The use of electricity over traditional stoichiometric oxidants is a promising strategy for sustainable molecular assembly. Herein, we describe the rhoda-electrocatalyzed CÀ H activation/alkylation of several N-heteroarenes. This catalytic approach has been successfully applied to several arenes, including biologically relevant purines, diazepam, and amino acids. The versatile CÀ H alkylation featured water as a co-solvent and user-friendly trifluoroborates as alkylating agents. Finally, the rhoda-electrocatalysis with unsaturated organotrifluoroborates proceeded by paired electrolysis.

While electrochemical ortho-selective CÀ H activations are well established, distal CÀ H activations continue to be underdeveloped. In contrast, we herein describe the electrochemical meta-CÀ H functionalization. The remote CÀ H bromination was accomplished in an undivided cell by RuCl 3 •3 H 2 O with aqueous HBr. The electrohalogenation proceeded under exogenous ligand-and electrolyte-free conditions. Notably, pyrazolylarenes were meta-selectively brominated at the benzenoid moiety, rather than on the electron-rich pyrazole ring for the first time. Mechanistic studies were suggestive of an initial ruthenacycle formation, and a subsequent ligand-to-ligand hydrogen transfer (LLHT) process to liberate the brominated product.

Thirteen strains of the gram-negative, facultative phototrophic bacterium Rhodobacter sphaeroides were examined for susceptibility to ,-lactam antibiotics. All strains were sensitive to the semisynthetic penicillins ampiciflin, carbenicillin, oxacillin, cloxacillin, and methicillin, but 10 of the 13 strains were resistant to penicillin G, as well as a number of cephalosporins, such as cephalothin, cephapirin, and cephalosporin C. A ,1-lactamase (EC 3.5.2.6) with strong cephalosporinase activity was detected in all of the resistant strains of R. sphaeroides. With strain Y-1 as a model, it was shown that the (-lactamase was inducible by penicillin G, cephalosporin C, cephalothin, and to some minor extent, cephapirin. The j-lactamase was located in the periplasmic space, from which it could be extracted by osmotic shock disruption. By using this fraction, the j-lactamase was purified 34-fold to homogeneity by steps involving batch adsorption to and elution from DEAE-Sephadex A50, chromatography on Q-Sepharose, and preparative polyacrylamide gel electrophoresis. The molecular masses of the native and denatured enzymes were determined to be 38.5 kilodaltons by gel filtration and 40.5 kilodaltons by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, respectively, indicating a monomeric structure. The isoelectric point was estimated to be at pH 4.3. In Tris hydrochloride buffer, optimum enzyme activity was measured at pH 8.A. The j8-lactamase showed high activity in the presence of the substrates cephalothin, cephapirin, cephalosporin C, and penicillin G, for which the apparent Km values were 144, 100, 65, and 110 ,iM, respectively. Cephalexin, cepharidine, and cephaloridine were poor substrates. The j-lactamase was strongly inhibited by cloxacillin and oxacillin but only slightly inhibited by phenylmethylsulfonyl fluoride or thiol reagents such as iodoacetate and p-chloromercuribenzoate.Bacterial resistance to penicillins or cephalosporins is associated primarily with the formation of 13-lactamases (EC 3.5.2.6) (18). Although strains of the facultative phototrophic bacterium Rhodobacter sphaeroides have been reported to be remarkably resistant to penicillin, as well as a number of semisynthetic penicillins (14,16,17), the enzymes that mediate such resistances in photosynthetic bacteria have not been studied. Only penicillin-binding proteins of R. sphaeroides 2.4.1 have been characterized in terms of size and cellular localization (22).In the present communication, we show that most of our R. sphaeroides wild-type iso-lates were resistant to penicillin and a number of cephalosporins but not to semisynthetic penicillins. Resistance was associated with a periplasmic P-lactamase whose isolation from a phototrophic bacterium and characterization are reported for the first time. MATERIALS AND METHODSBacterial strains. R. sphaeroides is a purple nonsulfur bacterium. Strains DSM 158 (identical to ATCC 17023, NCIB 8253, and ATH 2.4.1), DSM 159 (1760-1), and DSM 160 (Y) were obtained from the German Collection of Microo...

Beim oxydativen Abbau mit Kaliumpermanganat wurde aus (+)‐Cyclolavandulol eine Carbonylverbindung erhalten, welche nach der Analyse des Semicarbazons die Bruttoformel C10H16O3 besitzt.

Lavandulol, ein vor einigen Jahren aus dem 61 von Lavandula vera isolierter Monoterpenalkohol2) der Formel 113) ist dem schon vie1 langer bekannten und starker verbreiteten Geraniol (1) in mancher Beziehung sehr iihnlich. Da auch die N, @-Dihydroverbindung des Geraniols, das Citronellol (111), ein wichtiger Bestandteil vieler atherischer Ole ist, war es von Interesse, auch ein Hydrolavandulol darzustellen, in welchem die der Hydroxylgruppe naherliegende, d. h. in diesem Falle / I , y-standige Doppelbindung abgessttigt ist. Ein solcher Alkohol wurde die Konstitution entsprechend Formel IV besitzen. 1) Siehe auch die demniichst im Druck erscheinenden Dissertationen von H . L. Bimon und Ad. K a u f m n n . 2) H. Schinz und C. F. Seidel, Helv. 25, 1572 (1942). Der gleiche Alkohol wurde spater von Y. R. Naves, Helv. 28,1220 (1945) im 61 des sogenannten ,,Lavandin", einem Bastard von Lavendel und Spik, nachgewiesen. 3, H . Schinz und J.-P. Bourquin, Helv. 25, 1591 (1942).