Lactones, hydrogenation

This enzyme [EC 1.1.3.4] catalyzes the following reaction /3-o-glucose + 02 o-glucono-1,5-lactone + hydrogen peroxide. 

In another process, 13-oxabicyclo[10.4.0]hexadec-l(12)-ene is reacted with isopropyl nitrite to give 12-oxo-15-pentadecanolide, which is hydrogenated to the corresponding hydroxy compound. The hydroxy group is derivatized and the reaction product py roly zed to the unsaturated lactone. Hydrogenation of the latter yields 15-pentadecanolide [204]. 

A second synthesis of cordrastine starts from a Reissert compound, the 6,7-dimethoxy-analogue of (9), which was condensed with 2-methoxycarbonyl-3,4-dimethoxybenzaldehyde the product was hydrolysed, lactonized, hydrogenated, and N-methylated.118... 

Among the hydrogenation, hydroamination, hydroformylation, and oxidation of 6-lactones, hydrogenation is of particular interest owing to its facile approach to a... 

Kuen has shown that gases from Fenton reagent-carbohydrate systems consist almost entirely of carbon dioxide. This fact has been exploited for simple, manometric studies of the iron (III) chloride-D-glucono-1,5-lactone-hydrogen peroxide reaction. Equivalent dismutation between carbohydrate fragments, or reduction of carbon dioxide to formic acid, have been suggested in order to account for the deficit (about 66%) in carbon dioxide arising from the oxidative scission. ... 

FIGURE 4.4 The glucose oxidase reaction P-D-glucose + oxygen and its products D-glucono-1,5-lactone+ hydrogen peroxide. 

Fig. 13-21 Lactone hydrogenation in a trickie-bed reactor conversion profiies as a function of iiquid flow at constant iiquid hoidup [19]...

Fig. 13-22 Lactone hydrogenation in a trickle-bed reactor conversion profiles taking into account the external liquid holdup [19]...

This oxidative process has been successful with ketones,esters, and lactones. Hydrogen peroxide can also be used as the oxidant, in which case the alcohol is formed directly. The mechanism for the oxidation of enolates by oxygen is a radical-chain autoxidation in which the propagation step involves electron transfer fix)m the carbanion to... 

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