Highly efficient Michael-type addition of acetaldehyde to β-nitrostyrenes by whole resting cells of Escherichia coli expressing 4-oxalocrotonate tautomerase

Comparisons of Halogenated β-Nitrostyrenes as Antimicrobial Agents

“…Significantly, this Michael addition reaction has been designed and performed in vivo in resting E. coli BL21 whole cells expressing 4-OT. This implies that the β-nitrostyrene used in the context as a reactant/substrate had no antibacterial effect on the host E. coli BL21 cells [21].…”

Synthesis of γ-nitroaldehydes containing quaternary carbon in the α-position using a 4-oxalocrotonate tautomerase whole-cell biocatalyst

“…30 During this study the scope of the biocatalytic reaction based on 4-OT was signicantly widened, so that biotransformations with both acyclic and cyclic branched aldehydes afforded good route to g-nitroaldehydes containing quaternary carbon in a-position but showed reduced enantiopurity. 30 During this study the scope of the biocatalytic reaction based on 4-OT was signicantly widened, so that biotransformations with both acyclic and cyclic branched aldehydes afforded good route to g-nitroaldehydes containing quaternary carbon in a-position but showed reduced enantiopurity.…”

“…Hence, the aromatic nature of the ring was concluded necessary for reaction to occur. This was surprising, as in the similar reaction using the same biocatalyst and acetaldehyde as donor, p-chloro-trans-b-nitrostyrene (2) was successfully transformed to 3-(4-chlorophenyl)-4-nitrobutanal with 38% isolated product yield, 30 suggesting the steric importance of the Michael donor in this reaction. Desired product yields, as estimated from the GC analysis were approximately 2-fold lower for 4a and 5a in comparison to 1a Table 1 Synthesis of 1a (2,2-dimethyl-4-nitro-3-phenylbutanal) through biotransformation of b-nitrostyrene (1) and isobutanal (a) by recombinant E. coli BL21 (4-OT) using 5 g CDW L À1 at 28 C, pH 7.2 in 60 mL volume with by-product of substrate reduction occurring at much higher percentage between 30-40% (results not shown).…”

“…30 Briey, this strain is recombinantly expressing 4-oxalocrotonate tautomerase (4-OT) from Pseudomonas putida mt-2 with inducible expression under control of T7 polymerase. 30 Briey, this strain is recombinantly expressing 4-oxalocrotonate tautomerase (4-OT) from Pseudomonas putida mt-2 with inducible expression under control of T7 polymerase.…”

“…30 Here we report on the extension of our biocatalytic strategy by showing that, 4-OT whole-cell biocatalyst also accepts variety of substituted aromatic and heterocyclic nitroalkenes as acceptors and branched aldehydes namely isobutanal, 2-ethylbutanal, cyclohexanecarbaldehyde and 2methylpentanal as donors for the Michael-type addition (Scheme 2; Fig. 30 Here we report on the extension of our biocatalytic strategy by showing that, 4-OT whole-cell biocatalyst also accepts variety of substituted aromatic and heterocyclic nitroalkenes as acceptors and branched aldehydes namely isobutanal, 2-ethylbutanal, cyclohexanecarbaldehyde and 2methylpentanal as donors for the Michael-type addition (Scheme 2; Fig.…”