Les Cetotheriidae (Mammalia, Cetacea, Mysticeti) de la Formation Pisco (Miocène inférieur Pliocène inférieur) de la côte péruvienne. Relations phylogénétiques et affinités des Cetotheriidae

Les mysticètes à fanons comprennent généralement quatre familles actuelles et une famille fossile: les Cetotheriidae s.l. Dépourvus des synapomorphies des mysticètes actuels, ces fossiles sont un groupe paraphylétique peu étudié. La description de trois nouveaux taxons fossiles (Piscobalaena nana et deux nouveaux genres) de la Formation Pisco (Néogène, Pérou) a mis en évidence de nouveaux caractères morphologiques. Les Balaenopteridae ont une stratégie de nutrition très particulière à laquelle sont associés des caractères morphologiques du crâne et du dentaire. Six taxons fossiles présentent certains de ces caractères. Ils pourraient donc être phylogénétiquement proches des ces derniers et avoir utilisé la même stratégie nutritionnelle. L'analyse cladistique de 54 caractères (crâne, région auditive et dentaire) de 25 taxons suggère que huit des 15 taxons fossiles étudiés forment un clade : les Cetotheriidae s.s. Son groupe-frère comprend les taxons actuels et cinq fossiles.Baleen mysticetes traditionally comprise four living families and a fifth exclusively fossil family: the Cetotheriidae s.l.. New material (Piscobalaena nana and two new genera) from the Neogene Pisco Formation of Peru, yield new morphological data. Balaenopteridae have a peculiar feeding behaviour associated with some morphological characters of the skull and dentary. Six fossil taxa present similar morphologies. Thus they could be phylogenetically close to Balaenopteridae and could have used the same feeding behaviour. The cladistic analysis of 54 characters (skull, auditory area, dentary) of 25 taxa suggests that eight of the 15 studied Cetotheriidae s.l. constitute a clade: the Cetotheriidae s.s. Its sister-group includes the extant taxa and five fossil taxa.PARIS-Museum Hist.Naturelle (751052304) / SudocSudocFranceF

Data on synthesis of oligomeric and polymeric poly(butylene adipate-co-butylene terephthalate) model substrates for the investigation of enzymatic hydrolysis

The aliphatic-aromatic copolyester poly(butylene adipate-co-butylene terephthalate) (PBAT), also known as ecoflex, contains adipic acid, 1,4-butanediol and terephthalic acid and is proven to be compostable [1–3]). We describe here data for the synthesis and analysis of poly(butylene adipate-co-butylene terephthalate variants with different adipic acid:terephatalic acid ratios and 6 oligomeric PBAT model substrates. Data for the synthesis of the following oligomeric model substrates are described: mono(4-hydroxybutyl) terephthalate (BTa), bis(4-(hexanoyloxy)butyl) terephthalate (HaBTaBHa), bis(4-(decanoyloxy)butyl) terephthalate (DaBTaBDa), bis(4-(tetradecanoyloxy)butyl) terephthalate (TdaBTaBTda), bis(4-hydroxyhexyl) terephthalate (HTaH) and bis(4-(benzoyloxy)butyl) terephthalate (BaBTaBBa). Polymeric PBAT variants were synthesized with adipic acid:terephatalic acid ratios of 100:0, 90:10, 80:20, 70:30, 60:40 and 50:50. These polymeric and oligomeric substances were used as ecoflex model substrates in enzymatic hydrolysis experiments in the article “Substrate specificities of cutinases on aliphatic-aromatic polyesters and on their model substrates” [4]. Keywords: Oligomer synthesis, Oligomer analysis, Polyester model substrate

Total Synthesis of Myxovirescin A₁

A convergent total synthesis of the antibiotic macrolide myxovirescin A1 (1) is described that is largely based on reagent- and catalyst-controlled transformations. This includes a highly regioselective Negishi reaction of dibromo-alkene 48 with an alkynylzinc reagent, and a palladium catalyzed alkyl-Suzuki coupling of the resulting enyne derivative 12 with the 9-BBN-adduct derived from alkene 61. The latter was obtained via an asymmetric hydrogenation of the chlorinated β-ketoester 49 and an anti-selective oxyallylation of the functionalized aldehyde 53 as the key steps. The preparation of the bis-borylated allyl-donor 57 used in the oxyallylation step, however, required careful optimization and led to important insights into the nature of the classical hydroborating agent “di(isopinocampheyl)borane (Ipc2BH)”. It was unambiguously shown by X-ray crystallography that in the solid state this compound is dimeric, but it is prone to undergo an essentially quantitative mono-deborylation when dissolved in CH2Cl2 or benzene; its composition in ethereal solvents is even more complex as evident from 11B NMR data. Product 71 derived from 12 and 61 was elaborated into the enyne–yne derivative 75, which served as the substrate for an exquisitely selective ring closing alkyne metathesis reaction (RCAM) catalyzed by the molybdenum tris-amido complex 20 activated in situ with CH2Cl2. The resulting cyclic enyne 76 was subjected to a ruthenium catalyzed trans-hydrosilylation/proto-desilylation tandem. Although [Cp*Ru(MeCN)6]PF1 had previously been recommended as catalyst of choice for trans-hydrosilylation reactions of internal alkynes, this complex failed to afford the desired product, whereas its sterically less hindered congener [CpRu(MeCN)3]PF6 permitted the reaction to be performed in appreciable yield, but at the expense of a lower stereoselectivity. AgF-mediated proto-desilylation of the isomeric silanes 79 and 80 followed by cleavage of the remaining acetal protecting groups afforded myxovirescin A1 and its hitherto unknown 14Z-isomer 81, respectively