نتایج جستجو برای: formation of aldehyde
تعداد نتایج: 21205259 فیلتر نتایج به سال:
Enantioselective total synthesis of (-)-pironetin: iterative aldol reactions of thiazolidinethiones.
The enantioselective total synthesis of pironetin has been achieved in 11 steps from known aldehyde 2. The synthesis relies on the formation of 5 out of 6 stereocenters through titanium mediated iterative aldol reactions. Key steps in this synthesis include an acetal aldol reaction to establish the stereochemistry at C8 and C9, an acetate aldol reaction, and "Evans" syn aldol reaction.
The development of one-pot imine formation and asymmetric Pictet-Spengler reactions cocatalyzed by a chiral thiourea and benzoic acid is described. Optically active tetrahydro-beta-carbolines, ubiquitous structural motifs in biologically active natural products, are obtained in high ee directly from tryptamine and aldehyde precursors.
Incubation of sheep liver cytoplasmic aldehyde dehydrogenase with the substrate 4-nitrophenyl [14C]acetate in the presence of NADH leads to the formation of 14C-labelled acetaldehyde. This observation strongly supports the idea that the esterase and dehydrogenase activities of the enzyme occur at the same site and involve the intermediacy of a common acyl-enzyme.
Lysyl hydroxylase 2 (LH2) catalyzes the hydroxylation of lysine residues in the telopeptides of fibrillar collagens, which leads to the formation of stable collagen cross-links. Recently we reported that LH2 enhances the metastatic propensity of lung cancer by increasing the amount of stable hydroxylysine aldehyde-derived collagen cross-links (HLCCs), which generate a stiffer tumor stroma (Chen...
[reaction: see text]. Facial selectivity in the addition of boron enolates of alpha-oxygenated ketones to anti-disposed alpha,beta-bisalkoxy aldehydes is controlled by the aldehyde vicinal diol protecting group. Protection of the diol as an acetonide results in the exclusive formation of the anti-syn-anti stereoarray found in the C(33)-C(36) region of aflastatin A.
The formation of a nickeladihydrofuran by oxidative cyclization of an alkyne and an aldehyde with nickel(0) has been demonstrated; the transformation of the nickeladihydrofuran into an enone by decomposition, a lactone by carbonylation and an allylic alcohol by treatment with ZnMe(2) suggests that nickeladihydrofuran is an important key intermediate in a variety of catalytic reactions.
A morphological transformation from hybrid micelles to giant vesicles was observed in aqueous dispersion associated with formation of a double-chained amphiphile as a result of the migration of dodecylamine from the amphiphilic imine to the amphiphilic aldehyde within the hydrophobic environment of amphiphilic aggregates.
Isoxazoline analogues of artemisinin were obtained in low yield and low diastereoselectivity from the 1,3-dipolar cycloaddition of nitrile oxides. Alternatively, starting from the aldehyde 7, a number of transformations--Wittig reaction and reduction, Henry reaction and cyanohydrin formation--were achieved in significantly higher yields. In the cases where a new stereocenter was introduced this...
We report a flexible de novo synthesis of phenolic dihydroxanthene fluorophores. The synthesis relies on a one-pot formation of an aldehyde intermediate which can be diversified in 60-70% overall yield, providing an efficient access to this family of near-infrared emitting fluorophores.
In higher plants, C6 and C9 aldehydes are formed from C18 fatty acids, such as linoleic or linolenic acid, through formation of 13- and 9-hydroperoxides, followed by their stereospecific cleavage by fatty acid hydroperoxide lyases (HPL). Some marine algae can also form C6 and C9 aldehydes, but their precise biosynthetic pathway has not been elucidated fully. In this study, we show that Laminari...
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