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Homebrewing the 2-phenyl-nitroethanes
(Rated as: excellent)
Did you know that baker's yeast can bee used to reduce the double bond of the nitrostyrenes?
Then you still haven’t read Post 108516 (dormouse: "A new reducing agent for nitrostyrenes: bakers yeast! -Labrat", Novel Discourse).
Unfortunatelly that thread is closed so I’m uploading these papers in a new one. Maybe somebee can also upload some other pertaining papers cited in the old thread?
Asymmetric reduction of nitroalkenes with baker’s yeast.
Yasushi Kawai, Yoshikazu Inaba and Norihiro Tokitoh
Tetrahedron: Asymmetry 12 (2001) 309–318.
(the experimental was already posted by Post 352999 (foxy2: "Asymmetric reduction of nitroalkenes with baker's ...", Novel Discourse))
Abstract: Various alpha,beta-disubstituted and trisubstituted nitroalkenes were chemoselectively reduced with baker’s yeast to the corresponding nitroalkanes. Stereoselectivities of the reduction of a,b-disubstituted nitroalkenes were modest to low, and e.e.s up to 52% were obtained. Trisubstituted nitroalkenes could be reduced to the corresponding nitroalkanes with excellent enantioselectivities, moderate diastereoselectivities and in good yield.
More, but this time using the encime:
Asymmetric synthesis of a nitroalkane by the use of novel nitroalkene reductases from baker’s yeast.
Yasushi Kawai, Yoshikazu Inaba, Motoko Hayashi and Norihiro Tokitoh
Tetrahedron Letters 42 (2001) 3367–3368.
Abstract: Two kinds of novel nitroalkene reductases were isolated from baker’s yeast. Reduction of a trisubstituted nitroalkene by these reductases afforded the corresponding nitroalkane with excellent enantioselectivity, moderate diastereoselectivity, and in good yield.
The good old yellow encime – interesting kinetic studies:
Old Yellow Enzyme: Stepwise reduction of nitroolefins and catalysis of aci-nitro tautomerization.
Younus Meah and Vincent Massey
PNAS 97 (2000) 10733–10738.
Abstract: The Old Yellow Enzyme has been shown to catalyze efficiently the NADPH-linked reduction of nitro-olefins. The reduction of the nitro-olefin proceeds in a stepwise fashion, with formation of a nitronate intermediate that is freely dissociable from the enzyme. The first step involves hydride transfer from the enzyme-reduced flavin to carbon 2 of the nitro-olefin. The protonation of the nitronate at carbon 1 to form the final nitroalkane product also is catalyzed by the enzyme and involves Tyr-196 as an active site acidybase. This residue also is involved in aci-nitro tautomerization of nitroalkanes, the first example of a nonredox reaction catalyzed by the enzyme.
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