cyclizations การใช้

• Polyphosphoric acids are used in organic synthesis for cyclizations and acylations.
• Silicon-directed Nazarov cyclizations can exhibit induced diastereoselectivity in this way.
• Similarly, ?-substitution directed inward restricts the s-trans conformation so severely that Interrupted cyclizations below)
• Curran is known for his pioneering work on organic radicals and radical cyclizations, especially directed towards organic synthesis.
• Similarly, electron-rich styrenes participate in intra-or intermolecular Diels Alder cyclizations via a radical cation mechanism.
• Another common problem associated with RCM is the risk of catalyst degradation due to the high dilution required for some cyclizations.
• Ru ( bipy ) 3 2 + was a competent catalyst for intermolecular, but not intramolecular, Diels Alder cyclizations.
• After this the olefin can isomerize to more thermodynamically stable positions, or can be activated for cyclizations, in order to produce the natural product.
• Other precursors to indole include formyltoluidine, 2-ethylaniline, and 2-( 2-nitrophenyl ) ethanol, all of which undergo cyclizations.
• Organotin compounds are also used extensively in radical chemistry ( e . g . radical cyclizations, Barton McCombie deoxygenation, Barton decarboxylation, etc . ).
• In addition, we hope that our explorations into a diverse set of epoxide opening cyclizations and cascades will shed further light on the fundamental feasibility of the Nakanishi s hypothesis.
• Since transannular strain is the largest source of strain in rings this size, the larger enthalpies of activation result in much slower cyclizations due to transannular interactions in the cyclic ethers.
• Once this napthoquinone has been made, a series of oxidations and cyclizations lead to two substrates that can undergo a [ 4 + 2 ] cycloaddition that leads to the product.
• Just as tin-mediated radical dehalogenation reactions can be used to initiate cascade cyclizations to rapidly generate molecular complexity, the photocatlytic reductive dehalogenation allows access to the same types of complex products.
• While Ru ( bipy ) 3 2 + proved to be a competent catalyst for intramolecular cyclizations using methyl viologen, it could not be used with molecular oxygen as an electron sink or for intermolecular cyclizations.
• While Ru ( bipy ) 3 2 + proved to be a competent catalyst for intramolecular cyclizations using methyl viologen, it could not be used with molecular oxygen as an electron sink or for intermolecular cyclizations.
• The cyclizations to form the tetramic acids 2, 4-pyrrolidinedione ring and the bicyclic ketal system, as well as the oxidative transformations in the bicyclic skeleton, were suggested but further experimental evidence was needed.
• Both the furanose and pyranose thiosugars can be prepared from the same thiyl radical precursor; 5-" exo " and 6-" endo " cyclizations of this precursor form the respective desired compound.
• Among the more common organic photochemical reactions there are the electrocyclic processes, the rearrangement of epoxyketones to beta-diketones, ring opening of cyclopropyl ketones, heterolysis of 3, 5-dimethoxylbenzylic derivatives, and photochemical cyclizations of dienes.
• For intermolecular cyclizations, Yoon et al . discovered that the more strongly oxidizing photocatalyst Ru ( bpm ) 3 2 + and molecular oxygen provided a catalytic system better suited to access the radical cation necessary for the cycloaddition to occur.