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The ring-opening of epoxidized methyl oleate by aqueous H 2 O 2 has been studied using tungsten and molybdenum catalysts to form the corresponding fatty β-hydroxy hydroperoxides. It was found that tungstic acid and phosphotungstic acid gave the highest selectivities (92-93 %) towards the formation of the desired products, thus limiting the formation of the corresponding fatty 1,2-diols. The optimized conditions were applied to a range of fatty epoxides to give the corresponding fatty β-hydroxy hydroperoxides with 30-80 % isolated yields (8 examples). These species were fully characterized by 1 H and 13 C NMR spectroscopy and HPLC-HRMS, and their stability was studied by differential scanning calorimetry. The thermal cleavage of the β-hydroxy hydroperoxide derived from methyl oleate was studied both in batch and flow conditions. It was found that the thermal cleavage in flow conditions gave the highest selectivity towards the formation of aldehydes with limited amounts of byproducts. The aldehydes were both formed with 68 % GC yield, and nonanal and methyl 9-oxononanoate were isolated with 57 and 55 % yield, respectively. Advantageously, the overall process does not require large excess of H 2 O 2 and only generates water as a byproduct., (© 2020 Wiley-VCH GmbH.)

The thiazolylidene-catalyzed cleavage of the α-hydroxy ketone derived from methyl oleate gave the corresponding aldehydes under nonoxidative conditions through a retro-benzoin process. The aldehydes produced are in equilibrium with their corresponding acyloins. To illustrate the synthetic utility of this protocol, the aldehydes were recovered by distillation., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The reaction of a chiral N-phenylnitrone derived from Garner's aldehyde with alkylarylketenes generates 3-alkyl-3-aryloxindoles directly in excellent yields and with good to excellent levels of enantioselectivity (up to 90% ee).

Substituted vinylene carbonates were directly prepared from aromatic aldehydes following a one‐pot Benzoin condensation/transcarbonation sequence under solvent‐free conditions. The combination of a N‐phenyl substituted triazolium salt NHC precursor and 4‐dimethylaminopyridine (DMAP) was found essential to reach high yield and selectivity. The reaction scope was investigated with a range of aromatic aldehydes and the corresponding vinylene carbonates were obtained with 32–86 % isolated yields (14 examples). [ABSTRACT FROM AUTHOR]

The peracetalization of a β-hydroxy hydroperoxide derived from methyl oleate was studied using benzaldehyde as a model substrate to give the corresponding fatty 1,2,4-trioxane. The desired product was obtained as a mixture of regioisomers but only one diastereoisomer of each was formed. The nature of the acid catalyst was studied and both p -toluene sulfonic acid (PTSA) and Amberlyst A35 (A35) were found to be efficient homogeneous and heterogeneous catalysts, respectively. The nature of the solvent was also investigated and ethereal solvents such as 2-methyltetrahydrofuran (2-MeTHF), methyl tert -butyl ether (MTBE) and cyclopentyl methyl ether (CPME) gave the best NMR yield (85%) for the preparation of the fatty trioxane. The optimized conditions were applied to a range of aromatic and aliphatic aldehydes, and the corresponding 1,2,4-trioxanes were isolated with 30–91% yields (21 examples). The antimalarial activity of three trioxanes was studied against Plasmodium falciparum, however, no significant activity was detected (IC50 >1600 nM). [ABSTRACT FROM AUTHOR]

Unsaturated vegetable oils and their corresponding fatty acid derivatives constitute interesting renewable platforms for the preparation of heterocycles, notably through the formation of oxygenated intermediates. In this work, fatty imidazoles were prepared from the corresponding 1,2‐diketones through Debus‐Radziszewski reaction. The reaction was optimized under microwave irradiation using a 1,2‐diketone derived from methyl oleate and ammonium acetate as a nitrogen source. Using benzaldehyde as a model substrate, the reaction occurs at 180 °C for 5 min and the desired imidazole was formed in 96 % GC yield. A range of aldehydes was tested under the optimized conditions and the corresponding imidazoles were obtained in 33–99 % isolated yields (20 examples). [ABSTRACT FROM AUTHOR]

The thermostable transketolase from Geobacillus stearothermophilus (TKgst) was successfully engineered for the synthesis of aliphatic acyloins with varying carbon backbone lengths (C5−C10) based on protein structure‐guided studies. Efficient TKgst variants were identified with enhanced activities for substrate combinations of aliphatic aldehydes as acceptors together with aliphatic pyruvate homologues as donors. The TKgst single variant L382F was able to catalyze efficiently the transfer of the ketol group from hydroxypyruvate on all targeted aliphatic aldehydes (C3−C8) to give the corresponding 1,3‐dihydroxy ketones with good yields and excellent enantioselectivity. The combination of the H102L/H474S mutation previously designed for the improved utilization of aliphatic pyruvate homologues together with a F435I exchange gave the new variant H102L/H474S/F435I, which is able to transfer the acyl goup of 2‐oxobutyrate and 2‐oxovalerate to aliphatic aldehydes, giving mono hydroxylated ketones. [ABSTRACT FROM AUTHOR]

The valorization of vegetable oil‐derived methyl azelaaldehydate (methyl 9‐oxo‐nonanoate) to monomers was studied through NHC‐catalysed Stetter reaction. Among the Michael acceptors tested, dimethyl fumarate gave the highest selectivity (97 %) for the corresponding Stetter adduct, thus limiting the competing benzoin condensation. Vegetable oil derived methyl azelaaldehydate (methyl 9‐oxo‐nonanoate) was converted to monomers through a NHC‐catalysed Stetter reaction, with limitation of the competing Benzoin condensation. [ABSTRACT FROM AUTHOR]

Abstract: A series of thiazolium salts was prepared and tested for the cleavage of the α‐hydroxyketone derived from methyl oleate. The robustness of these precatalysts was determined by dynamic thermogravimetric analyses (TGA). It has been shown that the stability of these species is mainly governed by the nature of the counter‐anion and some of them were found to be stable until 350–400 °C. The α‐hydroxyketone derived from methyl oleate was cleaved under reactive distillation conditions using optimized, thermally robust N‐butylthiazolium triflate to give the cleavage product, namely, nonanal and methyl azelaaldehydate, with 85 and 70 % yields. A range of α‐hydroxyketones derived from several fatty acids was cleaved to give the corresponding bio‐based aldehydes with up to 98 % isolated yields. Finally, this protocol was successfully applied to a high‐oleic sunflower oil derivative. [ABSTRACT FROM AUTHOR]

Amphiphilic sorbitan acetals have been prepared from sorbitan by acetalisation using linear aliphatic aldehydes or by transacetalisation starting from the corresponding aldehyde diethylacetals. A series of sorbitan acetals has been obtained with 29–81% isolated yields. It has been shown that these sorbitan acetals exist as a mixture of five-membered and six-membered regioisomers. Hydrogenolysis of the mixtures gave the corresponding sorbitan ethers as a mixture of 3 regioisomers with 55–85% isolated yields. A one-pot two-step procedure was also optimized from sorbitan giving similar results. The amphiphilic properties of sorbitan acetals and ethers were evaluated and both families exhibit interesting surfactant properties. [ABSTRACT FROM AUTHOR]

The effect of lithium halides on the enantioselectivity of the addition of methyllithium on o-tolualdehyde, in the presence of chiral lithium amides derived from chiral 3-aminopyrrolidines (3APLi), has been investigated. The enantiomeric excess of the resulting 1-o-tolylethanol was found to drop upon addition of significant amounts of LiCI, introduced before the aldehyde. The competitive affinity between the lithium amide, the methyllithium, and the lithium halides in THF was examined by multinuclear NMR spectroscopy and DFT calculations. The results showed that the original mixed aggregate of the chiral lithium amide and methyllithium is rapidly, totally, and irreversibly replaced by a similar 1:1 complex involving one lithium chloride or bromide and one lithium amide. While the MeLi/LiX substitution occurs with some degree of epimerization at the nitrogen for the endo-MeLi:3APLi complex, it is mostly stereospecific for the exo-type arrangements of the aggregate. The thermodynamic preference for mixed aggregates between 3APLi and LiX was confirmed by static DFT calculations: the data show that the LiCl and LiBr aggregates are more stable than their MeLi counterparts by more than 10 kcal·mol-1 provided THF is explicitly taken into account. These results suggest that a sequestration of the source of chirality by the lithium halides is at the origin of the detrimental effect of these additives on the ee of the model reaction. [ABSTRACT FROM AUTHOR]