- Synthetic studies toward the total synthesis of tautomycetin
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The studies culminating in the synthesis of two large subunits of tautomycetin are described. The first one, fragment C1-C12 that has an anti-1,3-dimethyl system and a terminal diene unit, was accomplished in 10 linear steps in 7.4% overall yield. The second one, fragment C13-C25 which bears the sensitive anhydride framework and the majority of the stereogenic centers, was prepared in 13 linear steps (longest sequence) in 8% overall yield. Among the key transformations used, a regioselective epoxide opening, a Pd-catalyzed addition of terminal alkyne to acceptor alkyne, a Mukaiyama aldol reaction, a Yamaguchi esterification, and a homemade mild di-esterification can be cited. The chosen strategies allowed good yields, stereoselectivity, reproducibility, and scalability for several important intermediates.
- Pereira De Sant'Ana, Danilo,De Oliveira Rezende Júnior, Celso,Campagne, Jean-Marc,Dias, Luiz Carlos,Marcia De Figueiredo, Renata
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p. 12344 - 12357
(2019/10/10)
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- Dirhodium(II)-Mediated Alkene Epoxidation with Iodine(III) Oxidants
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Dirhodium(II) complexes and iodine(III) oxidants have found useful applications in synthetic nitrene chemistry. In this study, the combination of the dirhodium(II) complex Rh2(tpa)4 (tpa = triphenylacetate) with the iodine(III) oxidant PhI(OPiv)2 is shown to promote the epoxidation of alkenes in the presence of 2 equivalents of water. The reaction can be applied to diversely substituted alkenes and the corresponding epoxides are isolated with yields of up to 90 %. A possible mechanism involves the dirhodium(II) complex as a Lewis acid species that would tune the oxidizing character of the iodine(III) reagent.
- Nasrallah, Ali,Grelier, Gwendal,Lapuh, Maria Ivana,Duran, Fernando J.,Darses, Benjamin,Dauban, Philippe
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supporting information
p. 5836 - 5842
(2018/11/24)
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- PROCESS TO PREPARE EPSILON-CAPROLACTAM
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The invention is directed to a process to prepare ε-caprolactam and/or unsaturated ε-caprolactam from a pentenamide by contacting the pentenamide with a mixture of hydrogen and carbon monoxide in the presence of a solvent and a catalyst system comprising of a Group 8-10 metal and a phosphorus-donor ligand. The ligand may be a xantphos-type ligand.
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Page/Page column 15
(2014/10/18)
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- Synthesis of γ-hydroxy α,β-unsaturated amides by base induced isomerization of epoxy amides
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Treatment of 3,4-epoxyamides with LDA affords γ-hydroxy-α,β- unsaturated amides, usually with high (E)-selectivity. The 3,4-epoxyamides were prepared by the epoxidation of β,γ-unsaturated amides with meta- chloroperbenzoic acid.
- Brooks, Peter B.,Marson, Charles M.
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p. 9613 - 9622
(2007/10/03)
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- Preparation of 3-pentenoic acid and a catalyst therefore
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Preparation of 3-pentenoic acid by the reaction of 3-pentenoylchloride, water and butadiene. 3-chloro-1-butene and 1-chloro-2-butene are also formed. Preferably the 3-pentenoylchloride is formed by the reaction of chlorobutene with carbon monoxide using a palladium catalyst.
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- INTRAMOLECULAR DIELS-ALDER CYCLOADDITIONS OF VINYLKETENIMINES. A CONVERGENT ROUTE TO CARBAZOLES AND PYRIDOCARBAZOLE ALKALOIDS
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The intramolecular Diels-Alder cycloaddition of acetylenic vinylketenimines is the key step of a highly convergent synthesis of carbazoles.A facile synthesis of N-methyl-tetrahydroellipticine has been completed in five isolated steps from N-methyl piperidone.
- Differding, Edmond,Ghosez, Leon
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p. 1647 - 1650
(2007/10/02)
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