A tunable DBU/H2O medium was employed to investigate the reaction of isophorone 1 with a variety of aromatic aldehydes 2. One hour mixing of the two components in the medium at room temperature selectively afforded substitution products 3 through activation of the methyl group γ to the carbonyl functionality of isophorone. When the same mixtures were heated at 60 °C for two hours, vinylogous aldol condensation products 4 were obtained instead. This temperature-dependent reactivity demonstrates the switchable behavior of the DBU/H2O system, allowing precise control over the formation of either aldol addition or condensation products. The versatility of this approach was demonstrated by the synthesis of a wide range of derivatives, highlighting the efficiency and selectivity of this organocatalytic method. Structural characterization of the newly formed compounds was achieved by NMR spectroscopy and single-crystal X-ray diffraction, verifying the proposed molecular architectures. Overall, this work presents DBU/H2O as a simple, green, and tunable medium to control the selectivity of vinylogous aldol-type reactions in the isophorone system.

Isophorone is a relatively small molecule with several neighboring reacting sites, making it susceptible to various competing reactions with aldehydes, including aldol, Baylis-Hillman (BH), aldol condensation, and Michael addition reactions. In the present work, we have designed a switchable 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)-catalyzed procedure, where the reaction of isophorone with aldehydes is guided chemoselectively toward either aldol, BH, or aldol condensation reactions, depending on the use of water and/or heat. This controllable divergency likely stems from the ability to tune the dual nucleophilicity/basicity characters of the DBU/H2O medium. In other words, the nucleophilicity of DBU plays a crucial role in directing the process toward the formation of the BH adducts in the absence of water. At the same time, the aldol pathway dominates when water is present. The conditions were amenable for tandem processes, as demonstrated for an aldol condensation/Diels-Alder sequence.

In this work, a linear-hexaborane(8) B6(NMe2)6(CH2SiMe3)2 was synthesized using a new method. By replacing one chlorine atom of Cl2B3(NMe2)3 with CH2SiMe3 group, compound ClB3(NMe2)3CH2SiMe3 was prepared. Reductive dehalogenative coupling of ClB3(NMe2)3CH2SiMe3 led to linear-hexaborane(8). Moreover, the six-membered boron ring, cyclo-hexaborane B6(NEt2)6 was synthesized by reductive dehalogenation of Br2BNEt2. The first linear-hexaborane(8) and cyclo-hexaborane B6(NEt2)6 crystal structures were fully characterized by X-ray structural analysis and 11B, 1H, and 13C NMR spectroscopy. While the B1 & sdot;& sdot;& sdot;B6 chain in linear-hexaborane(8) is strongly twisted at all B-B bonds, the B6 ring cyclo-hexaborane B6(NEt2)6 has a chair conformation similar to cyclohexane.

Herein we present the molecular structures of six neutral Lewis acid-base adducts of the Lewis superacid Al(N(C6F5)2)3 and its higher homolog Ga(N(C6F5)2)3 with the electron pair donors MeCN, CNtBu, THF and PMe3. The crystal structures reveal crucial structural changes compared to the free Lewis acids as a consequence of the adduct formation. Furthermore, we calculated the corresponding dissociation enthalpies of the adducts which lie between 69 and 141 kJ mol-1 and are therefore considerably lower compared to the values for the formation of the anionic fluoride or chloride metallates.

An efficient synthesis of functionalized pyrido[3,2-d]pyrimidines is reported. Starting from 4-aminopyrimidine-3-carbaldehydes, a Horner-Wadsworth-Emmons olefination followed by a photoisomerization/cyclization installed the fused pyridine ring. Using substituted HWE-reagents various substituents could be introduced in the 7-position of the pyrido[3,2-d]pyrimidines. Functionalization of the pyridone substructure allowed late variation in the 6-position. In order to obtain amine-linked bis-pyridopyrimidines, 7-bromo-pyridopyrimidines were converted with their 7-amino-counterpart by Hartwig-Buchwald amination.

Metalation of the anions in the ionic liquids DMPyr[SH] and DMPyr[SeH] (DMPyr=1,1-dimethylpyrrolidinium) by trimethylgallium and trimethylindium is investigated. The reaction proceeds via pre-coordination of [EH]- , methane elimination and formation of an unprecedented series of chalcogenido metalates DMPyr2 [Me2 M(μ2 -E)]2 (M=Ga, In; E=S, Se). These show the presences of dinuclear dianions with four-membered ring structures displaying highly nucleophilic bridging chalcogenide ligands in their crystallographically determined molecular structures. Some representative reactions of these building blocks with amphoteric electrophiles were studied: Addition of two equivalents of E(SiMe3 )2 (E=S, Se) to the indates DMPyr2 [Me2 In(μ2 -S)]2 and DMPyr2 [Me2 In(μ2 -Se)]2 leads to a cleavage of the ring, E silylation and formation of mononuclear, monoanionic indates DMPyr[Me2 In(SSiMe3 )2 ], DMPyr[Me2 In(SeSiMe3 )2 ], and even a mixed sulfido-selenido dimethylindate DMPyr[Me2 In(SSiMe3 )(SeSiMe3 )]. Reaction of DMPyr2 [Me2 In(μ2 -S)]2 with two equivalents of Lewis acid Me3 In leads to charge delocalization, ring expansion and formation of six-membered ring DMPyr3 [Me2 In(μ2 -S-InMe3 )]3 . The latter is a key intermediate in the formation of dianionic sulfidoindate DMPyr2 [(Me2 In)6 (μ3 -S)4 ] displaying an unusual inverse heteroadamantane cage structure with four capping sulfido ligands.

A new class of bis-cyclometalated iridium(III) catalysts containing two inert cyclometalated 6-tert-butyl-2-phenyl-2H-indazole bidentate ligands or two inert cyclometalated 5-tert-butyl-1-methyl-2-phenylbenzimidazoles is introduced. The coordination sphere is complemented by two labile acetonitriles, and a hexafluorophosphate ion serves as a counterion for the monocationic complexes. Single enantiomers of the chiral-at-iridium complexes (>99% er) are obtained through a chiral-auxiliary-mediated approach using a monofluorinated salicyloxazoline and are investigated as catalysts in the enantioselective conjugate addition of indole to an α,β-unsaturated 2-acyl imidazole and an asymmetric Nazarov cyclization.

A diastereoselective and enantioselective construction of 2,3-disubstituted 1,4-dicarbonyl compounds is reported. Nishiyama's RuPhebox complex (2.0 mol% catalyst loading) serves as a chiral Lewis acid catalyst in conjunction with BrCC1 3 and a base for the oxidative homocoupling of 2-acyl imidazoles via the stereocontrolled reaction of intermediate Ru enolates with in situ brominated 2-acyl imidazoles. Cleavage of the achiral imidazole auxiliary provides optically active 2,3-disubstituted succinic acids which are useful intermediates in the synthesis of chiral compounds like the natural product class of lignans.

The synthesis of 2,9-diaza-1,3,8,10-tetratriflato-dibenzoperylene (DDP 3 a) and corresponding 2,9-dimethyl-1,3,8,10-tetratriflato-dibenzoperylene (DBP 3 b) has been developed at multigram scale via reduction of one of the industrially most important high-performance dyes, perylene-3,4,9,10-tetracarboxylic diimide (PTCDI), and of the corresponding dihydroxy peropyrenequinone precursor. The focus of this paper is on the reactivity pattern of 3 a as key intermediate towards highly functionalized 2,9-diazadibenzopyrelenes (DDPs) obtained via catalytic substitution of four triflate by aryl, heteroaryl, alkynyl, aminyl, and O-phosphanyl substituents. The influence of electron-donating substituents (OSiMe3, OPt-Bu-2, N-piperidinyl), electron-withdrawing (OTf, 3,5-bis-trifluoromethyl-phenyl), and of electron-rich pi-conjugated (2-thienyl, 4-tert-butylphenyl, trimethylsilyl-ethynyl) substituents on optoelectronic and structural properties of these functionalized DDPs has been investigated via XRD analyses, UV/Vis, PL spectroscopy, and by electroanalytical CV. These results were correlated to results of DFT and TD-DFT calculations. Thus, functionalized DPPs with easily tunable HOMO and LUMO energies and gap became available via a new and reliable synthetic strategy starting from readily available PTCDI.

A ring-closing aminooxygenation of alkenes with N-benzoyloxycarbamates occurs with very high diastereoselectivity (typically >20:1 d.r.) and very high enantioselectivity (up to 99% ee). The reaction is catalyzed by a recently developed chiral-at-metal ruthenium complex at catalyst loadings of 0.5-1.0 mol %. The reaction is proposed to proceed through a ruthenium nitrenoid intermediate that depending on the nature of the substrate undergoes either an aminooxygenation (1,2-disubstituted alkenes) or stops at the stage of the aziridination (trisubstituted alkenes), which can then be ring opened with benzoic acid. The resulting chiral cyclic carbamates can be hydrolyzed under basic conditions to provide versatile chiral 2-amino-1,3-diols with vicinal stereocenters.

The title crystal structure is assembled from the superposition of two molecular structures, ( E )-1-(5-chlorothiophen-2-yl)-3-(3-methylthiophen-2-yl)prop-2-en-1-one, C 12 H 9 ClOS 2 (93%), and ( Z )-1-(5-chlorothiophen-2-yl)-3-(3-methylthiophen-2-yl)prop-1-en-1-ol, C 12 H 11 ClOS 2 (7%), 0.93C 12 H 9 ClOS 2 ·0.07C 12 H 11 ClOS 2 . Both were obtained from the reaction of 3-methylthiophene-2-carbaldehyde and 1-(5-chlorothiophen-2-yl)ethanone. In the extended structure of the major chalcone component, molecules are linked by a combination of C—H...O/S, Cl...Cl, Cl...π and π–π interactions, leading to a compact three-dimensional supramolecular assembly.

An enantioselective total synthesis of the natural product (-)-preussochromone A is reported. The tricyclic thiopyrane skeleton could be assembled via Lewis acid-mediated cycloisomerization of a precursor with a 2-thiochromenone substructure and an α-ketoester moiety. The chromenone core was synthesized by cyclization of a dithioketene acetal and oxidation to a 2-sulfonylchromenone to set up the subsequent thia-Michael-retro-Michael addition of an aliphatic thiol producing the highly oxidized side chain.

A hetero-dinuclear cobalt(iii)/sodium complex has been synthesized and characterized. The complex which has been used to construct photosensitive Schottky devices, shows interesting C–H⋯π(N3) interactions in the solid state.