Penicillium decumbens reduction

Much work has been published on the microbiological reduction of a,p-unsaturated ketones. Under anaerobic conditions the reduction of A -3-keto steroids by Clostridium paraputrificum led to the 3-keto 5p-derivatives (Scheme 69) Similar transformations were observed previously with Bacillus putrifi-cus, Penicillium decumbens Rhizopus nigricans or Aspergillus niger. In most cases further reduction led to the corresponding 3a-hydroxy 5P-derivatives. 

Sih (38) has described the reduction of E-l-iodo-l-octen-3-one with Penicillium decumbens to give the desired S-alcohol. Based on optical rotation, the e.e. was about 80%, An asymmetric chemical reduction of this same ketone, using lithium aluminum hydride that had been partially decomposed by one mole each of S-2,2 -dihydroxy-l,T-binaphthol and ethanol (42), gave the desired alcohol in 97% e.e. This reagent also reduced l-octyn-3-one in 84% e.e. to the corresponding alcohol (43). A 92% e.e. could be obtained with B-3-pinanyl-9-borabicyclo[3.3.1]nonane as the reducing agent (44). 

The stereogenic centre in the side-chain was formed by reduction of iodoenone (96) with Penicillium decumbens. The product (97)... 

---