PhI(OAc)2/KI mediated 1,2-acetoxysulfenylation of alkenes: facile synthesis of β-acetoxysulfides

A convenient method for 1,2-acetoxysulfenylation of alkenes using disulfide promoted by (diacetoxyiodo)benzene (PhI(OAc)₂, DIB)/KI was developed. The reaction is highly regioselective for styrene derivatives while aliphatic alkenes lead to a mixture of two regioisomers.     

Synthesis of high-molecular-weight poly(ε-caprolactone) catalyzed by highly active bis(amidinate) tin(II) complexes

A series of bis(amidinate) tin(II) complexes is synthesized and shown to rapidly polymerize ε-caprolactone (ε-CL) in the presence and absence of benzyl alcohol giving high-molecular-weight poly(ε-CL) (M(n) up to 160,600 Da). Ligands having electron donating groups were found to accelerate the polymerization by making the complex more nucleophilic.     

Difluorophenylsulfanylmethyl radical and difluoromethylene diradical synthons: gem-difluoromethylene building block

Bromodifluorophenylsulfanylmethane has been demonstrated to be a highly versatile gem-difluoromethylene (CF2) building block via the reaction of difluorophenylsulfanylmethyl radical with olefins. gem-Difluoroalkenes and products containing a midchain CF2 group and with manipulatable functionality can be readily synthesized. The first example of a gem-difluoromethylene radical synthon is also reported.     

On interpolation of noncommutative symmetric Hardy spaces

We proved the noncommutative analogue of Calderón’s result for fully symmetric spaces \(E_1\) and \(E_2\) on (0, 1) and for a finite von Neumann algebra \({{\mathcal {M}}}\). We also proved the noncommutative symmetric Hardy space’s analogue of Calderón’s result for fully symmetric spaces and for finite subdiagonal subalgebras.     

Chemical Indices and Kinetic Evaluation of β-Sitosteryl Oleate Oxidation in a Model System of Bulk Oil

Concerns have been raised about the safety and tolerability of phytosterol esters due to their vulnerability to oxidation. Herein, oxidation of the unsaturated fatty acid-phytosterol ester, namely β-sitosteryl oleate, was observed in comparison to native β-sitosterol after accelerated storage at 65 °C for 35 days in a bulk oil model system. Depending on the sterol structure, various chemical indices of lipid oxidation, including hydroperoxide value (HPV), thiobarbituric acid reactive substances (TBARS), p-anisidine value (AnV), and 7-keto derivatives, changed at varying rates in both samples. Such indicators for β-sitosteryl oleate appeared to be obtained at higher concentrations than those for β-sitosterol. The first order kinetic was used to describe the losses of β-sitosteryl oleate and β-sitosterol in bulk oil. It was discovered that the β-sitosteryl oleate (k = 0.0202 day⁻¹) underwent oxidative alteration more rapidly than β-sitosterol (k = 0.0099 day⁻¹). Results indicated that physical structure was the principal factor in the determination of storage stability of phytosterol and its ester. Research on antioxidants and storage techniques can be expanded in order to reduce the oxidative loss of phytosterol esters during storage and improve the safety and tolerability of phytosterol esters.     

Generation of dienone and trienone dianion derivatives : Double deprotonation as a route to lumo-filled π-systems

Conjugated unsaturated carbonyl compounds and their analogues 1 are a^1,3,5...-reagents. An umpolung of this intrinsic reactivity can be achieved by generation of the dianions 2, LUMO filled π-systems, from hydrogenated precursors, see schemes 1 and 2. The preparation of the allylated ketones 3a–d, of the acid derivatives 3e–h, 9, 10, 12 as well as of the dienones 11 is described. Their double deprotonation (→14, 18, 26, 30, 33, 36, and 40) is carried out by sequential treatment with potassium hydride and s-butyllithium/tetramethylethylene diamine (TMEDA) in THF. The decisive role of potassium in the second deprotonation step is demonstrated (Table 1 and eqn (6)). The brightly colored suspensions or solutions of these Li/K-dianions were quenched with the electrophile benzophenone. The products (15, 20, 27, 31, 34, 37, 41) result exclusively from ω-reactivity (d⁵- and d⁷reactivity) of the ambident dianionic nucleophiles (cf formulae 2, n = 2,3).     

Reductions between types of numberings

This paper considers reductions between types of numberings; these reductions preserve the Rogers Semilattice of the numberings reduced and also preserve the number of minimal and positive degrees in their semilattice. It is shown how to use these reductions to simplify some constructions of specific semilattices. Furthermore, it is shown that for the basic types of numberings, one can reduce the left-r.e. numberings to the r.e. numberings and the k-r.e. numberings to the $(k+1)$-r.e. numberings; all further reductions are obtained by concatenating these reductions.     

Anion of 1-[(2-methoxyethoxy)methoxy]-2-phenylsulfonylcyclopropane as a new d3-reagent: preparation of β-substituted α,β-unsaturated aldehydes

Preparation of β-alkylsubstituted α,β-unsaturated aldehydes using a new d³-reagent is described.     

Facile oxidative hydrolysis of acetals to esters using hypervalent iodine(III)/LiBr combination in water

The combination of (diacetoxy)iodobenzene (PhI(OAc)₂, DIB) and lithium bromide (LiBr) efficiently oxidized cyclic and acyclic acetals to the corresponding hydroxyalkyl carboxylic esters and simple esters in good to excellent yields. The merits of this reaction are that it employs commercially available and non-explosive hypervalent iodine(III) reagent, water as the solvent, a short reaction time, and mild reaction conditions.