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Hetero Diels-Alder (HDA) reactions between 2,3-dimethyl-1,3-butadiene and diethyl ester of aroyl phosphonates catalyzed by AlCl3 to afford (3,6-dihydro-2H-pyran-2-yl) phosphonate derivatives were investigated. Aroyl phosphonates with electron-withdrawing groups generally resulted in better isolated chemical yields. A stoichiometric amount of AlCl3 rather than a catalytic amount was necessary to activate the cycloaddition reaction. The amount of AlCl3 catalyst and its effect on LUMO of ethyl ester benzoyl phosphonate were also investigated by performing density functional theory (DFT) (B97D/6-31+G(d,p)) computations in dichloromethane. An increased loading of AlCl3 induced a considerable decrease in the LUMO energy of ethyl ester of benzoyl phosphonate. The computed Gibbs free activation energy is 17.03 kcal/mol in DCM at 0°C using the same computational level.

This article suggests the deployment of a unique mathematical tool for assessing the thermo-acoustic instability (TAI) in a Rijke tube and proposes an analytical design strategy for its feedback control. A widely accepted characteristic of TAI is its time-delayed dynamics, which originate from the regenerative acoustic coupling terms. Linear systems theory has also evolved on similar classes of problems especially in recent years. This document offers a bridge between the two veins of research. We first review the analytical model of the TAI phenomenon, which renders a set of delayed differential equations. Then, we apply a new mathematical tool called the cluster treatment of characteristic roots (CTCR) paradigm on this dynamics. CTCR provides non-conservative and exhaustive stability predictions for this class of systems. This capability is employed for both uncontrolled and feedback-controlled Rijke tube structures. The findings are unique from two angles: (i) stability declarations are made in the par...

Different aliphatic and aromatic acyl phosphonates were synthesized using Arbuzov reaction and subjected to Oxo-Diels-Alder (ODA) reaction with 2,3-dimethyl-1,3-butadiene at -78 °C. AlCl3 was found the best catalyst to obtain the desired ODA products from acyl phosphonates in only 30 minutes at low temperature, as compared to 100 °C - previously reported. The same reaction was repeated at room temperature but, instead of ODA, Wittig-type product was obtained. All the products were characterized by NMR spectroscopy and mass spectrometry. 1H,31P and 13C,31P couplings were observed in the NMR spectra.

In this study, the production of enantiopure benzoin from rac-benzoin acetate was achieved by lipase catalyzed kinetic resolution combined with deracemization using Rhizopus oryzae (CBS111718). The growth cells were pretreated with 20 kHz and 30 kHz ultrasound irradiation and mechanical homogenization. Approximately 100% conversion and 96% enantiomeric excess of the product (S-benzoin) were obtained by applying 20 kHz ultrasound irradiation at pH 6. The deracemization process involves new and important processes that allow for the transformation of a racemate into a single stereoisomeric product in 100% theoretical yields. Moreover, the application of ultrasound increases the conversion rate by reducing mass transfer limitation.

(±)-Mintlactone has been synthesized by applying a novel effective synthetic sequence. 4-Methylcyclohexanone was subjected to acetoxylation with Pb(OAc)4. Hydrolysis followed by reaction with 2-chloropropionyl chloride, then treatment with triethyl phosphite and, finally, Horner-Emmons-type intramolecular cyclization afforded (±)-Mintlactone.

The alkylation of l- and d-menthyl valerate with n-hexyl iodide and with (20S)-20-iodomethyl-4α-methyl-5α-pregnane gave modest levels of diastereoselection. The chirality of the ester group favoured slight degree of selectivity. The chiral centers had limited impact on diastereoselectivity

2-Substituted epichlorohydrins have been synthesized by starting with 1,2-dichloro acetone and various alkyl and aryl halides via dichlorohydrins followed by cyclization. The reactive 2-substituted epichlorohydrins were subjected to nucleophilic attacking of azide and cyanide ions to afford corresponding β-azido alcohols and α,β-unsaturated nitriles.

The asymmetric ene reactions of prochiral chloroaldehydes, chloral and 2,3-dichlorobutanal with 2-methylpropanal in the presence of BF 3 l-menthylethyl etherate gave optically active homoallylic alcohols in 16–22% ee. The dechlorination of the chloro alcohols lead to the unsaturated derivatives of alcohols.

The α-oxidation of cyclic derivatives of α-alkoxy-α, β-unsaturated ketones using manganese(III) acetate in the presence of various carboxylic acids provided a convenient synthesis of 5-acyloxy-2-alkoxy-2-cyclopentenones and 6-acyloxy-2-alkoxy-2-cyclohexenones.

Reaction of trichloronitromethane with secondary amine leads to the formation of corresponding carcinogeneous N-nitrosamines under mild conditions.

Short simple synthesis of alkenoic acid esters and their intramolecular cyclization products, 2H-Pyran-2-ones from enolates of carbonyl compounds and enaminoesters are described.

The α-oxidation of aryl alkyl ketones using manganese(III) acetate in the presence of various carboxylic acids and (1S)-(+)-10-camphorsulfonic acid provided a convenient synthesis of α-acyloxy, α-(10-camphorsulfonyloxy), and α-hydroxy derivatives in good yield.