244008-54-6Relevant articles and documents
Syntheses of new phosphorus-containing azabicycloalkanes and their microbial hydroxylation using Beauveria bassiana
Hemenway, Michael S.,Olivo, Horacio F.
, p. 6312 - 6318 (2007/10/03)
Representative novel phosphorus-containing azabicyclic substrates have been synthesized and subsequently microbially hydroxylated in fair to good yields using the microorganism Beauveria bassiana. (7-Azabicyclo[2.2.1]hept- 7-yl)phosphonic acid diethyl ester was hydroxylated at the unactivated methylene carbon to give (2-endo-hydroxy-7-azabicyclo[2.2.1]hept-7- yl)phosphonic acid diethyl ester in 43% yield and 64% ee, while N- (diphenylphosphinoyl)-7-azabicyclo[2.2.1]heptane was similarly hydroxylated to give 2-endo-hydroxy-7-(diphenylphosphinoyl)-7-azabicyclo[2.2.1]heptane in 35% yield and 20% ee. (7-Azabicyclo[2.2.1]hept-7-yl)phosphonic acid diphenyl ester yielded two distinct hydroxylated products: monohydroxylated (2-endo- hydroxy-7-azabicyclo[2.2.1]hept-7-yl)phosphonic acid diphenyl ester in 7% yield and 7% ee and dihydroxylated (2-endo-hydroxy-7-azabicyclo[2.2.1]hept-7- yl)phosphonic acid phenyl, p-hydroxyphenyl ester in 37% yield and 77% ee. HPLC studies indicated that the monohydroxylated metabolite is formed first during fermentation, and becomes a substrate for a second enzymatic hydroxylation at one of the aromatic rings with induced enantioselection, to give the dihydroxylated metabolite. All microbially hydroxylated metabolites were easily N-deprotected using TFA-CH2Cl2 (1:1). Thus, N-phosphinyl groups are good facilitators of hydroxylation reactions with B. bassiana and offer a new choice for an N-substituent when substrates are hydroxylated with this microorganism. By offering a new N-substituent, this work extends the general utility of B. bassiana as a preparatively useful unactivated methylene hydroxylator.
