Guichun Yang

Combinatorial synthesis of novel thiourea derivatives on a modified poly(ethylene glycol)

Abstract A modified poly(ethylene glycol) (PEG) has been developed for the soluble polymer-supported combinatorial synthesis of novel thiourea derivatives. Dihydroxy-PEG with an average MW of 4000 was used as soluble polymer supports, a benzoyl residue as spacer, and 4-oxybenzoyl chloride group as the moiety with the reactive functionality. Representative thiourea derivatives were obtained in moderate to high yields with excellent purity from these modified PEG-bound products by cleavage with 6% ammonium water. In each step of the sequence, the PEG-bound products were precipitated in cold Et 2 O and the excessive reagents and by-products were removed by simple filtration. The progress of reaction, purities of the isolation and the configuration of the PEG-bound products were easily monitored by TLC, IR and 1 H NMR

Gewald synthesis of 2-aminothiophenes on a soluble polymer-support

A variety of polysubstituted thiophenes have been prepared via a solvent-free one-pot microwave assisted Gewald reaction using poly (ethylene glycol) as a soluble polymer support.

Green Synthesis of Tetrahydrobenzo[b]Pyrans by Microwave Assisted Multi-Component One-Pot Reactions in PEG-400

Polyethylene glycol is found to be a nontoxic and recyclable reaction medium for the microwave-assisted, multi-component one-pot reactions of aromatic aldehydes with ethyl-2-cyanoacetate and 1,3-cyclohexanedione or 5,5- dimethyl-1,3-cyclohexanedione in the presence of piperidine. This environmentally friendly microwave protocol offers ease of operation and enables recyclability of reaction medium and synthesis of a variety of substituted tetrahydrobenzo[b]pyran derivatives. It is an efficient, promising, and green synthetic strategy to construct tetrahydrobenzo[b]pyran skeleton.

Novel Synthesis of 3‐Substituted 2‐Thiohydantoins via Aza‐Wittig Reaction on Poly(ethylene Glycol)

Abstract A novel method for the liquid‐phase combinatorial synthesis of 3‐substituted‐2‐thiohydantoin has been developed by using poly (ethylene glycol)–supported isothiocyanate. The PEG‐supported isothiocyanate was obtained from the reaction of PEG with bromoacetyl bromide, followed by an aza‐Wittig reaction. Reaction of PEG‐supported isothiocyanate with various aliphatic amines offered 3‐substituted 2‐thiohydantoins in excellent yields with addition, cyclization, and cleavage reactions occurred in one pot.

A Ratiometric Fluorescent Probe for Monitoring Leucine Aminopeptidase in Living Cells and Zebrafish Model

Leucine aminopeptidase (LAP) is an important cancer-related biomarker, which shows significant overexpression in malignant tumor cells like liver cancer. Developing an effective method to monitor LAP in tumor cells holds great potential for cancer diagnosis, treatment, and management. In this work, we report a novel BODIPY-based fluorescent probe (BODIPY-C-Leu) capable of monitoring LAP in vitro and in vivo in both ratiometric and turn-on model. BODIPY-C-Leu contains an asymmetrical BODIPY dye for fluorescent signaling and a dipeptide (Cys-Leu) as the triggered moiety. Activation occurs by cleavage of the amide bond in dipeptides and subsequently an intramolecular S → N conversion to convert sulfur-substituted BODIPY to amino-substituted BODIPY, resulting in a dramatic fluorescence variation to realize the detection of LAP. Furthermore, we have successfully employed BODIPY-C-Leu to monitor LAP activity in different cancer cells, indicating that HeLa cells have a higher level of LAP activity than A549 cells. Importantly, we demonstrated the capability of the probe for real-time monitoring the drug-induced LAP level changes in zebrafish.

NOVEL SYNTHESIS OF MONOETHERS OF HYDROQUINONE AND RESORCINOL ON SOLUBLE POLYMER-SUPPORTS

ABSTRACT Monoethers of hydroquinone and resorcinol were easily prepared using PEG as soluble polymer-supports, monoprotection group and phase transfer catalyst with good yields and high selectivity of functionlization in homogenous solution.

Synthesis of Methyl N‐Aryl Oxamate Using Soluble Polymer Support

Abstract A variety of methyl N‐aryl oxamates were synthesized using poly(ethylene glycol) (PEG) as a soluble polymer support and a monoproctection group with excellent yields.

Soluble Polymer-Supported Synthesis of α-Amino Acid Derivatives

Abstract A practical and efficient synthesis of N-substituted α-amino acid derivatives on soluble polymer support is described.

Soluble Polymer-Supported Synthesis of Tertiary Amines

Abstract The synthesis of tertiary amines on a modified soluble polymer, poly(ethylene glycol) (PEG), is described. The PEG-bound quaternary intermediates were assembled via Michael addition reaction, followed by alkylation. Cleavage from the soluble polymer support was induced by insoluble weak basic resin, to afford the target tertiary amines in excellent purity.

(S)-1-[(S)-4-Benzyl-2-thioxothia­zolidin-3-yl]-3-hydroxy­butan-1-one

The title compound, C14H17NO2S2, was synthesized by asymmetric aldol condensation of N-acylthiazolidinethione with acetaldehyde. In the molecule, the thiazolidine five-membered ring assumes an envelope conformation. Intermolecular C—H⋯O and intramolecular O—H⋯O and C—H⋯S hydrogen bonding helps to stabilize the structure.