Structure and absolute configuration of pyrophen, a novel pryrone derivative of L-phenylalanine from Aspergillus niger.

Pyrophen, a novel 4-methoxy-2-pyrone derivative of L-phenylalanine isolated from cultures of Aspergillus niger, crystallizes in the orthorhombic space group P2(1)2(1)2(1), with a = 8.918(1), b = 9.199(3), and c = 18.092(4) A. The structure was solved by direct methods and the absolute configuration assigned by the Bijvoet method. Refinement gave R = 0.045 and S = 1.78 for 1677 reflections with I greater than 3 sigma (I). Though numerous other pyrone natural products are known, including other products of A. niger, this is the first report of an amino acid-pyrone derivative.