Direct Metal‐Free Entry to Aminocyclobutenes or Aminocyclobutenols from Ynamides: Synthetic Applications

Alcaide, Benito; Almendros, Pedro; Lázaro‐Milla, Carlos

doi:10.1002/chem.201601044

Cited by 30 publications

(12 citation statements)

References 57 publications

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“…Sterically less‐hindered alkynyldiphenylphoshines were also converted into the desired products ( 5 l – 5 o ), with aryl, alkyl, and trialkylsilyl substituents on the C(sp) atom. Notably, in these cases, the [2+2] cycloaddition products were not formed ,. In contrast, in‐situ‐generated compound 4 did not form any adducts during the reactions with some sulfides.…”

Section: Resultsmentioning

confidence: 87%

Synthesis and Characterization of Stable Phosphorus Carbabetaines

Yanai

Almendros

Takahashi

et al. 2018

Chemistry An Asian Journal

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Phosphorus 1,3- and 1,4-carbabetaines with 'P(+)-C-C(-)' and 'P(+)-C-C-C(-)' structures, respectively, in which the carbanion moiety was significantly stabilized by two trifluoromethylsulfonyl groups, have been synthesized and characterized. Analysis of their X-ray crystal structures revealed that any attractive interactions between the anionic and cationic moieties were negligibly weak. This result was corroborated by using natural bond orbital (NBO) and Bader's quantum theory of atoms in molecules (QTAIM) models. In contrast, performing the same analysis of a known 1,3-carbabetaine equivalent, which can be drawn as a 'P(+)-C-C=C-O(-)' resonance structure, revealed pronounced charge-transfer interactions between the anionic and cationic moieties.

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Section: Resultsmentioning

confidence: 87%

Synthesis and Characterization of Stable Phosphorus Carbabetaines

Yanai

Almendros

Takahashi

et al. 2018

Chemistry An Asian Journal

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“…Finally, N -substituted and 5-substitiuted sulfonamidoindoles ( 1b and 1e ) also afforded 4ba and 4ea in decent yields (76% and 65%) with 2a . It is known that Cs 2 CO 3 has fair solubility in many organic solvents and quite low solubility in toluene, but the dramatic effect of tosyl group transfer as observed here is rather unexpected …”

Section: Resultsmentioning

confidence: 99%

“…In this A1 undergoes a second addition–elimination process with 1a′ to give the allenic intermediate B3 . Intermediate B3 is involved in the aza-Claisen rearrangement , to give zwitterionic intermediate B4 . Finally, tosyl group elimination/readdition, and aromatization involving species B4 – B7 are expected to be involved in the formation of the unexpected α-carboline with a tosyl functionality at the γ-carbon 4aa .…”

Section: Resultsmentioning

confidence: 99%

Divergent Reactivity of δ- and β′-Acetoxy Allenoates with 2-Sulfonamidoindoles via Phosphine Catalysis: Entry to Dihydro-α-carboline, α-Carboline, and Spiro-cyclopentene Motifs

et al. 2021

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The reactivity of 2-sulfonamidoindoles with acetoxy allenoates under phosphine catalysis depends on the disposition of the acetoxy (OAc) group on the allenoate. In the temperature-controlled [3 + 3] annulations, δ-acetoxy allenoates afforded dihydrocarboline and carboline scaffolds with carbon−nitrogen nucleophilic 2-sulfonamidoindoles, in which allenoate serves as a β-, γ-, and δ-carbon donor. At room temperature (25 °C), dihydro-α-carboline motifs were obtained exclusively through Michael addition, 1,4-proton shift, isomerization, 1,2-proton transfer, phosphine elimination, and aza-Michael addition. The higher temperature (80 °C) cascade protocol using Ph 3 P−Cs 2 CO 3 combination involves addition−elimination, aza-Claisen rearrangement, tosyl migration, and aromatization as key steps to give α-carbolines containing tosyl functionality at the γ-carbon. In contrast, with β′acetoxy allenoate, 2-sulfonamidoindole acts only as a carbo-nucleophile in (p-tolyl) 3 P-directed [4 + 1] spiro-annulation, leading to five-membered spiro-carbocyclic motifs essentially as single diastereomers (dr >20:1) via chemoselective carbo-annulation.

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“…In 2013, Clavier and Buono published a [2 + 1] cycloaddition of N -alkynyl amides and azoles with norbornene (Scheme 61) [93]. The researchers were interested in developing a new method for synthesizing aminomethylenecyclopropanes, a structure found in powerful antiviral agents, but with limited methods for its synthesis [94]. Ultimately Clavier and Buono found two sets of conditions ( A/B ) that successfully added N -alkynyl amides/azoles to norbornene.…”

Section: Reactions Of N-alkynyl Azolesmentioning

confidence: 99%

Preparation and Utility of N-Alkynyl Azoles in Synthesis

Reinus

Kerwin

2019

Molecules

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Heteroatom-substituted alkynes have attracted a significant amount of interest in the synthetic community due to the polarized nature of these alkynes and their utility in a wide range of reactions. One specific class of heteroatom-substituted alkynes combines this utility with the presence of an azole moiety. These N-alkynyl azoles have been known for nearly 50 years, but recently there has been a tremendous increase in the number of reports detailing the synthesis and utility of this class of compound. While much of the chemistry of N-alkynyl azoles mirrors that of the more extensively studied N-alkynyl amides (ynamides), there are notable exceptions. In addition, as azoles are extremely common in natural products and pharmaceuticals, these N-alkynyl azoles have high potential for accessing biologically important compounds. In this review, the literature reports of N-alkynyl azole synthesis, reactions, and uses have been assembled. Collectively, these reports demonstrate the growth in this area and the promise of exploiting N-alkynyl azoles in synthesis.

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Direct Metal‐Free Entry to Aminocyclobutenes or Aminocyclobutenols from Ynamides: Synthetic Applications

Cited by 30 publications

References 57 publications

Synthesis and Characterization of Stable Phosphorus Carbabetaines

Synthesis and Characterization of Stable Phosphorus Carbabetaines

Divergent Reactivity of δ- and β′-Acetoxy Allenoates with 2-Sulfonamidoindoles via Phosphine Catalysis: Entry to Dihydro-α-carboline, α-Carboline, and Spiro-cyclopentene Motifs

Preparation and Utility of N-Alkynyl Azoles in Synthesis

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