Activated Zinc Dust

Smith, Craig R.

doi:10.1055/s-0029-1217181

Cited by 10 publications

(14 citation statements)

References 21 publications

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“…The next step was supposed to be the conversion of epoxyfarnesol to the corresponding triflate and a reduction of the epoxide by activated zinc powder and acetic acid [24]. Because the authors do not mention which of the multiple ways of zinc powder activation [34] they employed, we attempted the activation by TMSCl addition [35] or by stirring with diluted HCl to remove oxides from the surface [34]. The reaction of triflate with inactivated zinc powder led only to the isolation of epoxyfarnesol, and both experiments with activated zinc provided only the decomposed starting material.…”

Section: Enantiodivergent Synthesis Of (3r6e)-nerolidolmentioning

confidence: 99%

(3R,6E)-nerolidol, a fertility-related volatile secreted by the queens of higher termites (Termitidae: Syntermitinae)

Havlíčková

Dolejšová

Tichý

et al. 2019

Zeitschrift Für Naturforschung C

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The queens of advanced social insects maintain their reproductive monopoly by using exocrine chemicals. The chemistry of these “queen pheromones” in termites is poorly known. We show that primary queens of four higher termites from the subfamily Syntermitinae (Embiratermes neotenicus, Silvestritermes heyeri, Labiotermes labralis, and Cyrilliotermes angulariceps) emit significant amounts of the sesquiterpene alcohol (E)-nerolidol. It is the dominant analyte in queen body washes; it is present on the surface of eggs, but absent in kings, workers, and soldiers. In E. neotenicus, it is also produced by replacement neotenic queens, in quantities correlated with their fertility. Using newly synthesised (3R,6E)-nerolidol, we demonstrate that the queens of this species produce only the (R) enantiomer. It is distributed over the surface of their abdomen, in internal tissues, and in the haemolymph, as well as in the headspace of the queens. Both (R) and (S) enantiomers are perceived by the antennae of E. neotenicus workers. The naturally occurring (R) enantiomer elicited a significantly larger antennal response, but it did not show any behavioural effect. In spite of technical difficulties encountered in long-term experiments with the studied species, (3R,6E)-nerolidol remains among eventual candidates for the role in queen fertility signalling.

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Section: Enantiodivergent Synthesis Of (3r6e)-nerolidolmentioning

confidence: 99%

(3R,6E)-nerolidol, a fertility-related volatile secreted by the queens of higher termites (Termitidae: Syntermitinae)

Havlíčková

Dolejšová

Tichý

et al. 2019

Zeitschrift Für Naturforschung C

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“…Thus, methanolic solution of the amine N ‐oxides was admixed with anhydrous ammonium formate, silica gel (1 g), and freshly prepared Zn dust at room temperature. Work up after 10–20 min involving filtration over celite, evaporation of MeOH, extraction with CHCl 3 , and evaporation of the solvents afforded nearly pure amines in good yields (80–98%) without column chromatography.…”

Section: Resultsmentioning

confidence: 99%

An Improved Rapid and Mild Deoxygenation of Amine N‐oxides

Rajesh

2017

Journal of Heterocyclic Chem

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An improved mild and selective method for the deoxygenation of a variety of amine N‐oxides has been carried out in the presence of silica gel under mild conditions at room temperature to afford corresponding amines in relatively good yields without purification. The reaction is tolerant of a variety of functional groups such as hydroxyl, ester, acid, carbonyl, and cyano groups, as well as halogens. This method would be of great utility to synthesize various pyridines and amines easily.

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“…To a solution of nitrone 21 in THF (≈ 2.5 mL per 1 mmol) activated zinc powder (5 equiv.) was added, followed by addition of saturated aqueous NH 4 Cl solution (1:1 solvent ratio).…”

Section: Methodsmentioning

confidence: 99%

Total Synthesis of the Natural Herbicide MBH‐001 and Analogues

et al. 2020

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The first total synthesis of the natural herbicide MBH-001 (1) is reported. Structurally it is a 2-methyloxazol-5(2H)-one with a (1-hydroxyethyl) substituent at the 2-position. By relying on cyclic nitrones, a flexible route to MBH-001 and relevant analogues was developed. Key steps include the reaction of a 2-hydroxyimino ester with an aldehyde to form a 5-oxo-2,5dihydrooxazole 3-oxide. In an aldol-type reaction, the anion of these cyclic nitrones reacted with an aldehyde at the 2-position.[a] Scheme 1. Retrosynthetic considerations for MBH-001 (1) and the issue of regioselectivity in reactions of oxazolones with electrophiles. Results and DiscussionInitial studies were performed on oxazolone 4b, obtained by the Steglich method from acylated amino acid [6] 10 using water soluble carbodiimide [7] 11 (Scheme 2). Reaction of aromatic aldehydes 12a-c with oxazolone 4b (isomer of 4a) in the presence of triethylamine or diisopropylethylamine (Hünig′s base) provided the desired addition products with the carbinol connected to C2 (Scheme 2). However, preliminary tests showed that these aryl analogues 13a-13c of MBH-001 have no significant herbicidal activity.Unfortunately, the reaction of oxazolone 4b with acetaldehyde under identical conditions took a different course (Scheme 3). Thus, it seems hydroxyalkylation takes places at C4 to form intermediate A. This intermediate could not be isolated since it reacted with another acetaldehyde molecule to intermediate B followed by opening of the oxazolone ring and formation of 1,3-dioxanone 14, whose structure was confirmed by a single-crystal X-ray diffraction. We cannot rule out that other stereoisomers are formed in this transformation. The aldol-like reaction between 4b and acetaldehyde might be diastereo-Eur.

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Activated Zinc Dust

Cited by 10 publications

References 21 publications

(3R,6E)-nerolidol, a fertility-related volatile secreted by the queens of higher termites (Termitidae: Syntermitinae)

(3R,6E)-nerolidol, a fertility-related volatile secreted by the queens of higher termites (Termitidae: Syntermitinae)

An Improved Rapid and Mild Deoxygenation of Amine N‐oxides

Total Synthesis of the Natural Herbicide MBH‐001 and Analogues

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