Chemistry of L-Ascorbic Acid: Regioselective and Stereocontrolled 2-C- and 3-C-Allylation via Thermal Claisen Rearrangement
作者:Kandatege Wimalasena、Mathew P. D. Mahindaratne
DOI:10.1021/jo00091a036
日期:1994.6
We report the convenient preparation of 3-O- and 2-O-allylated derivatives of 5,6-O-isopropylidene-L-ascorbic acid (1) with various allyl substituents in high yield and their quantitative thermal Claisen rearrangement to the corresponding 2-C- and 3-C-allylated derivatives with high regio- and stereoselectivity under relatively mild conditions. This reaction will now allow the synthesis of heretofore unknown 3-C-allylated derivatives of L-ascorbic acid in high yield. The high chiral induction at the substituents of the allylic carbon, especially in the case of the 3-O-methyl-2-O-crotyl derivative, is intriguing. This general method of preparation of 2-C- and 3-C-allylated derivatives of ascorbic acid may have important applications in synthetic organic and pharmaceutical chemistry.
Rational Approach to Selective and Direct 2-<i>O</i>-Alkylation of 5,6-<i>O</i>-Isopropylidine-<scp>l</scp>-ascorbic Acid
作者:Ayodele O. Olabisi、Kandatege Wimalasena
DOI:10.1021/jo049319i
日期:2004.10.1
derivatives of l-ascorbicacid have been shown to possess antioxidant, antitumor, and immunostimulant activities. The antioxidant and redox properties of l-ascorbicacid are closely associated with the electron-rich 2,3-enediol moiety of the molecule, and therefore, selective functionalization of the 2- and 3-OH groups is essential for the detailed structure−activity studies. Reactions of 5- and 6-OH-protected
A Convenient Entry to C2- and C3-Substituted Gulono-γ-lactone Derivatives from <scp>l</scp>-Ascorbic Acid
作者:Ayodele O. Olabisi、Mathew P. D. Mahindaratne、Kandatege Wimalasena
DOI:10.1021/jo0508550
日期:2005.8.1
method to obtain unknown chiral C2- and C3-functionalized aldono-1,4-lactone derivatives starting from l-ascorbic acid, which would be valuable in the synthesis of derivatives of various pharmacologically active agents for structure−activity studies, is described. The practicality of this approach is demonstrated by the synthesis of a series of 5,6-O-isopropylidene-2-allyl-3-keto-l-galactono-γ-lactone