 1,1-diphenyl-2-propyn-1-ol (5b) under Sonogashira coupling reaction conditions in THF at reflux. Unfortunately, these reactions gave 1a and 1b only in traces, selectively leading to an almost quantitative formation of 2,7-dimethylocta-3,5-diyne-2,7-diol 23 and 1,1,6,6-tetraphenylhexa-2,4-diyne-1,6-diol, 24 respectively, both derived from the homocoupling between the two propargyl alcohols 5a or 5b. This problem has been overcome by functionalizing the precursor 4,4 0 -dibromobenzil (3) through the Sonogashira coupling with the desired alkynyl alcohols 5a and 5b.…”

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confidence: 99%

A new tetraarylcyclopentadienone based low molecular weight gelator: synthesis, self-assembly properties and anion recognition

et al. 2012

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“…Propargylic acetals proved to be versatile substrates for the synthesis of 1,3-or 1,2-unsaturated systems. 17 The general reactivity depicted in Scheme 16 could be selectively oriented to the target compounds (enynes, diynes or allenes) by the choice of a suitable base, so that functionalized E-conjugated enynes can be obtained in the presence of LDA, while an excess (3.4 equiv) of superbase LIC-KOR 4 (BuLi/t-BuOK, 1/1) selectively promotes the synthesis diynes 61. Moreover, a carefully control of the reaction temperature allows the isolation of allenes 57.…”

Section: Applicationsmentioning

confidence: 99%

1,3- and 1,2-Unsaturated Derivatives as Valuable Synthetic Tools in Organometallic Syntheses

Deagostino¹,

Prandi²,

Tabasso³

et al. 2010

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This review gives an overview of our recent developments in the chemistry of 1,3-and 1,2butadiene derivatives, with a special attention to their use in palladium catalyzed reactions. The reactions of α,β-unsaturated and propargylic acetals with various lithium and mixed lithiumpotassium Schlosser reagents will be firstly reviewed. These processes have afforded (E)-1-alkoxy-1,3-dienes, and (E)-1,3-enynes, 1,3-diynes or allenes, respectively. When the reactions have been carried out in the presence of suitable electrophiles a linear route to functionalized derivatives has been set up. The above-mentioned compounds can be thus considered valuable synthetic tools for the construction of various and more complex structures and, in particular, they have been established to be useful reagents for the Suzuki-Miyaura cross-coupling reaction. As a matter of fact, alkoxy-functionalized butadienylboronic esters have been synthesized, cross-coupled with both N-protected and N-unprotected haloanilines (or halophenols), and finally transformed under mild conditions into quinolines and quinolinones (or chromenes and chromenones). The second part of the paper will deal with our recent interest in the Heck coupling of conjugate systems. In particular, the synthesis of γ-arylated α,β-unsaturated carbonyl compounds, by regioselective Heck process on 1-alkoxy-1,3-dienes in ionic liquids will be reviewed, in conjunction with the Heck coupling of 1,2dien-1-ols to α-arylated α,β-unsaturated aldehydes. A survey of the recent literature on closely related topics will complete the contribution.

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Rapid and Easy Access to (E)‐1,3‐Enynes, 1,3‐Diynes and Allenes Starting from Propargylic Acetals, Exploiting the Different Reactivity of Lithium and Mixed Lithium–Potassium Organometallic Reagents

Cited by 5 publications

References 38 publications

Mixed AggregAte (MAA): A Single Concept for All Dipolar Organometallic Aggregates. 2. Syntheses and Reactivities of Homo/HeteroMAAs

Mixed AggregAte (MAA): A Single Concept for All Dipolar Organometallic Aggregates. 2. Syntheses and Reactivities of Homo/HeteroMAAs

A new tetraarylcyclopentadienone based low molecular weight gelator: synthesis, self-assembly properties and anion recognition

1,3- and 1,2-Unsaturated Derivatives as Valuable Synthetic Tools in Organometallic Syntheses

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