Thermal and photochemical reactions of a stable thiobenzaldehyde, 2,4,6-tri-t-butylthiobenzaldehyde

Thermal and photochemical reactions of the title compound gave benzothiolane $\text{2}$ in high yield; the reaction with free radicals also afforded $\text{2}$ along with some other products.     

Pd-catalyzed amidation of aryl(Het) halides with tert-butyl carbamate

Pd-catalyzed cross-coupling reaction of tert-butyl carbamate with various aryl(Het) halides with Cs₂CO₃ as base in 1,4-dioxane as solvent was investigated, which resulted in the formation of the desired compounds in moderate to excellent yields.     

A tert-butyl/cyano substituted (1,2,3,5-dithiadiazolyl)benzene and η π complexes with CpCr(CO)2

A rational synthesis for 5-tert-butyl-3-cyano-1-(1,2,3,5-dithiadiazolyl)benzene, which was first observed from thermal cleavage of the bis-dithiadiazolyl, has been developed. Voltammetry and electron paramagnetic resonance (EPR) spectra for this radical are reported and its X-ray structure is described. Despite the bulky ^tBu substituent, the cyano supramolecular synthon is still able to maintain links to a single neighbouring sulfur atom of the S₂ unit, as previously observed in cyano-substituted dithiadiazolyls. In the η² complex with CpCr(CO)₂, no such interactions are observed; the nitrile group forms a centrosymmetric dimer through weak contacts with the para H atom on the aryl ring of the partner molecule. This behaviour is contrasted to similar complexes of less bulky dithiadiazolyls, where intermolecular interactions are retained in the crystalline lattice.     

Asymmetric addition reactions of Grignard reagents to chiral 2-trifluoromethyl tert-butyl (Ellman) sulfinimine-ethanol adducts

The addition of Grignard reagents to chiral trifluoromethyl tert-butyl sulfinimine-ethanol adducts affords protected trifluoromethylamines in high yields with good to excellent diastereoselectivities. The stereochemical outcome of the addition is opposite to that expected via a chelation controlled transition state.     

Convenient synthesis of porphine from β-tetra(tert-butyl)porphyrin

β-Tetra(tert-butyl)porphyrin was prepared from 2-dimethylaminomethyl-4-tert-butylpyrrole and converted into porphine, the mother compound of porphyrins, in 64% yield. The dealkylation smoothly proceeded in aqueous sulfuric acid over 15 min at 190 °C under nitrogen.     

Synthesis and characterization of well-defined poly(tert-butyl acrylate) star polymers

Star polymers with different numbers and lengths of poly(tert-butyl acrylate) (PTBA) arms were obtained via atom transfer radical polymerization. Aliphatic alcohols with different number of hydroxyl groups varying from 3 to 6 and calix[4]arenes based on pyrogallol with 12 and 16 phenol groups were transformed to bromoester derivatives to prepare multifunctional ATRP initiators used as the cores of the stars. The star polymers were characterized by GPC with refractive index, multiangle laser light scattering and viscosimetric detectors. The molar masses of the stars reached 70,000 g/mol and the molar mass dispersities did not exceed 1.2. To elucidate the compact structure of the stars, their true molar masses were determined by GPC with triple detection (RI-MALLS-Visco) and compared with the apparent molar masses obtained from the calibration with linear poly(tert-butyl acrylate) standards. The intrinsic viscosities of the PTBA stars of the same molar mass decreased with the number of star arms but were always lower than the intrinsic viscosities of the analogue linear PTBA polymers. The values of the branching ratio g′ decreased with increasing number of arms indicating more compact structure of stars. The branching ratio g′ was correlated to the empirical predictions.     

Solution behavior of 4-arm poly(tert-butyl acrylate) star polymers

This paper reports the synthesis of 4-arm poly(tert-butyl acrylate) stars of different molar masses up to 10⁶ g/mol by the “core-first” method using ATRP. All obtained stars have a monomodal and narrow molar-mass distribution (<1.2).The dilute-solution properties of these star polymers were investigated in good solvents (tetrahydrofuran and acetone). Gel permeation chromatography and dynamic and static light scattering were used to measure the hydrodynamic properties including intrinsic viscosity [η], radius of gyration R_g, hydrodynamic radius R_h, second virial coefficient A₂ and diffusion coefficient D₀. These data were used to establish relationships between these parameters and the molar mass of 4-arm poly(tert-butyl acrylate) stars. The branching parameters g and g′ and the shape factor ρ were calculated for all obtained star polymers.     

Sulfide oxygenation by tert-butyl hydroperoxide with mononuclear (Me3TACN)Mn catalysts

Mononuclear (Me₃TACN)MnX₃ compounds, where X is Cl⁻, Br⁻, or N₃⁻, and Me₃TACN is 1,4,7-N,N′,N″-trimethyl-1,4,7-triazacyclononane, have been tested for catalyzing both sulfide oxygenation and styrene epoxidation by tert-butyl hydroperoxide (TBHP) and display turnover frequencies (TOF) up to 200 h⁻¹ at room temperature. Sulfoxides or sulfones may be produced selectively by varying reaction conditions. Product distribution from the oxygenation reactions of ethyl phenyl sulfide, 2-chloroethyl phenyl sulfide, and styrene is consistent with a mechanism involving an early single-electron transfer (SET) step.     

Liquid–liquid equilibria for binary systems of tert-amyl ethyl ether (TAEE), isopropyl tert-butyl ether (IPTBE) and di-sec-butyl ether (DSBE) with water and for ternary systems with methanol or ethanol

The liquid–liquid equilibria for binary systems of tert-amyl ethyl ether (TAEE) + water, isopropyl tert-butyl ether (IPTBE) + water and di-sec-butyl ether (DSBE) + water are analytically determined in the temperature range 278.65–358 K. Additionally, tie-lines for six ternary systems of TAEE, IPTBE and DSBE with methanol and water or with ethanol and water are also measured at 298.15 K. All the measured binary and ternary data were correlated with the NRTL and UNIQUAC model. The reliability of the experimental tie-line data for ternary systems was ascertained by using the Othmer–Tobias correlation.     

Phosphine-catalyzed [3+3] annulation reaction of modified tert-butyl allylic carbonates and substituted alkylidenemalononitriles

A phosphine-catalyzed [3+3] annulation reaction of modified tert-butyl allylic carbonates with various alkylidenemalononitriles to form cyclohexenes was developed. The use of protic solvent is crucial in this reaction. When non-polar solvent, toluene or xylene, was used, only non-cyclized product was obtained.     

TBHP/TBAI-mediated oxidation of thiophenols for the synthesis of tert-butyl arylsulfinates

A novel and efficient TBHP/TBAI-mediated oxidation of thiophenols is described. The reactions proceeded smoothly to give tert-butyl arylsulfinates in up to 82% yield with good functional group compatibility under mild conditions.     

Glycosylative transcarbamylation: efficient transformation of tert-butyl carbamates to novel glycoconjugates

Reaction of a variety of tert-butyl carbamates under glycosylation conditions gives rise to anomeric 2-deoxy-2-amino sugar carbamates in a good to excellent yields. The reaction exhibits good tolerance to several common protecting groups, and has been used to generate unnatural glycopeptide building blocks.     

Phosphonate-free phosphorylation of alcohols using bis-(tert-butyl) phosphoramidite with imidazole·hydrochloride and imidazole as the activator

A variety of commercially available alcohols were converted to their bis-(tert-butyl) protected mono-phosphate pro-drugs. The improved procedure uses the unique combination of imidazole·hydrochloride and imidazole as the activator to suppress the formation of undesired phosphonate by-product frequently encountered with the bis-(tert-butyl) phosphoramidite reagents. The new activation procedure eliminates the need to use excess reagents.     

Coordination chemistry of 2,4,6-tri(pyridyl)-1,3,5-triazine ligands

This review covers the rich coordination chemistry of 2,4,6-tri(pyridyl)-1,3,5-triazine ligands. These polypyridyl derivatives have been coupled to transition metals and lanthanides, and the complexes obtained have been used in various fields such as luminescent materials, for the preparation of coordination polymers and networks as well as for the synthesis of discrete metalla-assemblies. The synthetic and structural aspects of the different isomers of 2,4,6-tri(pyridyl)-1,3,5-triazine are presented, and a survey of their coordination chemistry is given.     

Reaction between tert-butyl isocyanide, dialkyl acetylenedicarboxylates, and aromatic carboxylic acids: an efficient method for the synthesis of dialkyl (E)-2-{[benzoyl(tert-butyl)amino]carbonyl}-2-butenedioate derivatives

Protonation of the reactive intermediates produced in the reaction between tert-butyl isocyanide and dialkyl acetylenedicarboxylates by aromatic carboxylic acids leads to vinylnitrilium cations, which undergo nucleophilic reaction with conjugate bases of the carboxylic acids to produce dialkyl (E)-2-[(benzoyloxy)(tert-butylimino)methyl]-2-butenedioates and this intermediate rearranges to the dialkyl (E)-2-{[benzoyl(tert-butyl)amino]carbonyl}-2-butenedioate derivatives.     

Gold-catalyzed cyclization of tert-butyl allenoate: general synthesis of 2,4-functionalized butenolides

AuCl₃ efficiently catalyzes cyclization of tert-butyl allenoates into γ-butenolides. Advantage of directly using allenic ester precursor instead of corresponding acid is demonstrated in the synthesis of a variety of 2,4-disubstituted butenolides. A low catalyst loading and mild reaction condition makes this process an attractive alternative over conventional methods using strong Lewis acids.     

Iridium catalysed alkylation of tert-butyl cyanoacetate with alcohols under solvent free conditions

Ir-catalysed alkylation of tert-butyl cyanoacetate with a range of substituted benzyl and heteroaryl alcohols under solvent free conditions afforded the corresponding monoalkylated products in moderate to high yields.     

Reversal of diastereoselection in the addition of Grignard reagents to chiral 2-pyridyl tert-butyl (Ellman) sulfinimines

Addition of Grignard reagents to chiral tert-butyl sulfinimines derived from pyridine 2-carboxaldehyde affords protected 2-pyridyl amines in high yields and diastereoselectivities. The sense of chiral induction is opposite to that predicted via a chelation-controlled transition state.