Hui-Jing Li

Rearrangement of Dypnones to 1,3,5-Triarylbenzenes

Rearrangement of dypnones to 1,3,5-triarylbenzenes is described. The reaction is proposed to involve an aldol-type self-condensation of dypnones, followed by an intramolecular [2 + 2] cycloaddition and a retro-[2 + 2] cycloaddition. The reaction goes smoothly under obviously milder conditions in comparison to the cyclotrimerization of acetophenones to 1,3,5-triarylbenzenes (10 mol % of TsOH, 80 °C versus 130-148 °C). This unexpected rearrangement would provide new possible considerations in dypnone-involved organic synthesis.

Regioselective 1,2-Diol Rearrangement by Controlling the Loading of BF3·Et2O and Its Application to the Synthesis of Related Nor-Sesquiterene- and Sesquiterene-Type Marine Natural Products

The regiocontrolled rearrangement of 1,2-diols has been achieved by controlling the loading of BF3·Et2O. Its applicability is showcased by the divergent synthesis of austrodoral, austrodoric acid, and 8-epi-11-nordriman-9-one, as well as a formal synthesis of siphonodictyal B and liphagal. A new light is shed on piancol-type rearrangements that will be useful in diversity-oriented synthesis of related natural products.

Protecting-group-free synthesis of haterumadienone- and puupehenone-type marine natural products

A divergent and expeditious access to haterumadienone- and puupehenone-type marine natural products has been achieved by using a newly developed hemiacetalization/dehydroxylation/hydroxylation/retro-hemiacetalization tandem reaction as one of the key steps. Its applicability is showcased by the first synthesis of haterumadienone, 20-hydroxyhaterumadienone, 20-epihydroxy-haterumadienone and 20-acetoxy-haterumadienone, as well as the facile synthesis of puupehenone, puupehedione and puupehenol. The synthesis is efficient, and atom- and step-economical (6 to 9 steps from commercially available starting materials), and requires no protecting groups and transition metals.

Enantiospecific Semisynthesis of Puupehedione-Type Marine Natural Products

An enantiospecific semisynthesis of puupehedione was achieved from sclareolide in only 7 steps with an overall yield of 25%. The key drimanal trimethoxystyrene skeleton was constructed by the palladium-catalyzed cross-coupling reaction of an aryl iodine and a drimanal hydrazone. An in situ CAN-oxidation/intramolecular oxa-Stork-Danheiser transposition tandem reaction was used as a powerful tool to install concurrently the C and D rings of puupehedione in a one-pot fashion. Its applicability was also showcased by the semisynthesis of puupehenone and puupehenol.

Gravimetric, electrochemical and surface studies on the anticorrosive properties of 1-(2-pyridyl)-2-thiourea and 2-(imidazol-2-yl)-pyridine for mild steel in hydrochloric acid

1-(2-Pyridyl)-2-thiourea (TP) and 2-(imidazol-2-yl)-pyridine (IP) are described here for the first time as inhibitors of mild steel corrosion in acidic medium based on investigations such as weight loss tests, potentiodynamic polarization measurements and electrochemical impedance spectroscopy (EIS). The experimental results revealed that 1-(2-pyridyl)-2-thiourea and 2-(imidazol-2-yl)-pyridine are effective corrosion inhibitors for mild steel in acidic medium, and their maximum corrosion inhibition efficiencies at 4 × 10−4 M are 93.57% and 96.66%, respectively. TP and IP are determined as mixed-type inhibitors based on polarization studies, and their adsorption on the mild steel surface follows the Langmuir adsorption isotherm and physical adsorption is dominant. The formation and characteristics of the protective layer on the steel surface were verified by scanning electrochemical microscopy (SECM), UV-visible spectroscopy, FT-IR spectroscopy and X-ray photoelectron spectroscopy (XPS) methods. Besides, the correlation between the inhibition efficiency and the molecular structure of inhibitors was theoretically studied via quantum chemical calculations.

Divergent Synthesis of Marine Natural Products Siphonodictyal B, Corallidictyals C/D and Liphagal Based on the Early Presence of an Aldehyde Group Instead of a Late-Stage Introduction

An iodine-promoted sunlight-induced olefin Z/ E isomerization reaction together with a palladium-catalyzed direct cross-coupling reaction of a drimanal hydrazone and an iodobenzaldehyde, without touching the aromatic aldehyde group, facilitated a divergent and expeditious access to bioactive marine natural products siphonodictyal B, corallidictyals C/D, and liphagal based on the early presence of an aldehyde group instead of a late-stage introduction.

Synthesis of natural product inulavosin via Ga(OTf)3-Catalyzed Hetero Diels–Alder Dimerization of salicyl alcohol derivative

Abstract Inulavosin, a natural melanogenesis inhibitor, has been synthesized smoothly from readily available and inexpensive starting materials by using a Ga(OTf)3-catalyzed room temperature hetero Diels–Alder dimerization of salicyl alcohol derivative and a regioselective phenol monobromination as the key steps. Graphical Abstract

Regioselective synthesis of gentisyl alcohol-type marine natural products

Abstract Gentisyl alcohol-type natural products, possessing various important biological properties, have been synthesized from 4-methoxyphenol by using a selective phenol monohydroxymethylation/monochlorination, a CAN oxidation and a sodium dithionite reduction as the key steps. The natural product synthesis is efficient, atom- and step-economical, and requires no protecting groups.

Adsorption Activity and Molecular Dynamics Study on Anti-corrosion Mechanism of Q235 Steel

The correlation between inhibition efficiency and molecular structures of the inhibitor during hydrochloric acid corrosion of Q235 steel was studied by quantum chemical calculations and molecular dynamics(MD) simulation. The proton affinity(PA) calculations demonstrated that 2-(quinolin-2-yl)quinazolin-4(3H)-one inhibitor has the tendency to be protonated in hydrochloric acid, which was in good agreement with experimental observations. Besides, quantum chemical parameters revealed that the protonated corrosion inhibitor molecules were more easily adsorbed on Q235 steel surface and improved the corrosion resistance of steel. MD simulations were implemented to search for the adsorption behavior of this molecule on Fe (110) surface, which might be used as a convenient tool for estimating the interaction mechanism between inhibitor and iron surface.