Sphingomonas sp HXN

Figure 15.2 Improvement of the hydroxylation activity and enantioselectivity with Sphingomonas sp. HXN-200 hy substrate modification.

Sphingomonas sp. HXN-200 was also able to accept a six-member ring substrate. Hydroxylation of A/-benzyl- and A/-/ert-butoxycarbonyl-2-piperidinone gave the corresponding (/J)-4-hydroxy-piperidin-2-ones in 31% and 68% ee, respectively (Figure 15.4). This provides a simple synthesis of such types of useful synthons. 

To facilitate its application in organic synthesis, we developed a lyophilized cell powder of Sphingomonas sp. HXN-200 as a biohydroxylation catalyst. Hydro-xylation of A-benzyl-piperidine with such catalyst powder showed 85% of the activity of a similar hydroxylation with frozen/thawed cells, shown in Figure 15.6. The fact that rehydrated lyophilized cells are able to carry out such a reduced nicotinamide adenine dinucleotide (NADH)-dependent hydroxylation indicates that these cells are capable of retaining and regenerating NADH at rates equal to or exceeding the rate of hydroxylation. To our knowledge, this is the first example of the use of lyophilized cells for a cofactor-dependent hydroxylation. 

Figure 15.6 Hydroxylation of iV-benzylpiperidine (5 mM) with lyophilized cell powder and frozen/thawed cells of Sphingomonas sp. HXN-200 at cell concentration of 4.0 g cdw/L.

Hydroxylation of azetidine-l-carboxylates 33 with a biocatalyst, Sphingomonas sp. HXN-200, gave the corresponding 3-hydroxyazetidines 34 (Equation 7) <20020L1859>. 

Figure 4. Hydroxylation of N-substituted pyrrolidines by Sphingomonas sp. HXN-200. indicates the introduction of a chiral center. R = CH2Ph, COPh, C02CH2Ph, C02Ph, C02Ph,...

Chang, D., Feiten, H.-J., Witholt, B., and li, Z. (2002) Regio- and stereoselective hydroxylation of N-substituted piperidin-2-ones with Sphingomonas sp. HXN-200. Tetrahedron Asyrmnetry, 13 (19), 2141-2147. 

An excellent example of this is provided by cytochrome P450, an enzyme from Sphingomonas sp. HXN-200, which was shown to have good hydroxylation activity toward substrates such as N-benzyl heterocycles and terpenes in the wild-type strain [30,31 ]. One major disadvantage of the Sphingomonas is that it needs to be grown on the flammable hydrocarbon octane as the sole carbon source in order to induce expression of the P450 enzyme. 

Enantioselective hydrolysis of styrene epoxides 38 by two different epoxide hydroiases from Sphingomonas sp. HXN-200 (SpEH) and S. tuberosum (StEH) [74]. 

Enantioselective hydrolysis of cyclohexene oxide 37 using epoxide hydrolase SpEH from Sphingomonas sp. HXN-200 in f. colion multigram scale [72]. 

Li and coworkers have described the gram-scale preparative desymmetrization of cyclohexene oxide, cyclopentene oxide, and N-benzyloxycarbonyl-3,4-epoxypyr-rolidine using the EH from Sphingomonas sp. HXN-200 expressed in the recombinant host E. coli (SpEH) [94]. Desymmetrization of 10 g of cyclohexene oxide (500 mM substrate concentration) with resting cells of E. coli (SpEH) (10 g cdw/1) afforded 10.3 g (89% isolated yield) of (lE,2R)-l,2-cyclohexanediol in 86% ee. Desymmetrization of the two other meso-epoxides (200 mM substrate concentration) afforded (1R,2R)-1,2-cyclopentanediol in 87% ee and 70.4% isolated yield and (3R,4R)-N-benzyloxy-carbonyl-3,4-dihydroxypyrrolidine in 93% ee and 94.1% isolated yield, respectively. 

Wu, S., Li, A., Chin, Y.S. and Li, Z. (2013) Enantioselective hydrolysis of racemic and ffxeso-epoxides with recombinant Escherichia colt expressing epoxide hydrolase from Sphingomonas sp. HXN-200 preparation of epoxides and vicinal diols in high ee and high concentration. ACS Catal., 3, 752-759. 

Chang, D., Wang, Z., Heringa, M.R, Wirthner, R., Witholt, B. and Li, Z. (2003) Highly enantioselective hydrolysis of alicyclic meso-epoxides with a bacterial epoxide hydrolase from Sphingomonas sp. HXN-200 simple synthesis of alicyclic vicinal frans-diols. Chem. Commun., 960-961. 

P450py from Sphingomonas sp. HXN-200 Iterative saturation mutagenesis HPLC Activities toward p-substituted styrene increased up to 3-fold [33,134]... 

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