Facile preparation of aromatic esters from aromatic bromides with ethyl formate or DMF and molecular iodine via aryllithium

A one-pot successive cyclization-alkylation strategy for the synthesis of 2,3-disubstituted benzo[b]thiophenes

In this study, a new environmentally benign iodine-mediated one-pot iodocyclization/alkylation strategy for the synthesis of benzo[b]thiophene derivatives starting from 2-alkynylthioanisoles was developed. The synthesis of a diverse population of 2,3-disubstituted benzo[b]thiophenes was achieved in high yields by employing moderate reaction conditions using 1,3-dicarbonyl substrates as the nucleophile and various substituted propargyl alcohols as both the cyclization precursor and the alkylating agent. This method resulted in the formation of a series of complex structures obtained in a single step. Additionally, a strategy was devised for the one pot iodocyclization/oxidation of propargyl alcohols into carbonyl functionalized benzo[b]thiophene structures. These green one-pot reaction processes were designed to reduce wastes and byproducts while generating a complex substitution pattern on the benzo[b]thiophene structure. The reported methodologies may be used to synthesize more functionalized benzo[b]thiophene structures that can be used in both biomedical and organic electronic applications.

Palladium-Catalyzed, Copper(I)-Promoted Methoxycarbonylation of Arylboronic Acids with O-Methyl S-Aryl Thiocarbonates

Here, we report O-methyl S-aryl thiocarbonates as a versatile esterification reagent for palladium-catalyzed methoxycarbonylation of arylboronic acid in the presence of copper(I) thiophene-2-carboxylate (CuTC). The reaction condition is mild, and a variety of substituents including sensitive -Cl, -Br, and free -NH₂ could be tolerated. Further applications in the late-stage esterification of some pharmaceutical drugs demonstrate the broad utility of this method.

Amberlyst-15 catalysed oxidative esterification of aldehydes using a H2O2 trapped oxidant as a terminal oxidant

A simple and efficient method has been developed for the selective oxidative esterification of aldehydes using commercially available Amberlyst-15 as a catalyst.

Kinetics and mechanism for chlorine-initiated atmospheric oxidation of ethyl formate

The chlorine-initiated reaction mechanism of ethyl formate in the atmosphere was investigated using the density functional theory method. The geometry parameters and frequencies of all of the stationary points were calculated at the B3LYP/ 6-31G(d,p) level. The single-point energy calculations were carried out at different levels, including MP2/6-31G(d), MP2/6-311++G(d,p), and CCSD(T)/6-31G(d). A detailed oxidation mechanism is provided and discussed. Present results show that α-ester rearrangement reaction and the O2 direct abstraction from IM6 (HC(O)OCH(O)CH3) are the more favorable pathway and are competitive. The 1,4-H shift isomerization of IM6 proved to be feasible under general atmospheric conditions. The decomposition of IM18 (CH3CH2OC(O)O) is favorable both thermodynamically and kinetically. Canonical variational transition theory with small-curvature tunneling correction was employed to predict the rate constants. The overall rate constant of ethyl formate at 298 K is 8.63 × 10−12 cm3 molecule−1 s−1. The Arrhenius equations of rate constants at the temperature range of 200–380 K were fitted.

Preparation of 3,5-disubstituted pyrazoles and isoxazoles from terminal alkynes, aldehydes, hydrazines, and hydroxylamine

The reaction of terminal alkynes with n-BuLi, and then with aldehydes, followed by the treatment with molecular iodine, and subsequently hydrazines or hydroxylamine provided the corresponding 3,5-disubstituted pyrazoles or isoxazoles in good yields with high regioselectivity, through the formations of propargyl secondary alkoxides and α-alkynyl ketones. The present reactions are one-pot preparation of 3,5-disubstituted pyrazoles from terminal alkynes, aldehydes, molecular iodine, and hydrazines, and 3,5-disubstituted isoxazoles from terminal alkynes, aldehydes, molecular iodine, and hydroxylamine.