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A protocol for effecting a rapid Saegusa-type oxidation of enol acetates is reported. This new method relies on the in situ elimination of an α-bromo intermediate to generate α,β-unsaturated ketones using copper(II) bromide. The methodology developed was applied to a range of substrates including a cyclohexanone, which could be directly converted to the corresponding phenol derivative. A catalytic system in which a non-masked ketone was successfully oxidised using substoichiometric CuBr2 was also developed as a proof of principle.

Chiral diols and biphenols catalyze the multicomponent condensation reaction of phenols, aldehydes, and alkenyl or aryl boronates. The condensation products are formed in good yields and enantioselectivities. The reaction proceeds via an initial Friedel–Crafts alkylation of the aldehyde and phenol to yield an ortho-quinone methide that undergoes an enantioselective boronate addition. A cyclization pathway was discovered while exploring the scope of the reaction that provides access to chiral 2,4-diaryl chroman products, the core of which is a structural motif found in natural products.

A diverse range of alkene containing oxime esters is transformed with multiple nucleophiles, including tetraaryl borates, (het)aryl, alkenyl, and alkynyl boronates as well as alcohols, with or without concomitant carbonylation.

The reaction tolerates electronically and sterically diverse N-aryl arylsulfonamides, but is not applicable to alkyl substituted substrates.

Here we provide a guide for adapting the tools developed for protein X-ray crystallography to study the structures and supramolecular assembly of peptides. Peptide crystallography involves selecting a suitable peptide, crystallizing the peptide, collecting X-ray diffraction data, processing the diffraction data, determining the crystallographic phases and generating an electron density map, building and refining models, and depositing the crystallographic structure in the Protein Data Bank (PDB). Advances in technology make this process easy for a newcomer to adopt. This paper describes techniques for determining the X-ray crystallographic structures of peptides: incorporation of amino acids containing heavy atoms for crystallographic phase determination, commercially available kits to crystallize peptides, modern techniques for X-ray crystallographic data collection, and free user-friendly software for data processing and producing a crystallographic structure.

(Cyclopentadienyl)(cyclooctadiene) ruthenium(II) chloride [CpRuCl(cod)] catalyzes the reaction between nitrile oxides and electronically deficient 1-choro-, 1-bromo-, and 1-iodoalkynes leading to 4-haloisoxazoles. Organic azides are also suitable 1,3-dipoles, resulting in 5-halo-1,2,3-triazoles. These air-tolerant reactions can be performed at room temperature with 1.25 equivalents of the respective 1,3-dipole relative to the alkyne component. Reactive 1-haloalkynes include propiolic amides, esters, ketones, and phosphonates. Post-functionalization of the halogenated azole products can be accomplished by using palladium-catalyzed cross-coupling reactions and by manipulation of reactive amide groups. The lack of catalysis observed with [Cp*RuCl(cod)] (Cp* = pentamethylcyclopentadienyl) is attributed to steric demands of the Cp* (η(5)-C5Me5) ligand in comparison to the parent Cp (η(5)-C5H5). This hypothesis is supported by the poor reactivity of [(η(5)-C5Me4CF3)RuCl(cod)], which serves as a an isosteric mimic of Cp* and as an isoelectronic analogue of Cp.

A safe and facile method for the formation of 3-trifluoromethyl-5-amino-1,2,4-oxadiazoles, via a reversed addition of hydroxylamine to cyanamides, is reported. This two-pot procedure is suitable to scale-up and avoids the hazards associated with trifluoromethyl amidoxime synthesis.

A sequential Diels–Alder reaction/silicon-directed [4 + 2]-annulation was developed to assemble hydroisochromene-type ring systems from menadione 2. In the first step, a Diels–Alder of the 1-silyl-substituted butadiene 1 with 2 furnished an intermediate cyclic allylsilane. Subsequently, TMSOTf promoted a [4 + 2]-annulation through trapping of an oxonium, generated by condensation between an aldehyde and the TBS protected alcohol resulted in the formation of a cis-fused hydroisochromene 13.

The mechanistic pathway involves radical-based C-N bond formation and does not involve migratory insertion of the alkene into the N-Cu bond of an imino-Cu(III) intermediate.

A rhodium(II) catalyzed nitrene–alkyne cycloaddition of stereochemically well-defined homopropargylic ethers is followed by arene cyclopropanation to afford unique tetracyclic norcaradiene products bearing a cyclic sulfamate. Products from the arene cyclopropanation (Buchner reaction) can be converted to fused cycloheptatrienes via a ring enlarging electrocyclization after nucleophilic ring opening of the cyclic sulfamate ester.

The title reaction is operationally simple and has wide scopes with respect to both the oxime esters and the alkenes.

Reductive coupling of propargylsilanes with alkenols is found to result in efficient and stereoselective formation of functionalized allylsilanes such as (III), (X), and (XIII).

Three-component aminocrotylation reaction of the novel silanes (I) and (XIII) leads to homoallylic carbamates bearing an unsaturated ester or allylic carbonate in good syn-selectivity.

Three different types of isoxazoline-containing polycyclic heterocycles are prepared from the corresponding oxime precursors (syntheses described).

Lactones and oxazolidones are effectively α-arylated using the diaryliodonium hexafluorophosphates and Cu(I)--bisoxazoline catalyst.

The utility of a sequence consisting of organosilane-based carbonylation followed by Rh(II)-catalyzed asymmetric carbenoid transformation is demonstrated for the synthesis of different types of polycyclic heterocyclic frameworks such as (XI)-(XIV),.

The nucleophile adds exclusively to the α-face of the oxonium ion intermediate and high diastereoselectivity is observed for all products.

Catalytic enantioselective strategies have become synthetically useful to access P-stereogenic phosphines. To date, enantioselective desymmetrisations and dynamic kinetic resolutions dominate the field. Desymmetrisation strategies do not necessarily require the formation of a P-carbon or P-heteroatom bond. This approach has been validated with variable levels of success using organocatalysed asymmetric deprotonation (chiral diamine) or methylation (phase transfer catalysis), enzyme-mediated esterification, rhodium catalysed [2+2+2] cycloadditions and more recently molybdenum-based ring closing metathesis. The dynamic kinetic resolution of racemic P-templates relying on a P–C bond-forming event has been the object of extensive investigations, which have culminated with the arylation and alkylation (benzylation) of equilibrating diastereomeric palladium, platinum or ruthenium phosphido complexes. Although all these routes allow access to a myriad of highly interesting P-stereogenic compounds, the level of enantiocontrol is substrate- and reactant-dependent. Pleasingly, ee’s up to 98% were obtained on selected systems.

The purpose of this critical review is twofold: first, to review organic “small molecule” crystalline materials in terms of structure and function; and second, to consider if and how such materials might eventually enter the realm of device applicability. This area, one of the most interdisciplinary fields of research in contemporary materials science, embraces chemistry, physics, engineering, biology, theory and computation. The review therefore attempts to treat a relatively large number of examples including fundamental physical and electronic structure, single component and charge transfer complexes, physical properties of single crystalline materials, thin film and single crystal electronic and photonic devices, functional materials, and bio-inspired structures. The point of view is that of an experimental physicist, and in this context, challenges and possible routes to further advances in the development and utilization of organic small molecule materials are discussed for both fundamental and applied purposes (153 references).

Substrates (I), (VII), and (XIII) undergo ring-opening with various nucleophiles to produce 1H-indazolone products.

Chiral homoallylic ethers, bearing a α,β-unsaturated ester or silyl ether moiety, are prepared with moderate to high syn-selectivity via the crotylation reaction of chiral silanes, aldehydes and trimethylalkoxysilanes.

(R)-O-acetyl mandelic acid has been utilized for the development of a procedure for resolution and absolute stereochemical assignment of C1-oxygenated E-crotylsilanes 1a-c. The procedure is enhanced further by an efficient boron trifluoride etherate catalyzed allylic transposition which generates E-vinylsilanes. Subsequent resolution and hydrolysis produced the vinylsilanes 6a, b and d in optically active form. The published method of Trost and cowoarkers has allowed for the assignment of absolute stereochemistry.

A novel five-step sequence for the synthesis of genistein (VIb) from ketone (Ia) involves formation of the enamino ketone (III) followed by ring closure and Suzuki coupling.

The Ireland ester Claisen rearrangement of chiral (R)- and (S)-C3-(acyloxy)-(E)-vinylsilanes gives access to a wide range of α-chiral-β-silyl-(E)-hexenoic acids with useful levels of diastereoselectivity for both the 2,3-syn and 2,3-anti diastereomers as illustrated in eqs 1 and 2. The vicinal diastereoselectivities for simple propionate esters rac-1b, (S)-1e, and (R)-1g can be varied from 1:12 to 16:1 (syn:anti) depending on reaction conditions. The employment of appropriately protected glycolate esters yields Claisen products with diastereoselectivities ranging from 23:1 (syn:anti), resulting from chelation control of enolate geometry, to 1:3.6 (syn:anti) via the use of a nonchelating, silicon-protecting group. The reaction of α-azido acetate (R)-1i is the first example of a Claisen rearrangement involving an α-azido ester and results in a new approach toward the asymmetric synthesis of α-amino acids

Syn-α,β-dialkoxy-acyldimethylphenylsilanes of structural type 1 , bearing benzyl, benzyloxymethyl (BOM) ether protecting groups can be efficiently and selectively desilated to produce the corresponding aldehydes 2 by catalytic hydrogenolysis over 10% palladium on carbon in ethanol or ethyl acetate.

The fracture toughness of chemically vapor-deposited diamond is estimated by a Vickers indentation method. Freestanding diamond films of 400-μm thickness are produced with plasma-enhanced chemical vapor deposition and highly polished for indentation testing. Indentation testing was performed with a microhardness tester using a load range of 5 to 8 N. The average fracture toughness is estimated as 5.3 ± 1.3 MPA · m1/2.

Methyl α-methyl-β-(dimethylphenylsilyl)-(E)-hex-4-enoates (2S,3R)-1a undergo BF 3 -OEt 2 -promoted additions with (S)-2-(benzyloxy)propanal (2) producing nearly enantiomerically pure cis-2,5-substituted tetrahydrofurans 3 whereas the reactions run under chelation controlled conditions employing SnCl 4 resulted in the formation of the complementary trans-2,5-disubstituted tetrahydrofuran. Additions to the enantiomeric silane (2R,3S)-1b utilizing BF 3 -OEt 2 or SnCl 4 afforded the cis-2,5-disubstituted furan stereochemistry in both cases

Complete details of a study leading to the asymmetric synthesis of the AB-ring system of (+)-sesbanimide A (1), a potent cytotoxic agent belonging to the class of sesbania alkaloids, are described. Key features of the synthesis include (a) the stereoselective introduction of the C8 and C9 hydroxyl groups through the use of a diastereoselective catalytic osmylation of enantiomerically enriched α-alkoxy allylsilanes and (b) a chelation-controlled nucleophilic addition of a vinyl Grignard reagent to a syn α-alkoxy β-(silyloxy) aldehyde for the introduction of the C7 stereocenter required for assembly of the B-ring

Functionalized (E)-crotylsilanes 1 bearing a bis-homoallylic hydroxyl group undergo diastereoselective cyclopropanation and epoxidation reactions to produce substituted tetrahydrofurans 3 and 5 respectively after an acid catalyzed heterocyclization.

The condensation between chiral (E)-crotylsilanes (1) and in situ-gene- rated achiral N-acylimines produces homoallylic N-acylamines (3) or te- trasubstituted N-acylpyrrolidines (4) with high levels of diastereose- lection

The potential energy curves of the low-lying electronic states of two diatomic (+2) ions AlF2+ and SiF2+ have been calculated by using a multireference CI method with an extended Gaussian basis set. The X1Σ+ state of AlF2+ is predicted to be thermodynamically stable by 1.89 eV, with a barrier to dissociation of 3.29 eV. SiF2+ has two thermodynamically stable electronic states, X2Σ+ bound by 1.89 eV and 12Π bound by 0.68 eV. These dications can therefore be added to a growing list of such dications which are thermodynamically stable in their ground electronic states. The nature of the bond in these species is described and the spectroscopic parameters are reported. Some possible ways of observing the ions are discussed.