459174-25-5Relevant articles and documents
Enantio- And Diastereoselective Construction of Contiguous Tetrasubstituted Chiral Carbons in Organocatalytic Oxadecalin Synthesis
Wada, Yuuki,Murata, Ryuichi,Fujii, Yuki,Asano, Keisuke,Matsubara, Seijiro
supporting information, p. 4710 - 4715 (2020/07/06)
The organocatalytic enantio- and diastereoselective cycloetherification of 1,3-cyclohexanedione-bearing enones involving the in situ generation of chiral cyanohydrins was developed. This transformation offers the first catalytic asymmetric approach to oxa
The mechanism of 1,4 alkyl group migration in hypervalent halonium ylides: The stereochemical course
Moriarty, Robert M.,Tyagi, Sachin,Ivanov, Daniela,Constantinescu, Mircea
, p. 7564 - 7565 (2008/12/22)
Rhodium(II)-acetate-catalyzed decomposition of either 1,3-cyclohexanedione phenyliodonium ylide or 5,5-dimethyl-1,3-cyclohexanedione phenyliodonium ylide in the presence of alkyl halides yields the corresponding 3-alkoxy-2-halocyclohex-2-enones via a 1,4 alkyl group migration shown to be concerted and intramolecular. In the case of (S)-α-phenethyl chloride, the rearrangement proceeds with essentially 88.6% retention of configuration. Theoretical calculations at the B3LYP/6-31G level reveal an activation energy of 5.4 kcal/mol for the process. A Claisen-like rearrangement occurs in the case where allylic halides, such as dimethylallyl or methallyl chorides, are used. The mechanistic pathway proposed for these processes involves addition of the halogen atom of the alkyl or allyl halide to the rhodium carbenoid from the iodonium ylide to yield a halonium intermediate that undergoes halogen to oxygen group migration. Aryl halides, such as chloro-, bromo-, iodo-, and fluorobenzene, behave differently under the same reaction conditions, yielding the product of electrophilic aromatic substitution, namely, the 2-(4-halophenyl) 1,3-cyclohexanedione. Copyright
Reactions of a Cyclic Rhodium Carbenoid with Aromatic Compounds and Vinyl Ethers
Pirrung, Michael C.,Zhang, Jiancun,Lackey, Karen,Sternbach, Daniel D.,Brown, Frank
, p. 2112 - 2124 (2007/10/02)
Further investigation has been made of the reactions between the cyclic diazo compound 2-diazo-1,3-cyclohexanedione and aromatic heterocycles or vinyl ethers, catalyzed by rhodium carboxylates.The extraordinary reactivity of the carbenoid derived from this diazo compound is shown by its ready reaction with solvents such as dichloromethane, dichloroethane, and fluorobenzene.Detailed investigation of its reactions with furans have shown that steric interactions dominate, both in terms of regioselectivity with unsymmetrical substrates and yield.This reaction provides a useful entry to the furofuran ring system found in a number of naturally-occurring compounds and is formally a 1,3-dipolar cycloaddition.Products of net C-H insertion and with reverse regiochemistry (furofuran ring system) were also detected.With pyrroles and thiophenes, cycloadducts were seen in a few cases, but were generally the exception; C-H insertion products dominate these reactions.Vinyl ethers proved reliable reactants in providing dipolar cycloadducts.The results of this study have been interpreted in terms of four pathways: an initial cyclopropanation would produce a spirocyclic dicarbonyl system that on heterolytic cleavage of one of the two cyclopropane bonds would give a zwitterion.The partitioning of such a zwitterion between ring closure and proton transfer would define the ratio of C-H insertion and dipolar cycloaddition products.Both thermodynamic and stereoelectronic arguments have been advanced to explain the observations and were supported by calculations.
