Hydrothermal reduction of CO 2 using Zn as reductant to obtain formic acid is a selective and efficient process. This process has the advantage of avoiding the use of gaseous hydrogen with all its safety and environmental concerns, and allowing an easier integration with CO 2 capturing steps such as CO 2 absorption in aqueous NaOH, because the latter solutions can be directly fed to the process as NaHCO 3. In this work, this reaction was studied in batch reactors at temperatures from 275 to 325ºC. Conversions up to 75% were obtained with selectivity towards formic acid near 100%, at residence times between 10 and 180 min. Reactions proceeds fast in the first steps of reaction, and it is slowed down when the oxidation of Zn is completed. The experimental results obtained were used to stablish a model that can explain both experimental data from this work and from literature with an averaged error of 13%. Using both the model and the experimental data the main variables of the process were analyzed: temperature, Zn/HCO 3 ratio, heating rate, Zn particle size, pressure reactor material and use of supercritical conditions. The optimum reaction conditions found were 300ºC with a rapid heating, and particle sizes of 0.75-1 mm. Zn excess dramatically improves the yield, but working with a lower excess can be compensated by working at pressures higher than 300 bar.

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The regio‐ and stereo‐selective ring opening of (S)‐pyroglutaminol derived epoxides provides an effective route to protected syn,syn‐aminodiol units. The procedure involves the chemoselective aminolysis or alcoholysis of (3R,4R,5R)‐N‐(tert‐butoxycarbonyl)‐3,4‐epoxy‐5‐[(1‐ethoxy)ethoxymethyl]pyrrolidin‐2‐one (10), followed by the formation in quantitative yield of oxazolidinone intermediates, through the mediation of neighbouring N‐Boc groups. The practical synthetic interest of this route is illustrated by the example of (3R,4S,5R)‐3,4‐diacetoxy‐5‐(acetoxymethyl)pyrrolidin‐2‐one which should serve as useful building block in further syntheses.

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