نتایج جستجو برای: unsaturated compounds
تعداد نتایج: 241045 فیلتر نتایج به سال:
Oxidative stress has become an important subject for terrestrial and aquatic toxicology. The trace element selenium has been demonstrated in chemo-prevention and drug-resistance through reduction of oxidative stress. Selenium compounds could prevent damage to the unsaturated fatty acid of subcellular membranes by lipid peroxidation induced by free radicals in fish.
Irradiation of &methyl spiro [2.5] oct-7-en-4-one through its singlet excited state resulted in the formation of 4-methyl spirO [2.5] oct-4-en -6-one. We have used the cyclopropyl moiety in the molecule as a probe to study the operating mechanism in the photochemistry of ?, ?-unsaturated compounds. The results showed that this photoisomerization probably occurs through a concerted process.
The 5-endo-trig-type cyclization has been performed using a Pd-bis(isoxazoline) catalyst. The present cyclization of β,γ-unsaturated carbonyl compounds gave γ-butenolides and 3-pyrrolin-2-ones in good to excellent yields.
A rhodium-catalyzed [2 + 2 + 2] cycloaddition of cyano-yne-allene scaffolds followed by a dehydrogenative process enabling the direct synthesis of unsaturated pyridine-containing compounds that can be conveniently converted to 2,6-naphthyridine derivatives is reported.
The catalytic asymmetric phospha-Michael reaction of dialkyl phosphine oxides with β,β-disubstituted α,β-unsaturated carbonyl compounds was achieved. The products bearing tetrasubstituted carbon stereocenters were obtained in high yields with excellent enantioselectivities (up to >99% ee).
A new highly catalytic enantioselective Michael addition of fluorobis(phenylsulfonyl)methane to alpha,beta-unsaturated aldehydes has been developed for the preparation of chiral monofluoromethyl compounds under mild reaction conditions.
[Pd(NHC)(PR(3))] complexes were shown to be active catalysts in the dehydrogenation of ammonia borane and the subsequent hydrogenation of unsaturated compounds at very low catalyst loadings (0.05 mol% for some substrates).
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