A new manufacturing process for (S)-3-(aminomethyl)-5-methylhexanoic acid (Pregabalin), the active ingredient in Lyrica, has been developed. Using Lipolase, a commercially available lipase, rac-2-carboxyethyl-3-cyano-5-methylhexanoic acid ethyl ester (1) can be resolved to form 2-carboxyethyl-3-cyano-5-methylhexanoic acid (2). A heat-promoted decarboxylation of 2 efficiently generates (S)-3-cyano-5-methylhexanoic acid ethyl ester (3), a known precursor of Pregabalin. This new route dramatically improved process efficiency compared to the first-generation process by setting the stereocenter early in the synthesis and enabling the facile racemization and reuse of (R)-1. The chemoenzymatic process also reduced organic solvent usage resulting in a mostly aqueous process. Compared to the first-generation manufacturing process, the new process resulted in higher yields of pregabalin (40-45% after one recycle of (R)-1), and substantial reductions of waste streams corresponding to a 5-fold decrease in the E factor from 86 to 17.

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Monosubstituted phosphinic acids are esterified with orthosilicates in excellent yields. Phosphinylidene-containing acids react selectively under these conditions, while disubstituted phosphinic acids and phosphonic acids remain unchanged. One-pot procedures are also described for the preparation of phosphinate esters from an alcohol. This novel method provides a convenient and general alternative to more commonly employed conditions such as diazomethane or carbodiimide.

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Highly efficient stereoselective syntheses of both (Z)-and (E)-γ-bisabolenes (1) were achieved by ring closing metathesis of stereodefined tetrasubstituted alkenes. Both (Z)-and (E)-tetrasubstituted alkene precursors were obtained by Cu-catalyzed stereoselective addition of allylmagnesium

To address challenges in the preparation of a key building block containing a difluorocyclopropane moiety, we have developed a new protocol for difluorocarbene generation that relies on a Krapcho-type dealkylation of ethyl bromodifluoroacetate (EBDFA), an inexpensive and readily available fluorinated feedstock. Application of DoE and kinetic modeling was used to understand key reaction parameters and identify an optimal process. We report two variants of this procedure that offer different processing advantages and that have both been scaled successfully multiple times to deliver hundreds of kilograms of the resulting difluorocyclopropane. To access a single enantiomer of the target compound, we have also developed a classical resolution strategy and recycling protocol for the undesired enantiomer to replace previous chromatographic methods for separation.

Alternative methods for the synthesis of pyridoxine have been investigated. The key intermediate, 5-hydroxy-6-methyl-pyridine-3,4-dicarboxylic acid diethyl ester (5), was reduced with either a silane monomer (MeSiH(OEt)2) or a polysiloxane (polymethylhydrosiloxane, PMHS) to afford crude pyridoxine. An isolation technique utilizing a commercially available resin was devised, affording the desired product, vitamin B6, in an overall yield of 38-54 % and a purity of 76%.

We report in this paper on an experiment in implementing a fire spread modelling system specifically dedicated to fire-fighting activities. First, the corresponding operational framework is introduced. In particular, we stress the importance of time constraints. Then, forest fire modelling techniques as well as some considerations related to our experience and feedback on this issue are briefly tackled. Then, we bring in a model which appears as a mix between the shape approach and raster based models. This one involves both a raster representation of the landscape and an elliptical shape based approach. We conclude on the fact that the corresponding software system calculates fire contours which are correlated with actual ones provided the basic local rates of spread are accurately estimated.