22451-50-9

Upstream product

• 18031-40-8 (S)-(-)-perillaldehyde 
• 5503-12-8 L-perillaldehyde 
• 2111-75-3 perillaldehyde 

Relevant academic research and scientific papers

Biocatalytic asymmetric alkene reduction: Crystal structure and characterization of a double bond reductase from Nicotiana tabacum

The application of biocatalysis for the asymmetric reduction of activated C=C is a powerful tool for the manufacture of high-value chemical commodities. The biocatalytic potential of "-ene" reductases from the Old Yellow Enzyme (OYE) family of oxidoreductases is well-known; however, the specificity of these enzymes toward mainly small molecule substrates has highlighted the need to discover "-ene" reductases from different enzymatic classes to broaden industrial applicability. Here, we describe the characterization of a flavin-free double bond reductase from Nicotiana tabacum (NtDBR), which belongs to the leukotriene B4 dehydrogenase (LTD) subfamily of the zinc-independent, medium chain dehydrogenase/reductase superfamily of enzymes. Using steady-state kinetics and biotransformation reactions, we have demonstrated the regio- and stereospecificity of NtDBR against a variety of α,β-unsaturated activated alkenes. In addition to catalyzing the reduction of typical LTD substrates and several classical OYE-like substrates, NtDBR also exhibited complementary activity by reducing non-OYE substrates (i.e., reducing the exocyclic C=C double bond of (R)-pulegone) and in some cases showing an opposite stereopreference in comparison with the OYE family member pentaerythritol tetranitrate (PETN) reductase. This serves to augment classical OYE "-ene" reductase activity and, coupled with its aerobic stability, emphasizes the potential industrial value of NtDBR. Furthermore, we also report the X-ray crystal structures of the holo-, binary NADP(H)-bound, and ternary [NADP+ and 4-hydroxy-3-methoxycinnamaldehyde (9a)-bound] NtDBR complexes. These will underpin structure-driven site-saturated mutagenesis studies aimed at enhancing the reactivity, stereochemistry, and specificity of this enzyme.

Nicotinamide-dependent Ene reductases as alternative biocatalysts for the reduction of activated alkenes

Four NAD(P)H-dependent non-flavin ene reductases have been investigated for their ability to reduce activated C=C bonds in an asymmetric fashion by using 20 structurally diverse substrates. In comparison with flavin-dependent Old Yellow Enzyme homologues, a higher degree of electronic activation was required, because the best activities were obtained with enals and nitroalkenes rather than enones and carboxylic esters. Although FaEO from Fragaria x ananassa (strawberry) and its homologue SlEO from Solanum lycopersicum (tomato) exhibited a narrow substrate spectrum, progesterone 5β-reductase (At5β-StR) from Arabidopsis thaliana (thale cress) and leukotriene B4 12-hydroxydehydrogenase (LTB4DH/PGR) from Rattus norvegicus (rat) appear to be promising candidates, in particular for the asymmetric bioreduction of open-chain enals, nitroalkenes and α,β-unsaturated γ-butyrolactones. Competing nitro reduction and non-enzymatic Weitz-Scheffer epoxidation were largely suppressed. Electronically activated alkenes have been stereoselectively reduced by using a single-enzyme-cofactor system employing nicotinamide-dependent non-flavin ene reductases. Copyright

Site-saturation mutagenesis of tryptophan 116 of saccharomyces pastorianus old yellow enzyme uncovers stereocomplementary variants

Site-saturation mutagenesis was used to generate all possible replacements for Trp 116 of Saccharomyces pastorianus (formerly Saccharomyces carlsbergensis) old yellow enzyme (OYE). Our original hypothesissthat smaller amino acids at position 116 would allow better acceptance of bulky 3-alkylsubstituted 2-cyclohexenonessproved incorrect. Instead, Phe and Ile replacements favored the binding of some substrates in an opposite orientation, which yielded reversed stereochemical outcomes compared to that of the wild-type OYE. For example, W116I OYE reduced (R)- and (S)-carvone to enantiomeric products, rather than the diastereomers produced by the wild-type OYE. Deuterium labeling revealed that (S)-carvone reduction by the W116I OYE occurred by the same pathway as that by the wild type (net trans-addition of H2), proving that different substrate binding orientations were responsible for the divergent products. Trp 116 mutants also afforded different stereochemical outcomes for reductions of (R)- perillaldehyde and neral. Preliminary studies of an OYE family member whosenative sequence contains Ile at position 116 (Pichia stipitis OYE 2.6) revealed that this enzyme's stereoselectivity matched that of the wild-t ype S. pastorianus OYE, showing that the identity of the residue at position 116 does not solely determine the substrate binding orientation. Computational docking studies using an induced fit methodology successfully reproduced the majority of the experimental outcomes. These computational tools will allow preliminary in silico screening of additional residues to identify those most likely to control the substrate binding orientation and provide some guidance to future experimental studies.

Opposite stereochemical courses for enzyme-mediated alkene reductions of an enantiomeric substrate pair

Rat NADP-dependent leukotriene B4 12-hydroxydehydrogenase (Ltb4dh) catalyzes olefin reductions for some activated alkenes at the expense of NADPH in the absence of a flavin cofactor. Unlike flavoprotein alkene reductases, where net trans-addition of hydrogen has been consistently observed, Ltb4dh reduced both enantiomers of perillaldehyde to the same cis-product. To uncover the reason for this unexpected result, the stereochemical courses of perillaldehyde reductions by Ltb4dh were determined by deuterium labeling followed by 2H NMR analysis. These data showed unequivocally that Ltb4dh mediated net trans-addition of hydrogen to (R)-perillaldehyde but followed the opposite stereochemical course (net syn-addition) for (S)-perillaldehyde. To the best of our knowledge, such divergent stereochemical pathways for a single enzyme have not previously been reported.

REGIOSELECTIVE CONJUGATE REDUCTION AND REDUCTIVE SILYLATION OF α,β-UNSATURATED ALDEHYDES USING 6

Regioselective conjugate reduction and reductive silylation of α,β-unsaturated aldehydes using the stable copper(I) hydride cluster, 6 is reported.The reaction is general for a range of aldehyde substitution patterns, providing the saturated aldehyde, intermediate silyl enol ether, or completely reduced alcohol in high yield, depending of reaction conditions.