42772-82-7Relevant articles and documents
Rhodium-phosphoramidite catalyzed alkene hydroacylation: Mechanism and octaketide natural product synthesis
Von Delius, Max,Le, Christine M.,Dong, Vy M.
supporting information, p. 15022 - 15032 (2012/11/06)
We describe a method that allows salicylaldehyde derivatives to be coupled with a wide range of unactivated alkenes at catalyst loadings as low as 2 mol %. A chiral phosphoramidite ligand and the precise stoichiometry of heterogeneous base are key for high catalytic activity and linear regioselectivity. This protocol was applied in the atom- and step-economical synthesis of eight biologically active octaketide natural products, including anticancer drug candidate cytosporone B. Mechanistic studies provide insight on parameters affecting decarbonylation, a side reaction that limits the turnover number for catalytic hydroacylation. Deuterium labeling studies show that branched hydride insertion is fully reversible, whereas linear hydride insertion is largely irreversible and turnover-limiting. We propose that ligand (R a,R,R)-SIPHOS-PE effectively suppresses decarbonylation, and helps favor a turnover-limiting insertion, by lowering the barrier for reductive elimination in the linear-selective pathway. Together, these factors enable high reactivity and regioselectivity.
Photo-fries rearrangements of phenyl phenylacylates in polyethylene films. Comparison of reactivity and selectivity with 1-naphthyl phenylacylates
Gu,Weiss
, p. 1775 - 1780 (2007/10/03)
The fates and kinetics of recombination of singlet radical pairs generated by photolyses of three phenyl phenylacylates have been examined in unstretched and stretched polyethylene films. Comparisons with results from photolyses of analogous 1-naphthyl phenylacylates in the same media lead to the conclusions that (1) phenoxy is less reactive overall than 1-naphthoxy toward a common phenylacyl radical but (2) the constrained cages in which the radical pairs reside exert greater control over the movements of the 1-naphthoxy/phenylacyl pairs. The reasons for these observations are discussed in the context of the shapes and van der Waals volumes of the radical pairs, the void volumes of sites in native polyethylene films, and the electronic properties of the aryloxy radicals. The fates and kinetics of recombination of singlet radical pairs generated by photolyses of three phenyl phenylacylates have been examined in unstretched and stretched polyethylene films. Comparisons with results from photolyses of analogous 1-naphthyl phenylacylates in the same media lead to the conclusions that (1) phenoxy is less reactive overall than 1-naphthoxy toward a common phenylacyl radical but (2) the constrained cages in which the radical pairs reside exert greater control over the movements of the 1-naphthoxy/phenylacyl pairs. The reasons for these observations are discussed in the context of the shapes and van der Waals volumes of the radical pairs, the void volumes of sites in native polyethylene films, and the electronic properties of the aryloxy radicals.
Synthesis of α-methyldeoxybenzoins
Salakka,Waehaelae
, p. 2601 - 2604 (2007/10/03)
Reduction of hydroxy and/or methoxy-substituted isoflavones using LiAlH4 in refluxing THF provides an easy access to a number of α-methyldeoxybenzoins, possible metabolites of phytoestrogens in man. The synthesis of O-demethylangolensin 2b, 6′-hydroxyangolensin 2c, angolensin 2d, 1-(2,4-dihydroxyphenyl)-2-phenylpropan-1-one 2e, 1-(2-hydroxy-4-methoxyphenyl)-2-(4-hydroxyphenyl)propan-1-one2f, 4′-O-methylangolensin 2g, 1-(2-hydroxy-4-methoxyphenyl)-2-phenylpropan-1-one 2h, and 1-(2-hydroxyphenyl)-2-phenylpropan-1-one 2i is described. The Royal Society of Chemistry 1999.
