Asymmetric allylation of aldehydes with allyltrichlorosilane promoted by chiral sulfoxides

Allylation of aldehydes with allyltrichlorosilane in the presence of sulfoxides is reported. The use of excess of (R)-methyl-p-tolylsulfoxide resulted in the formation of the corresponding homoallylic alcohols in good yields and moderate enantiomeric excesses.     

(S)-(+)-N-acetylphenylglycineboronic acid: a chiral derivatizing agent for Ee determination of 1,2-diols

A new chiral derivatizing agent for ee determination of 1,2-diols via (1)H NMR is described. (S)-(+)-N-acetylphenylglycineboronic acid (1) is synthesized in enantiomerically pure form; its reaction with chiral diols quantitatively yields cyclic boronic esters 5a-g. The latter show a remarkably high diastereodifferentiation of proton NMR signals useful for de determination. [reaction: see text]     

Some Multiply Derived Translation Planes with SL(2,5) as an Inherited Collineation Group in the Translation Complement

Finite translation planes having a collineation group isomorphic to SL(2,5) occur in many investigations on minimal normal non-solvable subgroups of linear translation complements. In this paper, we are looking for multiply derived translation planes of the desarguesian plane which have an inherited linear collineation group isomorphic to SL(2,5). The Hall plane and some of the planes discovered by Prohaska [10], see also [1], are translation planes of this kind of order q ²;, provided that q is odd and either q ²; 1 mod 5 or q is a power of 5. In this paper the case q ² -1 mod 5 is considered and some examples are constructed under the further hypothesis that either q 2 mod 3, or q 1 mod 3 and q 1 mod 4, or q -1 mod 4, 3 q and q 3,5 or 6 mod 7. One might expect that examples exist for each odd prime power q. But this is not always true according to Theorem 2.     

Electron and electrospray ionization mass spectrometry in the characterization of some 1-allyl-3-phenylaziridines

A series of cis- and trans-isomeric aziridines has been studied under electron impact (EI) and electrospray ionization (ESI) conditions. The fragmentation patterns of the examined compounds have been elucidated by means of sequential product ion fragmentation experiments (MS(n)) performed using an ion trap mass spectrometer. Particular attention has been paid to isomer characterization in these precursors of azetidinones, that in turn are precursors of new beta-lactam antibiotics.     

On the strong maximum principle

This paper presents a necessary and sufficient condition on the convex function in order that continuous solutions to

satisfy a Strong Maximum Principle on any open connected .

     

Solvent-free Mukaiyama and Mukaiyama-Michael vinylogous reactions of a dioxinone-derived silyl enol ether promoted by Lewis bases

The vinylogous aldol-type addition of a dienolsilyl ether, derived from 2,2,6-trimethyl-4H-1,3-dioxin-4-one, showed to occur with complete γ-selectivity by enolate activation promoted by neutral Lewis bases under solvent-free conditions. Moderate to high yields were obtained with aromatic, hetero-aromatic, and aliphatic aldehydes, as well as activated ketones. Under the same conditions and in the absence of catalyst, the first Mukaiyama-Michael addition of the masked acetoacetate ester to α,β-unsaturated aldehydes took place in satisfactory way.     

Orange Peel Biomass-derived Carbon Supported Cu Electrocatalysts Active in the CO2-Reduction to Formic Acid

We report a green, wet chemistry approach towards the production of C-supported Cu electrocatalysts active in the CO₂ reduction to formic acid. We use citrus peels as a C support precursor and as a source of reducing agents for the Cu cations. We show that orange peel is a suitable starting material compared to lemon peel for the one-pot hydrothermal synthesis of Cu nanostructures affording better Cu dispersion as well as productivity and selectivity towards formic acid. We rationalize this finding in terms of the beneficial chemical composition of the orange peel, which favors both the reduction of the Cu precursor as well as the carbon matrix. This work demonstrates new viable opportunities for the reuse of citrus waste on a rational basis.