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A new method for the decarboxylative coupling of alkyl N-hydroxyphthalimide esters (NHP esters) with aryl iodides is presented. In contrast to previous studies that form alkyl radicals from carboxylic acid derivatives, no photocatalyst, light, or arylmetal reagent is needed, only nickel and a reducing agent (Zn). Methyl, primary, and secondary alkyl groups can all be coupled in good yield (77% ave yield). One coupling with an acid chloride is also presented. Stoichiometric reactions of (dtbbpy)Ni(2-tolyl)I with an NHP ester show for the first time that arylnickel(II) complexes can directly react with NHP esters to form alkylated arenes.

Enantiomerically pure β-amino alcohols undergo Ugi reactions under classic or Lewis-acid-promoted conditions to give polyfunctionalized peptidomimetics with moderate to good diastereoselectivities.

The application of an iridium-catalyzed hydrogen borrowing process to enable the formation of α-branched ketones with higher alcohols is described. In order to facilitate this reaction, ortho-disubstituted phenyl and cyclopropyl ketones were recognized as crucial structural motifs for C–C bond formation. Having optimized the key catalysis step, the ortho-disubstituted phenyl products could be further manipulated by a retro-Friedel–Crafts acylation reaction to produce synthetically useful carboxylic acid derivatives. In contrast, the cyclopropyl ketones underwent homoconjugate addition with several nucleophiles to provide further functionalized branched ketone products.

Aryl and alkyl CF3 groups are converted into CH2-aryl fragments upon treatment with arenes in the presence of the reagents/catalyst combination under conditions A).

The hydrogenation of olefins is achieved using a combination of phoshorous(V)-based Lewis acids with diaryl amines for the activation of dihydrogen.

The allylation of stable, protected imine precursors, α-amido sulfones, with allylic acetates to form homoallylic amines is catalyzed by nickel under mild reducing conditions. Aliphatic and aryl imines are tolerated, as are substituted allylic acetates. In the case of substituted allylic acetates, high diastereoselectivity and regioselectivity is observed in some cases and the branched product is obtained almost exclusively.

In addition to the hydrosilylation reaction, the catalyst can also be used for the isomerization of alkenes under similar conditions (without a silane), e.g. 1-hexene is isomerized to an E/Z mixture of 2-hexene along with small amounts of polymerization products.

Rational selection of molecular precursors is the key consideration in the synthesis of inorganic nanocrystals and nanoparticles. This review highlights the state-of-the-art and future potential of metal amides as precursors in the solution-phase synthesis of monodisperse colloidal nanocrystals of metals and metal alloys, as well as metal oxides and chalcogenides. We exclusively focus on homoleptic metal and metalloid alkylamides M(NR2)n and silylamides M[N(SiMe3)2]n as predominant choice of element-nitrogen bonded precursors, which are often advantageous to commonly used metal–oxygen and metal–carbon bonded counterparts. In particular, these amides are highly reactive in oxidation, reduction and metathesis reactions; they are oxygen-free, easy-to-make and/or commercially available. A comprehensive literature review is complemented by our theoretical studies on the thermal stability of metal silylamides using molecular dynamics simulations.

Both α- and β-LiFePO4 are synthesized from solutions of LiCl, Fe(OAc)2, and H3PO4 in a mixture of benzyl alcohol and 2-pyrrolidinone in the ratios 4:1 and 1:1, respectively (microwave irradiation, 195 °C, 3 min).

The major theme of this review concerns the reaction pathways of heavier main group 13 dimetallenes with olefins, cyclic olefins, polyolefins, other unsaturated molecules, and hydrogen. For gallium derivatives, these reactions proceed readily in high yield under ambient conditions. Early investigations showed that the group 13 dimetallenes dissociated to one-coordinate metallanediyl monomers, which suggested that they reacted as monomeric species due to their more open, less hindered structures. However, recent DFT calculations by Tuononen and co-workers show that the reaction of the monomers with olefins or hydrogen involves very large energy barriers and that the dimetallenes react instead as undissociated dimers. In contrast to the corresponding all-carbon systems, where [2 + 2] cycloadditions are forbidden because of π–π* symmetry mismatch, the dimetallenes react with olefins via two stepwise, symmetry-allowed [2 + 2] cycloadditions to give 1,4-digallacyclohexanes. The addition of the H2 proceeds by a...

The reaction of anhydrous THF and pentane dispersions of NaBH4 and NiBr2 of different concentrations (2.52, 5.46, 7.37, and 10.18 mol%) at room temperature and pressure yield amorphous black solid powders of nickel borides.

N-Acetyl-1,3-thiazolidine derivatives of cyclohexanones, when treated with a threefold excess N-bromosuccinimide in anhydrous chloroform at room temperature, smoothly afford N-acetyl-2,3-dihydro-1,4-benzothiazines. This represents the first general route to such heterocyclic system in one step from aliphatic precursors. The synthesis of optically active N-acetyl-2,3-dihydro-1,4-benzothiazines is also reported

γ-Methylene derivatives of α,β-unsaturated ketones are obtained readily by a one-pot procedure exploiting the reaction of O-silylated dienolates with commercially available formaldehyde N, N-dimethyliminium chloride in anhydrous N, N-dimethylformamide, in situ oxidation of the Mannich reaction product with hydrogen peroxide, and elimination of N,N-dimethylhydroxylamine from the resultant N-oxide.

Attempts to prepare 3-phenyl-1,4-benzoxathiane by acid-catalysed ring-closure of 2-(2-hydroxyphenylthio)-2-phenylethanol gave instead 2-phenyl-1,4- benzoxathiane, via a rearrangement probably involving an episulfonium ion. The first synthesis of 3-aryl-1,4-benzoxathianes was obtained by N-bromosuccinimide-promoted oxidative rearrangement of 1,3-oxathiolanes derived from cyclohexanone. The application of this route to the synthesis of 3-(3-hydroxy-4-methoxyphenyl)-1,4-benzoxathiane, a compound ca. 2000 times as sweet as sucrose, is reported.

A procedure is reported for the chemo- and stereo-selective sulfur removal from 5,6-dihydro-1,4-dithiins which completes the pathway to synthesize cis configurated olefins from carbonyl compounds. A four step synthesis of (Z)-9-tricosene (muscalure) with the dithiin moiety serving as the penultimate olefin precursor is also reported as an example of the proposed synthetic strategy.

A ready asymmetric synthesis of 3′-oxa-4′-thionucleosides has been accomplished in three main steps from benzoyloxyethanal. The synthesis is characterized by high overall yield and appreciable enantiomeric excesses. It represents a general synthetic scheme to prepare a wide range of heterosubstituted sulfur-containing nucleoside analogues.

2-[[O-(p-Methoxybenzyl)-oxy]methyl]-5,6-dihydro-1,4-dithiin 1 is a versatile three carbon homologation reagent which has been conveniently used in the synthesis of enantiomerically pure modified nucleosides.

α-D-Glycosyl iodides are stereoselectively obtained by iodine replacement of the free anomeric hydroxyl group of fully protected sugars treated with a polymer bound triarylphosphane-iodine complex and imidazole. High yields and mild conditions, compatible with all the common protecting groups used in carbohydrate chemistry, characterize the conversion.

TiCl4-Mediated Baylis–Hillman and aldol reactions were developed without the direct use of a Lewis base. These processes involve the conjugate addition of TiCl4 to α,β-unsaturated substrates followed by carbonyl coupling. Baylis–Hillman olefins were obtained when α,β-unsaturated ketones were employed as the substrates, whereas β-halogenated aldol products were generated with an α,β-unsaturated N-acyl benzoxalinone as the Michael-type acceptor.

A highly stereoselective method for the synthesis of (E)-β-halogeno Baylis–Hillman adducts has been developed. The new method involves a tandem α-hydroxyalkylation/β-chlorination of α,β-acetylenic ketones by using TiCl4 as the chlorine source for α,β-conjugate addition, and concurrently as the Lewis acid promoter for the carbonyl addition. The new system tolerates a broad scope of reactants in which aliphatic and aromatic α-acetylenic ketones can be subjected to the conjugate addition. Both aliphatic and aromatic aldehydes can also be employed as electrophilic acceptors. Good yields (61–88%) and high E/Z stereoselectivity have been obtained for the nine examples which were examined, only in one case was E/Z selectivity of 17/1 observed and the two individual isomers are separable via flash column chromatography.

The uncatalyzed reaction of C3-substituted cyclopropanes 1b–d with benzeneselenenyl chloride 3 leads to 1-ethyl 4-methyl 2-(phenylseleno)butanedioates 5b–d while the unsubstituted 1a gives the 3-phenylseleno derivative 6a. Formation of 5b–d occurs regio- and stereoselectively via electrophilic ring-opening of 1 while 6a results from the selenenylation of the alkene 2a formed via isomerization of 1a. The presence of TiCl4 influences the stereochemistry of the reaction with chloride 3 while it is essential for reaction of the less reactive PhSeCN 4. With this electrophile the reactions lead to α,α-dimethoxycarbonitriles 13a–d while only 1a and 1b give also the expected cyanoselenenyl derivatives 12a and 12b. Moreover, from 1b compound syn- 5b is obtained, and 1a gives, via the alkene 2a, esters 14a and 6a. A mechanistic interpretation suggests the intermediacy of well-stabilized dipolar species 9 which should be formed by coordination of the Lewis acid to the carbonyl oxygen of 1 and subsequent ring opening.

The asymmetric α-hydroxylation of N,N-diprotected homo-β-amino acid methyl esters is reported. The starting compounds are readily available, being prepared from simple α-amino acids by a procedure that we have already reported. α-Hydroxylation proceeded smoothly at −78 °C with high yields and good diastereomeric ratios. In comparison with other asymmetric α-hydroxylation procedures, (a) this method does not need the use of costly chiral reagents and/or chiral auxiliaries and (b) it represents the first example of a procedure affording β-amino-α-hydroxy acids with full, orthogonal protection. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

In part because of their straightforward and modular syntheses from readily available enantiopure starting materials, and their capacity to bind a wide variety of transition metals, chiral, chelating nitrogen-donor ligands have played a prominent role in asymmetric catalysis. A large number of highly enantioselective transformations rely upon these ligands whose reported classes are built around amine, imine, pyrrole, pyrrolidine, oxazoline and oxazolidine donor groups, among others. In this Perspective, we examine a selection of transformative developments in asymmetric catalysis by metal complexes of bi- and polydentate members of this ligand family. We describe approaches to ligand design and synthesis, structure and bonding in coordination complexes, and limitations and future challenges.