Crisamicin A, a new antibiotic from Micromonospora. I. Taxonomy of the producing strain, fermentation, isolation, physico-chemical characterization and antimicrobial properties.

First Synthesis of the Pyrano‐Naphthoquinone Lactone (–)‐Arizonin C1

“…The combined organic layers were washed with water (2 mL) and dried with Na 2 SO 4 . The solvent was removed under reduced pressure and the residue was purified by flash chromatography [34] [30 cm/1 cm, cyclohexane/AcOEt = 90:10 to 80:20 (v/v), fractions [8][9][10][11][12][13][14]. The title compound (51.1 mg, 85 %) was obtained as a yellow oil.…”

“…It extends from nanaomycin D [2] (1), kalafungin [3] (2a), the arizonins [4] (2b-d) and its simplified laboratory analogues [5] (6) to species like BE-54238B [6] (3), which is indolizidine-annulated, or medermycin/lactoquinomycin A [7][8][9][10] (4), which can be considered as a C-glycoside of kalafungin (2a) and a desoxyaminohexose. Crisamycin A [11] (5) appears to result from an oxidative homocoupling. There has been considerable recent interest both from biochemists and pharmacologists in the exploration and exploitation of pyrano-naphthoquinone lactones.…”

“…Arguably, the furthest-going synthetic effort to date [a] Institut für Organische Chemie and Biochemie, Universität Figure 1. Selected natural (1, [2] 2a, [3] 2b-d, [4] 3, [6] 4, [7][8][9][10] 5 [11] ) and unnatural (6 [5] ) pyrano-naphthoquinone-fused γ-lactones. [13] in this area has been the 19-step synthesis of a racemic mixture of two diastereomers of crisamycin A (5) by the group of Wang and Yang.…”

Isolation and structure determination of crisamicin A, a new antibiotic from Micromonospora purpureochromogenes subsp. halotolerans.

“…The powder was separated by HPLC as described above except for the solvent system (CHCl3, -CH3OH -H2O, 20: 70: 10; pH 2.5, adjusted with 1 N H2SO4), flow rate (2.5 ml/minute), and wavelength (432 nm). The HPLC trace showed two main fractions -3, with retention time 13 minutes and 20 seconds, and 4, with retention time 10 minutes and 48 seconds, which were collected, combined, and evaporated in vacuo, separately, to yield two methyl esters; compound 3 Methyl Ester 5 A solution of diazomethane was added to a solution of 2 (8.7 mg) in methanol (15 ml), dropwise with stirring in an ice bath, until the color changed. The mixture was evaporated in vacuo to dryness to give 11 mg of residue, which was chromatographed on a preparative plate as above using benzene -…”

Iodine‐Promoted Efficient Homocoupling of Arylboronic Acids in PEG‐400 under Aerobic Conditions

“…Crisamicin A, for example, which has been isolated from a mud sample in the Philippines, was found to be active primarily towards Gram-positive bacteria. [4] Biphenomycin B, which was previously isolated from culture filtrates of Streptomyces griseorubiginosus No. 43708, was found to be a highly potent antibiotic against Gram-negative, β-lactam-resistant bacteria.…”