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This study aimed to develop a simple fluorescent probe for detecting glutathione (GSH) over cysteine (Cys) and homocysteine (Hcy). To this end, two fluorescent probes HPY1, 2 that used pyrazoline as the fluorophore and an acrylate group as the recognition group for thiols were designed and synthesized. HPY1, 2 possessed excellent sensitivity, high selectivity and great stability for detecting GSH. The detection limit of HPY1, 2 for GSH was found to be 2.06 × 10-7 M, 1.36 × 10-7 M respectively. The recognition mechanism of HPY1, 2 to GSH were studied by fluorescence change experiments, HRMS and DFT calculation, which elucidated that HPY1, 2 and GSH could undergo Michael addition reaction to generate strongly fluorescent addition products. Additionally, HPY1 was successfully applied to imaging of both endogenous and exogenous GSH in L929 cells based on its low cytotoxicity and good cell permeability. This wok indicated that HPY1, 2 have a great potential for application in detection of GSH.

We describe an efficient synthesis of 2,4-substituted pyrido[4,3-d]pyrimidin-5(6H)-ones, which involves the acid-promoted cyclization of cyano enamine 15 to afford 2,4-bis(methylthio)pyrido[4,3-d]pyrimidin-5(6H)-one 17 as a key intermediate. Selective displacement of the 4-methylthio group by a wide range of anilines followed by oxidation of the 2-methylthio group and subsequent substitution by amines enabled the synthesis of a variety of 2,4-disubstituted pyrido[4,3-d]pyrimidin-5(6H)-ones.

A biomimetic synthesis of the triterpene (±)-perovskone was achieved featuring a remarkable polycyclization process in which three rings, four bonds, and five stereocenters were created in a single operation in 82% yield. This convergent synthesis required 16 steps, starting from vanillin, and proceeded in 9% overall yield. A second route to prepare optically active quinone 2 took 15 steps in 36% overall yield and featured a palladium-catalyzed reductive allylic transposition to establish the C-5 chirality stereospecifically. Quinone (−)-2 was converted to (+)-perovskone (1) via a polycyclization cascade, which created four rings, five bonds, and six stereocenters in a single operation in 50% yield.

The first synthesis of Tic-D-Phe Psi[CH(2)-CH(2)] isostere is described, which features diastereoselective alkylation of the tricyclic lactam 14. The use of this novel dipeptide isostere in the development of melanocortin agonists has been demonstrated by the synthesis of peptidomimetic 7 and non-peptidic ligand 27. Both compounds displayed significant binding and agonist potency at the MC4R.

A series of proline based melanocortin ligands has been developed on the basis of initial piperazine leads by using a more conformationally rigid scaffold. A number of these novel ligands showed significant binding affinity for MC3 and MC4 receptors.

Asymmetric Michael reaction of phosphinic or aminophosphinic acids with acrylate derivatives afforded phosphinyl dipeptidomimetics in excellent yields (>90%). Chiral induction of substituents at the α-position of acrylate derivatives of Evans oxazolidinone type auxiliaries was obtained in moderate to excellent diastereomeric and enantiomeric excesses (50–98%). Pure diastereomers and enantiomers of phosphinyl dipeptidomimetics 16 – 19 were also successfully separated by HPLC.

A series of compounds related to N-butyl-N-ethyl[2,5,6-trimethyl-7-(2,4,6-trimethylphenyl)pyrrolo[2,3-d]pyrimidin-4-yl]amine (1, antalarmin) have been prepared and evaluated for their CRHR1 binding affinity as the initial step in the development of selective high affinity hydrophilic nonpeptide corticotropin-releasing hormone type 1 receptor (CRHR1) antagonists. Calculated log P (Clog P) values were used to evaluate the rank order of hydrophilicity for these analogues. Introducing oxygenated functionalities (delta-hydroxy or bis-beta-ethereal) into 1 gave more hydrophilic compounds, which had good affinity for the receptor. Introducing an amino group or shortening the alkyl side chain was detrimental to CRHR1 affinity. The alcohol 4-[ethyl[2,5,6-trimethyl-7-(2,4,6-trimethylphenyl)pyrrolo[2,3-d]pyrimidin-4-yl]amino]butan-1-ol (3), bearing a terminal hydroxyl group on an N-alkyl side-chain, showed the highest CRHR1 binding affinity among these compounds (K(i)=0.68 nM), and is one of the highest affinity CRHR1 ligands known. Compounds 3-5, and 8, which are likely to be less lipophilic than 1, have high CRHR1 affinity and may be valuable probes to further study the CRH system.

A high-affinity radioligand for CRHR1 has been prepared that can serve as a template for the development of SPECT imaging agents. The 5-chloro-N-cyclopropylmethyl-N-(2,6-dichloro-4-iodophenyl)-2-methyl-N-propylpyrimidine-4,6-diamine (6b, Ki=14 nM), and the corresponding 4-bromophenyl analogue (6a, Ki=21 nM), were synthesized in four steps from compound 3.