1 2 4 Butanetriol World Production

Scheme 2.14 Readily accessible five-carbon building blocks from D-xylose.

Another entry into useful five-carbon building blocks from d-xylose encompasses the expeditious four-step protocol for the 1-phenylpyrazol-3-carboxaldehyde with a 5-hydroxymethyl substituent (Scheme 2.15) and the various follow-up reactions feasible.104,105

d-Xylose

PhNHNH,

OH NNHPh

AC2O/A

HO OH NNHPh

CH,0/lf

AcPh

AcPh

BaMnOi

NH3 Ni/H2

NH3 Ni/H2

BaMnOi

NH3, Ni/H2

NH3, Ni/H2

Scheme 2.15 Useful five-carbon building blocks from D-xylose.

Aside from the multifaceted chemical conversions, there are sources to develop into industrially viable microbial conversions. 1,2,4-Butanetriol, for example, used as an intermediate chemical for alkyd resins and rocket fuels, is currently prepared commercially from malic acid by high-pressure hydrogenation or hydride reduction of its methyl ester. In a novel environmentally benign approach to this chemical, wood-derived d-xylose is microbially oxidized to d-xylonic acid, followed by a multistep conversion to the product effected by a biocatalyst specially engineered by inserting Pseudomonas putida plasmids into E. coli:106

OH OH

OH OH

frag'

OH O

d-Xylose

OH OH

OH O

d-Xylonic acid

OH O

d-Xylonic acid

Although further metabolic engineering is required to increase product concentration and yields, the microbial generation of 1,2,4-butanetriol is a clear alternative to its acquisition by chemical procedures.

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  • Rhoda
    How to oxidize xylose to make xylonic acid?
    9 years ago

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