1 – Dynemicin A

: Dynemicin A 2-1 was first isolated in the mid-1980s from Micromonospora chersina, a soil microorganism collected in the state of Gujarat in India. From a 200 L culture broth, it was possible to obtain 5.7 mg of 2-1 as a violet amorphous solid after extraction and purification. The production of 2-1 was later improved by the addition of sodium iodide to the culture medium, which allowed isolation of up to 2 g of 2-1 from a 10 000 L fermentation broth. The presence of ionexchanging resins in the neutral culture medium also improved the efficiency. The spectroscopic characterization was facilitated by converting dynemicin A into the triacetate derivative 2-2, which is soluble in most organic solvents, and allowed unequivocal structural determination by single-crystal X-ray diffraction. Although the structure obtained by X-ray diffraction revealed the relative configurations of stereogenic centers, the absolute configuration of 2-1 was not firmly established until the first total asymmetric synthesis described by Myers in 1995 and 1997.