Reactivity of Various α-Halo Ketones in One-Pot Synthesis of γ-Iminolactones

The highly reactive 1:1 intermediate generated in the reaction of tert-butyl isocyanide and dialkyl acetylenedicarboxylate is trapped by α-halo ketones to produce halogenated iminolactones as the sole product in good yields.     

Convenient Preparation of Cycloalkenyl Boronic Acid Pinacol Esters

A practical method for the preparation of cycloalkenyl boronic acid pinacol esters is described. These important synthetic intermediates are typically made using more expensive methods like transition metal-catalyzed borylation of alkenyl halides or triflates. In this work, they are obtained from the simple corresponding cycloalkanones, which are subjected to Shapiro reaction conditions followed by trapping with a borate ester. The requisite products are obtained in very good to excellent yields, and the reactions can be scaled up to multigram amounts. By providing a simple alternative to common methods that make use of expensive transition-metal catalysts and formation of sensitive intermediates, this convenient method will be useful for the synthesis of ring-containing partners for Suzuki–Miyaura cross-coupling and other reactions employing boronic esters as substrates.     

Development of a manual method for the determination of mineral oil in foods and paperboard

So far the majority of the measurements of mineral oil saturated hydrocarbons (MOSH) and mineral oil aromatic hydrocarbons (MOAH) were obtained from on-line high performance liquid chromatography–gas chromatography–flame ionization detection (on-line HPLC–GC–FID). Since this technique is not available in many laboratories, an alternative method with more easily available tools has been developed. Preseparation on a small conventional liquid chromatographic column was optimized to achieve robust separation between the MOSH and the MOAH, but also to keep out the wax esters from the MOAH fraction. This was achieved by mixing a small portion of silica gel with silver nitrate into highly activated silica gel and by adding toluene into the eluent for the MOAH. Toluene was also added to the MOSH fraction to facilitate reconcentration and to serve as a keeper preventing loss of volatiles during solvent evaporation. A 50 μl volume was injected on-column into GC–FID to achieve a detection limit for MOSH and MOAH below 1 mg/kg in most foods.     

Iron(III) Chloride–Promoted Direct Conversion of Aryl/Alkyl Cyanides to Esters

Aryl/alkyl cyanides were quickly converted into the corresponding esters in the presence of iron(III) chloride in refluxing alcohols with very good yields.     

Conjugate Addition of a Silyl Ketene Acetal to α,β‐Unsaturated Lactones

Abstract

Conjugate addition of a silyl ketene acetal [Me₂C?C (OMe)OSiMe₃] to α,β‐unsaturated lactones (namely, 5,6‐dihydro‐2H‐pyran‐2‐one, 2(5H)‐furanone as Michael acceptor) occurs efficiently at room temperature in the presence of a nucleophilic catalyst, tetra‐n‐butyl ammonium bibenzoate (TBABB), in THF as well as Lewis acid catalysts such as Yb(OTf)₃ and I₂ in CH₂Cl₂, giving the corresponding 1,4‐adducts in excellent yields.     

Influence of Carboxylic Acids on the Synthesis of Chlorohydrin Esters from 1,3‐Butanediol

The influence of diverse carboxylic acid on the preparation of chlorohydrin esters using a one‐pot esterification–chlorination reaction, in which one of the reagents (chlorotrimethylsilane) acts as solvent, is described. Whereas the acid with low pKa provided higher amounts of the 2‐chloro regioisomer, the ones with higher pKa rendered the 1‐chloro regioisomer in 80% yield. These results are in accordance with the mechanism proposed in a previous article.     

Chemoselective Removal of Acyloxy in 1-(Benzotriazole-1-yl)alkyl Esters and Its Application in the Preparation of β-(Benzotriazole-1-yl)alcohols

Mediated by samarium diiodide, 1-(benzotriazole-1-yl)alkyl esters 1 underwent cross-coupling with aldehydes or ketones to afford β-(benzotriazole-1-yl)alcohols 2 exclusively with the selective removal of acyloxy over benzotriazolyl.     

Highly Enantioselective Hydrogenation of β‐Alkyl and β‐(ω‐Chloroalkyl) Substituted β‐Keto Esters

Highly enantioselective hydrogenation of β‐alkyl and β‐(ω‐chloroalkyl) substituted β‐keto esters was achieved with Ru catalysts based on chiral diphosphines in EtOH at 50°C under 50‐bar initial hydrogen pressure, affording the corresponding β‐hydroxy esters in >98% ee.     

A Facile Synthesis of 2-Benzoyl-6-Hydroxy-3-Methyl-5-(2-Substituted-2,3-Dihydro-1H-1,5-Benzodiazepin-4-YL) Benzo[b]Furans

The synthesis and characterisation of some new 1,5-benzodiazepines prepared from 4,6-diacetylresorcinol is reported.     

The Calculus of HLB Values of Polyoxyethylene Fatty Acid Esters from Quality Control Data

In this article, we obtained equations that permit us to calculate the hydrophilic-lipophilic balance (HLB) value of polyoxyethylene esters from quality control data of the raw materials (fatty acids and polyethylene glycol) and the finished product (surfactant). These data include the acid value of the fatty acid, the hydroxyl value of the polyethylene glycol, and the hydroxyl value of the surfactant. These calculations permit us, moreover, to know the mean molecular masses of fatty acids, of polyethylene glycol, of monoester and diester, and the proportion of polyoxyethylene monoester and polyoxyethylene diester.