Stereoselective E/Z photoisomerization of oxazolidinone functionalized enecarbamates: direct and triplet sensitized irradiation.
نویسندگان
چکیده
Oxazolidinone-functionalized enecarbamates undergo diastereoselective E/Z photoisomerization upon direct and triplet sensitized irradiations with chiral/achiral sensitizers, showing that the enhanced product diastereoselectivity depends on the solvent and temperature.
منابع مشابه
Controlled diastereoselectivity at the alkene-geometry through selective encapsulation: E-Z photoisomerization of oxazolidinone-functionalized enecarbamates within hydrophobic nano-cavities.
Photoisomerization of encapsulated Z-enecarbamates within the hydrophobic chiral cavities of gamma-CD showed higher diastereoselectivities in the photoproducts than those obtained in solution. The selective encapsulation of the enecarbamates and the following isomerization process are both diastereoselectively controlled by gamma-CD.
متن کاملPhysical and chemical quenching rates and their influence on stereoselective photooxygenation of oxazolidinone-functionalized enecarbamates.
Physical and chemical quenching rate constants were measured for the reaction of singlet oxygen with oxazolidinone-functionalized enecarbamates to investigate the role of vibrational deactivation in product stereoselectivity.
متن کاملStereoselective photooxidation of enecarbamates: reactivity of ozone vs singlet oxygen.
[reaction: see text]. Oxazolidinone-functionalized enecarbamates show contrasting behavior upon oxidation by singlet oxygen and by ozone. The observed stereoselectivity difference indicates that the oxidation with ozone is subject to classic steric effects, whereas the very high selectivity in the photooxidation with singlet oxygen is derived from vibrational deactivation.
متن کاملThe reaction of singlet oxygen with enecarbamates: a mechanistic playground for investigating chemoselectivity, stereoselectivity, and vibratioselectivity of photooxidations.
Photochirogenesis, the control of chirality in photoreactions, is one of the most challenging problems in stereocontrolled photochemistry, in which the stereodifferentiation has to be imprinted within the short lifetime of the electronically excited state. Singlet oxygen (1O2), an electronically excited molecule that is known to be sensitive to vibrational deactivation, has been selected as a m...
متن کاملTemperature and solvent control of the stereoselectivity in the reactions of singlet oxygen with oxazolidinone-substituted enecarbamates.
Oxazolidinone-functionalized enecarbamates react stereoselectively with singlet oxygen to give methyldesoxybenzoin (MDB) in moderate to high enantiomeric excess. The stereochemical outcome depends on the E/Z substrate geometry, temperature, and solvent variables. The analysis of the differential activation parameters suggests a large contribution from the entropy term in determining the enantio...
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ورودعنوان ژورنال:
- Chemical communications
دوره 27 شماره
صفحات -
تاریخ انتشار 2005