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A novel guanidination method of converting a peptide side chain amino group to a guanidino group on a solid support is described. Four guanidinating reagents were evaluated using a model tetrapeptide attached to a polystyrene resin. Experimental data indicate that the two nitroguanidinating reagents, but not the two tosylguanidinating reagents, can be used effectively in solid phase peptide synthesis.

We have examined the effect of C α -methyl groups on the conformational ensemble of GnRH analog peptides by comparing 1 2D NMR data from two analogs, Ac-D-Nal 1 -D-4-Cl-C α -Me-Phe 2 -D-Pal 3 -Ser 4 -Tyr 5 -D-Arg 6 -Leu 7 -Arg 8 -Pro 9 -D-Ala 10 -NH 2 (1) and Ac-D-Nal 1 -D-4-Cl-C α -Me-Phe 2 -D-Pal 3 -Ser 4 -C α -Me-Tyr 5 -D-Arg 6 -Leu 7 -C α -Me-Arg 8 -Pro 9 -D-Ala 10 -NH 2 (2). The two additional C α -methyl groups in residues 5 and 8 of 2 do not influence significantly the pattern of the observable main chain NOE intensities, or of the backbone HN proton chemical shifts, which indicates that they do not produce global changes in the conformational ensemble of the peptide. A local change induced by the substitution was observed in the conformation at D-Arg 8 -Pro 9

Optically pure L-(+)-C alpha-methyl-arginine and D-(-)-C alpha-methyl-arginine were synthesized. Experimental results indicated that DL-C alpha-methyl-arginine methyl ester could be resolved by trypsin, but workup posed a technical difficulty. Chemical resolution at the stage of DL-C alpha-methyl-ornithine, followed by selective guanidination using N,N'-di-Cbz-S-methylisothiourea and hydrogenolysis provided a effective and practical method for the synthesis of optically pure C alpha-methyl-arginine.

A practical and convenient procedure for making phosphotyrosine-containing peptides by the solid-phase method was developed. Phosphotyrosine was incorporated via Boc-Tyr(PO3Bzl2)-OH. The completed peptide was cleaved from the solid support by treatment with 1 M TMSBr-thioanisole-TFA. By gel-phase 31P-NMR spectroscopy we found that one of the benzyl protecting groups on phosphate was completely removed by two consecutive runs of Boc deprotection with 50% TFA-DCM. However, the other benzyl group remained intact throughout the synthesis (35 cycles).

Much has been learned about the consequences of glucocorticoid receptor antagonism by studying steroidal active antagonists such as RU-38486 (1). In the liver glucocorticoid receptor antagonism suppresses hepatic glucose production decreasing plasma glucose levels; however, extrahepatic antagonism produces several undesirable side effects including activation of the hypothalamic pituitary adrenal axis. A series of nonsteroidal passive N-(3-dibenzylamino-2-alkyl-phenyl)-methanesulfonamide glucocorticoid receptor modulators was discovered. Liver selective and systemically available members of this series were found and characterized in diabetes and side effect rodent models. A highly liver selective member of this series, acid 14, shows efficacy in the ob/ob model of diabetes. It lowers plasma glucose, cholesterol, and free fatty acid concentrations and reduces the rate of body weight gain. The structurally related systemically available passive modulator 12 lowers glucose, HbA(1c), triglyceride, free fatty acid, and cholesterol levels. Interestingly, it did not acutely activate the hypothalamic pituitary adrenal axis in unstressed CD-1 mice or have the abortive effects observed with 1. These results indicate that passive GR antagonists may have utility as antidiabetic agents.

A practical synthesis of neuraminidase influenza inhibitor, A-322278, has been developed. Asymmetry is introduced into the synthesis by an enzyme mediated ester hydrolysis. A highly diastereoselective vinylogous Mannich condensation reaction of N-Boc-2-tert-butyldimethylsilyloxypyrrole (TBSOP) and an N-(triphenylmethylsulfenyl)imine proceeds under thermodynamic control to assemble the framework. A significant temperature dependent rate difference for the transfer of (Z)- and (E)-propenyl moieties from a cuprate reagent during a 1,4-conjugate addition was observed. A very selective addition of cyanide to an N-acyliminium intermediate was employed to control the final stereocenter.

A process for the preparation of matrix metalloproteinase inhibitor ABT-518 has been developed. Significant improvements have been made to the first generation synthesis and are described here. The new process is very robust and efficient; multikilogram quantities of the title compound have been synthesized for clinical trials. ABT-518 was prepared by this six-step synthetic sequence in 51% overall yield with >99% ee.

A procedure for the efficient direct guanylation of peptides has been developed. A model peptide was guanylated directly using (ethylamino)(ethylimino) methanesulfonic acid.

A safe, reliable and scalable process for the preparation of N-Boc-2-tert-butyldimethylsiloxy-pyrrole (TBSOP) is described. In a three-step, one-pot sequence (±)-4-amino-3-hydroxybutyric acid was converted to N-Boc-4-hydroxy-2-pyrrolidinone. This stable crystalline product was isolated by filtration directly from the reaction mixture. Dehydration followed by enolization and silylation produced the target compound without the need for chromatographic purification. The process was demonstrated in the pilot plant to make multikilogram quantities of material in 85% overall yield.

A mild N-alkylation method has been developed for the synthesis of N-alkylated pyridiniumcarboxylic acids, using Ag2O-H2O catalysis to enhance the low-reactivity of pyridinecarboxylic acids. Two approaches were undertaken for the synthesis of a series of GnRH antagonists containing pyridinium moieties at the side chain: (1) incorporation of Npy-alkylated D-pyridylalanine during solid phase peptide chain assembly, and (2) coupling of the N-alkylated pyridinium-carboxylic acid to the resin-bound e-amino group of a D-lysine on a solid support.

Amino- and guanidinoacyl esters of ryanodine were prepared to evaluate the effect of basicity on the binding affinity of these derivatives for the sarcoplasmic reticulum Ca(2+)-release channel (SR CRC). In the presence of DCC and DMAP Cbz-beta-alanine reacts with ryanodine in CH2Cl2 to give O10eq-Cbz-beta-alanylryanodine (3a), which on hydrogenolysis yields the beta-alanyl ester (4a). N,N'-bis-Cbz-S-methylthiourea reacts with 4a to yield beta-N,N'-bis-Cbz-guanidinopropionylryanodine (5a). O10eq-beta-guanidinopropionylryanodine (6a) is obtained on hydrogenolytic deprotection of 5a. The binding affinity of beta-alanine ester (4a) and its glycyl congener (4b) is 2-3-fold greater, and that of the beta-guanidinopropionyl ester (6a) and its acetyl congener (6b) 3-6-fold greater, than that of ryanodine. The effect of ryanodine on SR Ca2+ flux is of a biphasic nature: nanomolar levels open (activate) the channel, while micromolar levels close (deactivate) it. The base-substituted esters 4a and 6a both display a unidirectional effect: they only open the channel. An understanding of ryanodine's mode of action and the design of effective SR CRC activating and deactivating ryanoids for possible therapeutic application are major research objectives.

A novel guanidination method of converting a peptide side chain amino group to a guanidino group on a solid support is described. Four guanidinating reagents were evaluated using a model tetrapeptide attached to a polystyrene resin. Experimental data indicate that the two nitroguanidinating reagents, but not the two tosylguanidinating reagents, can be used effectively in solid phase peptide synthesis.

A mild N-alkylation method has been developed for the synthesis of N-alkylated pyridiniumcarboxylic acids, using Ag2O-H2O catalysis to enhance the low-reactivity of pyridinecarboxylic acids. Two approaches were undertaken for the synthesis of a series of GnRH antagonists containing pyridinium moieties at the side chain: (1) incorporation of Npy-alkylated D-pyridylalanine during solid phase peptide chain assembly, and (2) coupling of the N-alkylated pyridinium-carboxylic acid to the resin-bound e-amino group of a D-lysine on a solid support.

A procedure for the efficient direct guanylation of peptides has been developed. A model peptide was guanylated directly using (ethylamino)(ethylimino) methanesulfonic acid.

Diastereomers formed by precolumn derivatization of d,l -α-methyl amino acids with 2,3,4,6-tetra-O-acetyl-β- d -glucopyranosylisothiocyanate (GTIC) were separated by high-performance liquid chroamtography using a conventional C18 reversed-phase column. This method completely resolved all the α-methyl amino acids tested except d,l -4-chloro-α-methylphenylalanines which were less well separated. The d -enantiomer was eluted earlier than the l -enantiomer, which is opposite to the order of elution observed with GITC derivative of unmethylated amino acids.

A novel series of pyrrolidine-constrained phenethylamines were developed as dipeptidyl peptidase IV (DPP4) inhibitors for the treatment of type 2 diabetes. The cyclohexene ring of lead-like screening hit 5 was replaced with a pyrrolidine to enable parallel chemistry, and protein co-crystal structural data guided the optimization of N-substituents. Employing this strategy, a >400x improvement in potency over the initial hit was realized in rapid fashion. Optimized compounds are potent and selective inhibitors with excellent pharmacokinetic profiles. Compound 30 was efficacious in vivo, lowering blood glucose in ZDF rats that were allowed to feed freely on a mixed meal.

An efficient and practical synthetic procedure is described for the preparation of a variety of N-substituted aryl- and alkyl-2-aminobenzoxazoles. This new method offers broad utility and provides desired products in good to excellent yield. The title compounds are formed in a one-pot, two step reaction sequence that is safe and operationally straightforward.

Seismic modeling is one of the basic tools to link the geology to the seismology. By means of the physical and numerical seismic modeling, geologists and geophysicists can better understand the relationship of the seismic data to the various geologic discontinuities. In general, seismic modeling can be employed to design the seismic acquisition parameters, prove the seismic processing approaches and validate the seismic interpretation. In our research, however, we just pay attention to the application of seismic modeling to seismic interpretation. In order to meet the requirement of the interpretation of the Kela 2 gas field, Tarim basin, northwest China, we develop a so-called “flexible exploding reflector” method to create synthetic stack section. By this method, we solve two reflection uncertainties in interpretation, find out the reflection characters of the target horizon and get the necessary condition to generate the flat spot in stack section. The successful application of the seismic modeling in the interpretation of the Kela 2 gas field left no doubt as to the fact that seismic modeling will be more beneficial to seismic interpretation in complicated geological setting.

Summary The problems induced by rugged topography in seismic data processing has attracted geophysicist’s more and more attention in recent years. Some approaches about the S/N ratio, static correction, wave-equation datuming , stack and migration have achieved in order to attenuate the effect of the rugged surface. But there are still some problems needed to be further researched, such as seismic numerical modeling. By the means of seismic numerical modeling, we can investigate the wave generation and propagation in detail and obtain numerical seismic gathers or section for validation of seismic data processing and seismic data interpretation. In this paper, we employ the finite element method based on hybrid element technique and develop a boundary condition and a corner condition to simulate the acoustic wave propagation numerically. The hybrid element technique uses both of the triangular and rectangular elements to dissect the computational area with rugged surface and extend the mass and stiffness matrices of triangular element to those of rectangular element in form for computational unity. In order to eliminate the boundary reflection on the boundary and at corner better, we introduce a boundary condition which contains a parameter, the incident angle, and develop a corner condition which considers both of the up or down going wave and lef t or rightoing wave.ery encouraging results have been obtained on theoretical and real models .

Volitinib is a novel selective cMet inhibitor. This study is to evaluate its preclinical ADME/PK profile. Volitinib has high membrane permeability (Papp (A>B) 28×10−6 cm/s) without efflux transport across Caco-2 cell monolayer and exhibits negligible P-gp inhibition (IC50 > 17 μM). Metabolic stability of volitinib in liver microsomes and S9 fractions of rat, dog, monkey and human was evaluated. Five phase I metabolites were observed in liver microsomes and S9 fractions of different species, and three major metabolites resulted from demethylation (M1), hydroxylation (M2) and mono-oxygenation (M3) were found to be mediated by multiple enzymes, including CYP450s and aldehyde oxidase. Rat was the most similar species to human in terms of the in vitro metabolism and metabolite profile. Metabolism is the main route of elimination for volitinib in rat due to the fact that the fecal, urinary and biliary excretion of the parent volitinib accounted for Citation Format: Yi Gu, Yang Sai, Jian Wang, Sumei Xia, Guanglin Wang, Yuansheng Zhao, Li Zhang, Wenqing Yang, Guangxiu Dai, Weihan Zhang, Qisun Gong, Zhenping Tian, Weiguo Su. Preclinical disposition and pharmacokinetics of volitinib, a novel selective cMet inhibitor . [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3371. doi:10.1158/1538-7445.AM2013-3371

About 25 conformationally constrained antagonists of LHRH have been synthesized in order to gain some information about the bioactive conformation of antagonists. The constraints include various C-methyl residues, N-methyl groups, prolines and the 6-7 lactam. The antagonists were evaluated in the rat antiovulatory assay, in a pituitary cell membrane binding assay and by NMR. The results will be discussed and a model of the bioactive conformation proposed.