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.
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.