نتایج جستجو برای: crossed aldol condensation
تعداد نتایج: 47212 فیلتر نتایج به سال:
Jet fuel range branched cycloalkanes with high density (0.82 g mL(-1)) and low freezing point (217-219 K) was first prepared by the solvent-free intramolecular aldol condensation of the trione from the hydrolysis of the alkylation product of mesityl oxide and 2-methylfuran (or the one-pot reaction of mesityl oxide, 2-methylfuran and water), followed by hydrodeoxygenation (HDO).
The title compound, C(17)H(15)ClO, was prepared from 3,4-dimethyl-benzaldehyde and 4-chloro-hypnone by Aldol condensation. The dihedral angle formed by the two benzene rings is 48.91 (8)°. Only van der Waals forces affect the packing.
[formula: see text] A novel pentacyclic polyhydroxylated sterol, xestobergsterol A (1a), has been synthesized in 24 steps and in good overall yield from stigmasterol 17. The key steps of the synthesis are the Breslow remote functionalization of the polyoxygenated steroid derived from 25 and the base-catalyzed epimerization-aldol condensation of the dione derived from 27.
Tetrahydroxanthenones, which can be easily prepared by a domino oxa-Michael aldol condensation, offer various possibilities for diastereoselective functionalization, giving access to the stereocontrolled synthesis of stereochemical triades or tetrades, which represent privileged structural motifs. In most cases, the relative stereochemistry was unequivocally established by crystal structure ana...
The title compound, C(15)H(17)FO, was prepared directly from the aldol condensation of cyclo-octa-none with 4-fluoro-benz-aldehyde, catalysed by Pd(Ni,Ce) in the presence of trimethyl-silyl chloride. The eight-membered ring adopts a boat-chair conformation.
Five new bulky moiety-modified analogues of the sandalwood odorant Polysantol have been synthesized by aldol condensation of appropriate aldehydes with butanone, deconjugative alpha-methylation of the resulting alpha,beta-unsaturated ketones, and reduction of the corresponding beta,gamma-unsaturated ketones. The final compounds were evaluated organoleptically and one of them seemed to be of spe...
The title compound, C(15)H(10)F(N)O(3), was prepared from 2-nitro-acetphenone and 4-fluoro-benzaldehyde by an Aldol condensation reaction. The dihedral angle formed by the two benzene rings is 67.37 (2)°. The crystal structure is stabilized by weak inter-molecular C-H⋯O and C-H⋯F hydrogen bonds.
The first enantiospecific synthesis of akaol A, a marine sesquiterpene quinol, has been achieved. Key steps of the synthetic sequence are the oxidative degradation of (-)-sclareol to a dinorlabdane ketoester, mediated by the ozone-lead(IV) acetate system, the diastereoselective α-methylation of a ketoaldehyde, followed by an intramolecular aldol condensation and the further Diels-Alder cycloadd...
A new heterogeneous catalyst, hydrophobic TiO4-deposited mesoporous silica, has been designed for the efficient Mukaiyama-aldol condensation, a water-participating Lewis acid-catalyzed reaction between a hydrophobic carbonyl compound and silyl enol ether. The prepared catalyst suspended in water exhibited high catalytic performance as a reusable catalyst for the reaction without a surfactant.
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