Ketopantoyl lactone

Reduction of ketopantoic acid to D-pantoic acid (0, (4) in Fig. 8). Agrobacterium sp. S-246 is a good source of ketopantoic acid reductase. The yield of D-pantoic acid reached 119 g/1 (molar yield, 90% optical purity, 98% e.e.) on incubation with washed cells of the bacterium [102]. From a practical point of view, ketopantoic acid reduction with Agrobacterium cells has several advantages over ketopantoyl lactone reduction with Candida (or Rhodotorula) cells. The former results in a higher product yield, molar conversion and optical purity of the product than the latter. It is necessary to maintain the substrate level at lower than 3% in the case of the ketopantolactone reduction, but not for the ketopantoic acid reduction. 

ASYMCTRIC HYDROGENATION OF KETOPANTOYL LACTONE D-(-)-PANTOYL LACTONE... 

Ketopantoyl lactone has also been reported to be easily prepared by the oxidation of d,l-pantoyl lactone with alkaline metal hypochlorite5 or by reaction of sodium dimethylpyruvate with formaldehyde in the presence of potassium carbonate.5... 

When ketopantoyl lactone prepared by method 6b was used, the reaction was complete in 2 hr. 

Ketopantoyl lactone 2,3-Furandione, dihydro-4,4-dimethyl (8,9) (13031-04-4) D-(-)-Pantoyl lactone 2(3H)-Furanone, dihydro-3-hydroxy-4,4-dimethyl -,... 

I. Ojima, T. Kogure, and Y. Yoda 18 ASYMMETRIC HYDROGENATION OF KETOPANTOYL LACTONE D-(-)-PANTOYL LACTONE... 

Figure 19.1. Diversity of microbial reduction of ketopantoyl lactone (a) and COBE (b). A, yeasts O, molds , bacteria , actinomycetes , basidiomycetes PL, pantoyl lactone KPL, ketopantoyl lactone.

Hata, H., Shimizu, S., and Yamada, H. 1987. Enzymatic production of D-(-)-pantoyl lactone from ketopantoyl lactone. Agric. Biol. Chem., 51, 3011-3016. 

Isatin has been used in the determination of the enzymatic activity of ketopantoyl-lactone reductase587"590 and other fungal carbonyl reductases591"594, as it is a substrate of these enzymes that is reduced to a dioxindole in a reaction that can be monitored by colourimetry. Ketopantoyl-lactone reductase, also named as isatin hydrolase, can be used to remove unwanted isatin from the broth of the microbial production of indigo595 596. 

Asymmetric reduction of ketopantoyl lactone is an effective biomimetic route to R-(- )-pantolactone, an intermediate in the synthesis of the important d-( + )-pantothenic acid (a component of vitamins B and of coenzyme A) ... 

Cyclodextrin has also been used to control the enantioselectivity of bioreductions1119-1211. When added to a reaction mixture, the substrate can reside in the cyclodextrin, which decreases the effective substrate concentration around the enzyme and results in the domination of reactions involving enzymes with low KM. The effect can be demonstrated by the reduction of ketopantoyl lactone by yeast. The enantioselectivity was improved from 73% to 93% by adding p-cyclodextrin to the reaction mixture. The improvement in enantioselectivity of the reduction in the presence of enzymes with different enantioselectivities and Km values by decreasing the substrate concentration was confirmed by the ineffectiveness of a-cyclodextrin which is too small to include the substrate. It was also confirmed by dilution of the reaction mixture, which improved the enantioselectivity in the absence of cyclodextrin. 

For preparation of (i )-(-)-pantolactone the enzymic method was applied. Under the action of ketopantoyl lactone reductase in Baker s yeast (i )-(-)-pantolaetone was prepared with high chemieal and optical yields... 

Ketopantoyl lactone 2,3-Furandione, d1hydro-4,4-dlmethyl (8,9) (13031-04-4) D-(-)-Pantoyl lactone 2(3H)-Furanone, dihydro-3-hydroxy-4,4-d1methy1 0- (8) 2(3H)-Furanone, d1hydro-3-hydroxy-4,4-dimethyl- (9) (599-04-2) Ch1oro(l,5-cyclooctadiene)rhodium (I) dimer Rhodium, di-v-ch1orobis(l,5-cyclooctadiene) di- (8) Rhodium, di-y-chiorobis[(1,2,5,6- )-l,5-cyclooctadiene] di- (9) (12092-47-6)... 

Matsumoto, M. and Ito, S. (1984). Ruthenium-catalyzed Aerobic Oxidation of Pantoyl Lactone to Ketopantoyl Lactone, Synth. Commun., 14, pp. 697-700. 

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