Applications of the thermal ene reaction of aldehyde -butyl- and phenyl- hydrazones

Baldwin, Jack E.; Adlington, Robert M.; Jain, Ashok U.; Kolhe, Jayant N.; Perry, Matthew W. D.

doi:10.1016/s0040-4020(01)87649-3

Cited by 31 publications

(10 citation statements)

References 8 publications

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“…Ethyl benzoate (3ba), ethyl cinnamate (3ca), ethyl levulinate (3ja), ethyl 3-hexenoate (3la) and methyl 3-phenylpropanoate (3ac) are commercial products and the synthetic materials were compared with authentic samples. Ethyl 3-phenylpropanoate (3aa), 27 ethyl 4- 32 ethyl 10hydroxydecanoate (3ra), 33 tert-butyl 3-phenylpropanoate (3ab), 34 tert-butyl 3-hexenoate (3lb), 35 tert-butyl methyl glutarate (3ob), 36 tert-butyl hexanoate (3gb), 37 tert-butyl hippurate (3sb) 37 and methyl levulinate (3jc) 38 are known compounds and the spectra of the synthetic materials were superimposable with reported spectra. Table 3.…”

Section: -Phenylpropionic Anhydride (6a)mentioning

confidence: 99%

Reaction of Dicarbonates with Carboxylic Acids Catalyzed by Weak Lewis Acids: General Method for the Synthesis of Anhydrides and Esters

Bartoli¹,

Bosco²,

Carlone³

et al. 2007

Synthesis

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The reaction between carboxylic acids (RCOOH) and dialkyl dicarbonates [(R 1 OCO) 2 O], in the presence of a weak Lewis acid such as magnesium chloride and the corresponding alcohol (R 1 OH) as the solvent, leads to the esters RCOOR 1 in excellent yields. The mechanism involves a double addition of the acid to the dicarbonate, affording a carboxylic anhydride [(RCO) 2 O], R 1 OH and carbon dioxide. The esters arise from the attack of the alcohols on the anhydrides. Exploiting the lesser reactivity of tert-butyl alcohol in comparison with other alcohols, a clean synthesis of both carboxylic anhydrides and esters has been set up. In the former reaction, an acid/Boc 2 O molecular ratio of 2:1 leads to the anhydride in good to excellent yields, depending on the stability of the resulting anhydride to the usual workup conditions. In the latter reaction, stoichiometric mixtures of the acid and Boc 2 O are allowed to react with a twofold excess of a primary alcohol, secondary alcohol or phenol (R 2 OH) to give the corresponding esters (RCOOR 2 ). Purification of the products is particularly easy since all byproducts are volatile or water soluble. A very easy chromatography is required only in the case of nonvolatile alcohols. A broad variety of sensitive functional groups is tolerated on both the acid and the alcohol, in particular a high chemoselectivity is observed. In fact, no transesterification processes occur with the acid-sensitive acetoxy group and methyl esters.

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Section: -Phenylpropionic Anhydride (6a)mentioning

confidence: 99%

Reaction of Dicarbonates with Carboxylic Acids Catalyzed by Weak Lewis Acids: General Method for the Synthesis of Anhydrides and Esters

Bartoli¹,

Bosco²,

Carlone³

et al. 2007

Synthesis

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“…Related, albeit less complex amino acids, like lanthionine or diaminoglutamic acid either contain only four functional groups instead of five, as in the present case of labionin, or are not protected orthogonally8, 12, 13. Additionally the high density of functionalities easily leads to mostly undesired and disturbing intramolecular ring closing reactions14–16. Hence, lactam and lactone formations could be observed, when inadequate strategies were applied.…”

Section: Resultsmentioning

confidence: 95%

Synthetic studies toward labionin, a new α,α‐disubstituted amino acid from type III lantibiotic labyrinthopeptin A2

Sambeth

Süssmuth

2011

Journal of Peptide Science

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The labyrinthopeptins are a new class of lantibiotics containing two identical quaternary α,α-disubstituted amino acids, named labionin (Lab). The synthetic formation of this unique structural feature represents the key step in the total synthesis of these polycyclic peptides. In this report we describe the synthesis of an orthogonally protected α,α-disubstituted amino acid building block serving as labionin precursor for the future assembly of labyrinthopeptin A2 and of other labyrinthopeptin derivatives.

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“…Communications was incorporated at the terminal nitrogen to suppress Nalkylation, [14] while the 4-nitrophenyl group is intended to favor C-nucleophilic addition of the hydrazone.T he reaction of 1a with N-Boc imine 2a was performed in the presence of different CPAs (Figure 1) [15] with various solvents,t emperature,and concentrations.T he key results are summarized in Table 1. ForCPA sderived from BINOL, [16] the diastereo-and enantioselectivity were highly dependent on the nature of the C3 and C3' substituents (entries 2, 6-11).…”

Section: Angewandte Chemiementioning

confidence: 99%

Organocatalytic Nucleophilic Addition of Hydrazones to Imines: Synthesis of Enantioenriched Vicinal Diamines

Wang

Zhu

2017

Angew Chem Int Ed

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In the presence of a catalytic amount of chiral phosphoric acid, nucleophilic addition of N-monosubstituted hydrazones to N-Boc imines affords differentially protected vicinal diamines in the form of β-amino N,N'-dialkyldiazenes in excellent yields with high chemo-, diastereo-, and enantioselectivity. This catalytic asymmetric aza-Mannich reaction represents the first example in which N-alkyl hydrazones serve as α-azo carbanion equivalents to provide vicinal diamines with control of the two contiguous stereocenters. The adducts are readily converted into the monoprotected or free diamines and derivatives thereof.

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Applications of the thermal ene reaction of aldehyde -butyl- and phenyl- hydrazones

Cited by 31 publications

References 8 publications

Reaction of Dicarbonates with Carboxylic Acids Catalyzed by Weak Lewis Acids: General Method for the Synthesis of Anhydrides and Esters

Reaction of Dicarbonates with Carboxylic Acids Catalyzed by Weak Lewis Acids: General Method for the Synthesis of Anhydrides and Esters

Synthetic studies toward labionin, a new α,α‐disubstituted amino acid from type III lantibiotic labyrinthopeptin A2

Organocatalytic Nucleophilic Addition of Hydrazones to Imines: Synthesis of Enantioenriched Vicinal Diamines

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