SUMMARYMost commonly studied bacteria grow symmetrically and divide by binary fission, generating two siblings of equal morphology. An exception to this rule are budding bacteria, in which new offspring emerges de novo from a morphologically invariant mother cell. Although this mode of proliferation is widespread in diverse bacterial lineages, the underlying mechanisms are still incompletely understood.Here, we perform the first molecular-level analysis of growth and morphogenesis in the stalked budding alphaproteobacterium Hyphomonas neptunium. Peptidoglycan labeling shows that, in this species, buds originate from a stalk-like extension of the mother cell whose terminal segment is gradually remodeled into a new cell compartment. As a first step toward identifying the machinery mediating the budding process, we performed comprehensive mutational and localization studies of predicted peptidoglycan biosynthetic proteins in H. neptunium. These analyses identify factors that localize to distinct zones of dispersed and zonal growth, and they suggest a critical role of the MreB-controlled elongasome in cell morphogenesis. Collectively, our work shows that the mechanism of growth in H. neptunium is distinct from that in related, polarly growing members of the order Rhizobiales, setting the stage for in-depth analyses of the molecular principles regulating the fascinating developmental cycle of this species.

Keywords: Tellurium / Ligand design / Palladium / Platinum / Mercury / Solid-state structures N-[3-(Phenyltellanyl)propyl]picolinamide (HL1) or N-[NЈЈ,NЈЈ-methyl(phenyl)aminothiocarbonyl]-NЈ-[3-(phenyltellanyl)propyl]benzamidine (HL2) react with equivalent amounts of PtCl 2 or PdCl 2 with formation of neutral [MCl(L1-κN,NЈ,Te)] or [MCl(L2-κS,N,Te)] chelates. A corresponding reaction of HL2 with HgCl 2 results in the formation of [HgCl 2 (HL2-κS,Te)]. Treatment of [PtCl(L1-N,NЈ,Te)] with elemental iodine results in the exclusive oxidation of the metal [a] Scheme 2. Synthesis of HL1 and HL2.Both products were obtained as viscous oils, which could not be solidified even after several chromatographic purifi-Eur.

Due to their high density of functional groups, vicinal tricarbonyl compounds are versatile building blocks for the synthesis of complex target molecules. Methods for their preparation and their use in stereoselective CC bond formations, as well as for the synthesis of heteroaromatics, are summarised for the period 2006-2016. Several examples for their applications in natural product synthesis (awajanomycin, cladoniamide, wailupemycin) are presented. 1 Introduction 2 Preparation of Vicinal Tricarbonyl Compounds 3 Use in Stereoselective CC Bond Formations 4 Use for the Synthesis of Heteroaromatics 5 Examples from Natural Product Synthesis 6 Conclusion Key words vicinal tricarbonyl compounds, stereoselective synthesis, natural products, total synthesis, regioselectivity Lars Selter (from left to right) was born in Berlin, Germany in 1989. He studied chemistry at the Freie Universität Berlin and received his B.Sc. degree in 2011 and his M.Sc. degree in 2013 under the supervision of Prof. H.-U. Reißig. Currently, he is working as a Ph.D. student at the Philipps-Universität Marburg under the guidance of Prof. U. Koert focusing on regioselective CC bond formation on vicinal tricarbonyl compounds. Lukas Zygalski was born in Rotenburg/Fulda, Germany in 1990. He completed his B.Sc. degree in 2013 and his M.Sc. degree (specialisation in organic chemistry) in 2016 under the supervision of Prof. U. Koert at the Philipps-Universität Marburg. Currently, he is working there as a Ph.D. student focusing on natural product synthesis. Eric Kerste was born in Rotenburg/Fulda, Germany in 1990. He completed his B.Sc. degree in 2013 and his M.Sc. degree (specialisation in organic chemistry) in 2016, both under the supervision of Prof. U. Koert at the Philipps-Universität Marburg. Currently, he is working there as a Ph.D. student focusing on natural product synthesis based on vicinal diketo esters. Ulrich Koert was born in Hanau, Germany in 1961. He studied chemistry at the Goethe Universität in Frankfurt where he obtained his Ph.D. in

Methods for the regioselective alkylation, arylation, and alkenylation of α,β‐diketo esters using organozinc reagents are reported. Alkylation and arylation at the α‐position is possible using diorganozinc compounds. Alkenylation can be achieved using mixed (alkenyl)dineopentylzincates.

The optimized coupling of N-protected (S)-proline and (2S,4R)-4-hydroxyproline derivatives with (Z)-4-aminopent-3-en-2-one provided the expected β-ketoenamides in good to excellent yields. The subsequent intramolecular cyclizations afforded enantiopure pyridin-4-one derivatives with pyrrolidin-2-yl substituents. The nonaflates generated from these intermediates were excellent precursors for typical palladium-catalyzed coupling reactions. Oxidation with m-chloroperbenzoic acid gave pyrrolidine N-oxides whose subsequent reactions were inves-tigated. The condensation of β-ketoenamides with hydroxylamine hydrochloride furnished the corresponding enantiopure pyrimidine N-oxides in good yields. The subsequent Boekelheide rearrangement provided hydroxymethyl-substituted pyrimidine derivatives together with minor components. Overall, this study nicely demonstrates the potential of (S)-proline-or (2S,4R)-4-hydroxyproline-derived β-ketoenamides to approach a library of novel chiral pool-derived enantiopure functionalized pyridine and pyrimidine derivatives.