Enantioselective Baeyer–Villiger Oxidation of Bicyclo[3.2.0]hept-2-en-6-One with Fungi: Optimization of Biotransformation and Use of TiO2 as Support of Cell Growth

Abstract

Fungi from Amazonian forest soil (Ecuador) and an Italian factory were screened for Baeyer-Villiger (BV) oxidation of bicyclo [3.2.0]hept-2-en-6-one to 2-oxabicyclo[3.3.0]oct-6-en-3-one (Corey's lactone). Isolates of Fusarium sp. and F. solani produced the (+)-(1R,5S)-lactone while isolates of Aspergillus terricola and A. amazonicus afforded the (-)-(1S,5R)-lactone. Highest conversions (85% yield and 70% enantiomeric excess) were obtained with A. amazonicus grown in presence of 2.7 mM titanium dioxide.

Prevalence and specificity of Baeyer–Villiger monooxygenases in fungi

“…Alphand et al (1998) showed that predominantly abnormal lactone was produced by Cunninghamella strains. Fantin et al (2006) also observed that Fusarium species mainly produced the (+)-normal lactone, while Aspergillus species afforded the (À)-normal lactone.…”

“…Although the first descriptions of microbial BV oxidation concerned fungal strains, and BV activities have been identified in various ascomycetes (Ouazzani-Chahdi et al, 1987;Carnell and Willetts, 1992;Königsberger et al, 1990;Goncalvez et al, 2004;Fantin et al, 2006), only seven enzymes out of the almost one hundred confirmed BVMOs are of eukaryotic origin: cyclohexanone monooxygenase (CHMO) from Exophiala jeanselmei (Hasegawa et al, 2000), cycloalkanone monooxygenase (CAMO) derived from Cylindrocarpon radicicola (Leipold et al, 2012), BVMO Af1 from Aspergillus fumigatus (Mascotti et al, 2013) and four BVMOs from Aspergillus flavus (Ferroni et al, 2014). Screening of 345 eukaryotic microorganisms (Carballeira et al, 2004) revealed only six BV activities, mostly from yeasts, pointing to a low prevalence of BVMOs in fungi.…”