23577-78-8Relevant academic research and scientific papers
Biocatalysis: Fungi mediated novel and selective 12β- or 17β-hydroxylation on the basic limonoid skeleton
Haldar, Saikat,Kolet, Swati P.,Thulasiram, Hirekodathakallu V.
, p. 1311 - 1317 (2013)
Basic limonoids carrying a 4,4,8-trimethyl-17-furanylsteroid skeleton are a class of triterpenoids and well-known for their insecticidal as well as a vast array of pharmacological activities. Rare and synthetically challenging 12β- and 17β-hydroxylation was achieved on the basic limonoid skeleton to produce a novel series of hydroxylated limonoids using fungi-mediated biocatalysis. The fungal system belonging to the genera of Mucor efficiently converted azadiradione, epoxyazadiradione, gedunin and their derivatives into corresponding 12β- and/or 17β-hydroxy derivatives. The position and stereochemistry of hydroxylation was determined by rigorous spectroscopic and crystallographic studies. This fungi-mediated stereo- and regio-selective hydroxylation process was highly efficient and mild enough to sustain chemically sensitive functional groups around the basic limonoid skeleton. Modifications of specific functional groups and variation in biocatalyst were shown to bring selectivity among 12β- or 17β-hydroxylation.
The Synthesis of a 1α,2α,3α-Triacetoxy Limonoid
Kehrli, Anne R. H.,Taylor, David A. H.,Niven, Margaret
, p. 2057 - 2065 (2007/10/02)
The report that Meerwein-Ponndorf reduction of gedunin (1a) gives 3α-hydroxy-3-deoxogedunin (2a) is wrong; the product is the 3β-epimer (2b). 3α-Acetoxy-7-deacetoxy-3-deoxo-7-oxgedunin (3c) was prepared by a stereospecific synthesis from cedrolide (1b), 7-deacetoxy-7-oxogedunin; osmium tetroxide oxidation then gave the 1,2α-glycol, isolated as the acetate (4a).Similarly, oxidation of the 3β-alcohol (3b) also gave the α-oriented glycol, as anticipated from the steric hindrance of the β-face of the molecule.Oxidation of the allylic alcohols (2b) or (3b), or of the allylic acetate (2d) with perbenzoic acid also takes place from the α-face of the molecule, giving the corresponding α-oxides (5a-c).The oxidation is pH sensitive; with a benzoate buffer the 7-oxo group in alcohol (3b) undergoes Baeyer-Villiger oxidation, giving the ε-lactone isolated as the acetate (6a).Opening of the oxide ring in the 3β,7α-diacetoxy oxide (5c) is complex.Identification of the products shows that the reaction involves participation by both the acetate groups.In contrast the 3β-acetoxy-7-oxo compound (5d) and the ε-lactone (6a) give the products of ring opening with assistance from the neighbouring acetate group, while the 3β-hydroxy compound (5b) gives the simple bromohydrin.
A New Limonoid Glycoside from the Stem Bark of Melia azedarach Linn.
Saxena, Meera,Srivastava, Santosh K.
, p. 1087 - 1088 (2007/10/02)
Chemical and spectral evidences are presented for characterizing a new limonoid glycoside as 7α-acetoxy-14β,15β-epoxy-gedunan-1-ene-3-O-β-D-glucopyranoside (I) isolated from the stem bark of Melia azedarach Linn.
