This Review compiles the evolution, mechanistic understanding, and more recent advances in enantioselective Pd-catalyzed allylic substitution and decarboxylative and oxidative allylic substitutions. For each reaction, the catalytic data, as well as examples of their application to the synthesis of more complex molecules, are collected. Sections in which we discuss key mechanistic aspects for high selectivity and a comparison with other metals (with advantages and disadvantages) are also included. For Pd-catalyzed asymmetric allylic substitution, the catalytic data are grouped according to the type of nucleophile employed. Because of the prominent position of the use of stabilized carbon nucleophiles and heteronucleophiles, many chiral ligands have been developed. To better compare the results, they are presented grouped by ligand types. Pd-catalyzed asymmetric decarboxylative reactions are mainly promoted by PHOX or Trost ligands, which justifies organizing this section in chronological order. For asymmetric oxidative allylic substitution the results are grouped according to the type of nucleophile used.

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The completion of the Saccharomyces cerevisiae genome project in 1996 showed that almost 60% of the potential open reading frames of the genome had no experimentally determined function. Using a conserved sequence motif present in the zinc-containing mediumchain alcohol dehydrogenases, we found several potential alcohol dehydrogenase genes with no defined function. One of these, YAL060W, was overexpressed using a multicopy inducible vector, and its protein product was purified to homogeneity. The enzyme was found to be a homodimer that, in the presence of NAD ؉ , but not of NADP, could catalyze the stereospecific oxidation of (2R,3R)-2,3-butanediol (K m ‫؍‬ 14 mM, k cat ‫؍‬ 78,000 min ؊1 ) and meso-butanediol (K m ‫؍‬ 65 mM, k cat ‫؍‬ 46,000 min ؊1 ) to (3R)-acetoin and (3S)-acetoin, respectively. It was unable, however, to further oxidize these acetoins to diacetyl. In the presence of NADH, it could catalyze the stereospecific reduction of racemic acetoin ((3R/3S)-acetoin; K m ‫؍‬ 4.5 mM, k cat ‫؍‬ 98,000 min ؊1 ) to (2R,3R)-2,3-butanediol and meso-butanediol, respectively. The substrate stereospecificity was determined by analysis of products by gas-liquid chromatography. The YAL060W gene product can therefore be classified as an NAD-dependent (2R,3R)-2,3-butanediol dehydrogenase (BDH). S. cerevisiae could grow on 2,3-butanediol as the sole carbon and energy source. Under these conditions, a 3.5-fold increase in (2R,3R)-2,3-butanediol dehydrogenase activity was observed in the total cell extracts. The isoelectric focusing pattern of the induced enzyme coincided with that of the pure BDH (pI 6.9). The disruption of the YAL060W gene was not lethal for the yeast under laboratory conditions. The disrupted strain could also grow on 2,3-butanediol, although attaining a lesser cell density than the wild-type strain. Taking into consideration the substrate specificity of the YAL060W gene product, we propose the name of BDH for this gene. The corresponding enzyme is the first eukaryotic (2R,3R)-2,3-butanediol dehydrogenase characterized of the medium-chain dehydrogenase/reductase family.

A large number of therapeutic roles have been proposed for sigma(1) receptors but the involvement of sigma(1) receptor in non-acute pain had not been well explored up to now. sigma(1) receptor knock-out mice became available offering us the possibility to study the role of sigma(1) receptor in nociception, particularly in models where central sensitization processes play a significant role. Given the attractive therapeutic potential, we have developed a chemical program aimed at the discovery of novel and selective sigma(1) ligands. Herein we discuss the rational basis of this approach and report preliminary pharmacological results of several chemical series and aspects of their structure-activity relationship on sigma(1) receptor. Functional data in pain models are presented mainly on one series that provide evidence to consider selective sigma(1) receptor antagonists an innovative and alternative approach for treating neuropathic pain.