Biodegradable micelles from a hyaluronan-poly(ε-caprolactone) graft copolymer as nanocarriers for fibroblast growth factor 1.

A novel copolymer (HA-g-PCL) was prepared by grafting hydrophobic poly(ε-caprolactone) (PCL) chains onto the backbone of hydrophilic hyaluronic acid (HA) with a grafting ratio of ∼7%. The copolymer formed micelles with a size of ∼60 nm in aqueous solution over a critical concentration of ∼4 μg mL. Each micelle consisted of about four copolymer chains.

Gold-catalyzed stereoselective synthesis of 9-oxabicyclo[3.3.1]nona-4,7-dienes from diverse 1-oxo-4-oxy-5-ynes: a viable formal [4 + 2] cycloaddition on an s-trans-heterodiene framework.

We report a highly stereoselective Au-catalyzed synthesis of 9-oxabicyclo[3.3.1]nona-4,7-dienes from diverse 1-oxo-4-oxy-5-ynes.

Gold-catalyzed stereocontrolled oxacyclization/[4+2]-cycloaddition cascade of ketone-allene substrates.

We report the first success on the Au-catalyzed tandem oxacyclization/[4+2]-cycloaddition cascade using ketone-allene substrates to give highly substituted oxacyclics with excellent stereocontrol. In contrast to oxo-alkyne substrates, the resulting cycloadducts are isolable and efficiently produced from a reasonable scope of enol ethers.

Gold-catalyzed deoxygenative nazarov cyclization of 2,4-dien-1-als for stereoselective synthesis of highly substituted cyclopentenes.

Treatment of 2,4-dien-1-als with allylsilanes and PPh(3)AuSbF(6) (3 mol %) led to formation of 1,4-bis(allyl)cyclopentenyl products; this gold catalyst is superior to commonly used Lewis acids according to catalyst screening. Such gold-catalyzed deoxygenative cyclizations are compatible with various oxygen-, amine-, sulfur-, hydrogen-, and carbon-based nucleophiles. The value of this new catalysis is demonstrated by the diverse annulations of 2,4-dien-1-als with electron-rich alkenes and arenes, providing an easy access to complicated cyclopentenyl frameworks.