New and efficient method for the preparation of medium-sized lactones from the corresponding ω-hydroxycarboxylic acids
Medium-sized lactones are prepared in good yields on treating monomeric cyclic silyl siloxycarboxylates, prepared in situ from ω-hydroxycarboxylic acids and 1,2-bisdimethylsilylbenzene using RhCl(PPh3)3 catalyst, with an active catalyst of dimethylsilylbis(trifluoromethanesulfonate).
A facile synthesis of lipid stabilized gold nanoparticles: A step towards biodegradable biosensors
A new class of polylactone was successfully synthesized and utilized for the encapsulation and stabilization of gold nanoparticles. Core/shell nanoparticle architecture, in which a layer of this polymer surrounds the nanoparticle core have been investigated both as a means to improve the stability and surface chemistry and as a way of accessing unique physical properties that are not possible from one nano-material alone. Given the fact that only few systems has so far been developed for the encapsulation of nanoparticles, our success in using a new biodegradable biopolymer with inbuilt functionality reveals the robustness of this work. The biodegradability of this polylactone was evaluated using scanning electron microscopy (SEM). The morphology and stability of these gold-polymer hybrids were evaluated by using the transmission electron microscopy (TEM) and UV-VIS spectroscopy.
Abraham, Sinoj,Narine, Suresh S.
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p. 7027 - 7032
(2012/05/20)
Scandium trifluoromethanesulfonate as an extremely active Lewis acid catalyst in acylation of alcohols with acid anhydrides and mixed anhydrides
Scandium trifluoromethanesulfonate (triflate), which is commercially available, is a practical and useful Lewis acid catalyst for acylation of alcohols with acid anhydrides or the esterification of alcohols by carboxylic acids in the presence of p-nitrobenzoic anhydrides. The remarkably high catalytic activity of scandium triflate can be used for assisting the acylation by acid anhydrides of not only primary alcohols but also sterically-hindered secondary or tertiary alcohols. The method presented is especially effective for selective macrolactonization of ω-hydroxy carboxylic acids.
A New Synthetic Method of Macrocyclic Lactones from ω-Iodoalkylacrylates
When the photostimulated cyclization reaction of ω-iodoalkylacrylates was performed in the presence of metal hydride complexes such as sodium cyanoborohydride (NaBH3CN), sodium borohydride (NaBH4) and potassium borohydride (KBH4), the corresponding macrocyclic lactones were produced.The use of NaBH3CN led to the highest yield of lactones.
Abe, Motoji,Hayashikoshi, Takaoki,Kurata, Takeo
p. 1789 - 1792
(2007/10/02)
Facile Synthesis of Lactones from Silyl ω-Siloxycarboxylates Using p-Trifluoromethylbenzoic Anhydride and a Catalytic Amount of Active Lewis Acid
The lactonization of silyl ω-siloxycarboxylates is successfully carried out under mild conditions in good to high yields by using p-trifluoromethylbenzoic anhydride and a catalytic amount of active acidic species generated in situ from TiCl4 and AgClO4.