447. The chemistry of fungi. Part XV. The degradation of methyl O-dimethylcitromycetin

Abstract

Methyl O-dimethylcitromycetin ( I ; R = Me), which is shown to have basic properties, is oxidised with lead tetra-acetate and chromic acid respectively to give methyl O-dimethylcitromycetinol (11) and methyl O-dimethylcitromycetinone (111). Unlike O-dimethylcitromycin, (I ; R = Me) is not oxidised to give (11) and ( 111) with ozone. The phenylpyrone (IV; R = H) is formed from (11) with alkali, whilst with warm dilute acid (111) gives (V) which on cyclisation regenerates the parent compound. With warm alkali (111) gives rise to (VI), (VIII), and probably (IX), along with acetone and acetic acid.Attempts to employ the ester (XIV; R = Me, R' = OH) as the starting material for the synthesis of (VI), (VIII), and (IX) were unsuccessful because (XIV; R = Me, R' = OH) could not be C-formylated or -acetylated. A new route to the synthesis of the acid (XIV; R = H, R' = OH) is described.

Identification of natural inhibitors of Entamoeba histolytica cysteine synthase from microbial secondary metabolites

“…Subsequently, about 2 mg of xanthofulvin ( Figure 3 ; Kumagai et al, 2003 ) was purified by preparative HPLC from 50 ml of the cultured broth. Two structurally related compounds, citromycetin ( Robertson et al, 1951 ; Capon et al, 2007 ) and terreinol ( Macedo et al, 2004 ) were also isolated from the 20% MeCN fraction and 40% MeCN fraction, respectively. The structures of the compounds were confirmed by 1D and 2D NMR spectra and MS spectra.…”

Citromycetins and Bilains A–C: New Aromatic Polyketides and Diketopiperazines from Australian Marine-Derived and Terrestrial Penicillium spp.

“…Structures for the known polyketides citromycetin ( 1 ) and citromycin ( 2 ) were determined by detailed spectroscopic analysis and comparison to literature data. Citromycetin ( 1 ) was first reported in 1931, and its structure solved 20 years later . Citromycin ( 2 ), on the other hand, has only been reported as an acid decomposition product of 1 .…”

“…Citromycetin (1) was first reported in 1931, 12 and its structure solved 20 years later. 13 Citromycin (2), on the other hand, has only been reported 12 as an acid decomposition product of 1. To assess whether our reisolation of 2 was a handling artifact, acidic (0.01% TFA) and basic (triethylamine to pH 8.5) 50% H 2 O/MeOH solutions of 1 were warmed to 40 °C and monitored by HPLC-DAD-ESI(()MS over several hours.…”

“…Repeated HPLC fractionation of the polar material yielded pure samples of the known polyketides citromycetin (1) 1 and citromycin (2), 2 together with two dihydro analogues, (-)-2,3-dihydrocitromycetin (3) and (-)-2, 3-dihydrocitromycin (4). This fractionation also yielded the known siderophore pistillarin (11) [3][4][5] and the known diketopiperazines cyclo-(L-Phe-L-Pro) (12), 6 cyclo-(L-Pro-L-Tyr) (13), 7 and cyclo-(L-Pro-L-Val) (14). 6 Repeated HPLC fractionation of the less polar material yielded the known diketopiperazine cis-bis(methylthio)silvatin (15) 8 along with three new diketopiperazines, bilains A-C (16)(17)(18).…”

“…An Australian terrestrial isolate of Penicillium striatisporum collected near Shalvey, New South Wales, also yielded citromycetin (1), citromycin (2), and the new dihydro analogue (-)-2,3-dihydrocitromycetin (3), together with fulvic acid (5), anhydrofulvic acid (6), and a selection of new methoxylated analogues, 12-methoxycitromycetin (7), 12-methoxycitromycin ( 8), (-)-12-methoxy-2,3-dihydrocitromycetin (9), and 12-methoxyanhydrofulvic acid (10). P. bilaii also yielded the rare siderophore pistillarin (11), the known diketopiperazines cyclo-(L-Phe-L-Pro) (12), cyclo-(L-Pro-L-Tyr) (13), cyclo-(L-Pro-L-Val) (14), and cisbis(methylthio)silvatin (15), and three new diketopiperazines, bilains A-C (16)(17)(18). The structures for the Penicillium metabolites 1-18 were assigned by a combination of detailed spectroscopic analysis, including correlation with relevant literature data, chemical derivatization, degradation, and biosynthetic considerations.…”