N-Alkoxypyrazoles as biomimetics for the alkoxyphenyl group in tamoxifen

Catalytic and catalyst-free diboration of alkynes

The present review provides a comprehensive summary of the catalytic and catalyst-free diboration of alkynes.

Synthesis of Multisubstituted Olefins through Regio- and Stereoselective Addition of Interelement Compounds Having B-Si, B-B, and Cl-S Bonds to Alkynes, and Subsequent Cross-Couplings

Multisubstituted olefins are fundamental motifs in organic compounds. In this account, we describe the synthesis of organic molecules bearing an olefinic moiety by the transition-metal-catalyzed regio- and stereoselective addition of a variety of interelement compounds to alkynes. Regio- and stereoselective silaboration, diborylation, and chlorothiolation have been achieved by using the transition-metal catalysts. The subsequent cross-coupling reactions of the boron-containing alkenes to install various aryl groups afforded the corresponding tri- and tetraarylated olefins. This account describes our research on the highly regio- and stereoselective synthesis of multifunctionalized olefins such as tetraarylethenes with four different aryl groups.

Synthesis and biological evaluation of 4-(aminomethyl)-1-hydroxypyrazole analogues of muscimol as γ-aminobutyric acid(a) receptor agonists

A series of bioisosteric 4-(aminomethyl)-1-hydroxypyrazole (4-AHP) analogues of muscimol, a GABA(A) receptor agonist, has been synthesized and pharmacologically characterized at native and selected recombinant GABA(A) receptors. The unsubstituted 4-AHP analogue (2a) (EC(50) 19 μM, R(max) 69%) was a moderately potent agonist at human α(1)β(2)γ(2) GABA(A) receptors, and in SAR studies substitutions in the 3- and/or 5-position were found to be detrimental to binding affinities. Ligand-receptor docking in an α(1)β(2)γ(2) GABA(A) receptor homology model along with the obtained SAR indicate that 2a and muscimol share a common binding mode, which deviates from the binding mode of the structurally related antagonist series based on 4-(piperidin-4-yl)-1-hydroxypyrazole (4-PHP, 1). Selectivity for α(1)β(2)γ(2) over ρ(1) GABA(A) receptors was observed for the 5-chloro, 5-bromo, and 5-methyl substituted analogues of 2a illustrating that even small differences in structure can give rise to subtype selectivity.

New antiestrogens from a library screen of homoallylic amides, allylic amides, and C-cyclopropylalkylamides

A new structural scaffold for antiestrogens was identified from the cell-based screening of transcriptional regulation properties of a 67-member library of homoallylic amides, allylic amides, and C-cyclopropylalkylamides. C-Cyclopropylalkylamide 3a (O-ethyl-N-{2-[(1S*,2R*)-2-{(R*)-[(diphenylphosphinoyl)amino](phenyl)methyl}cyclopropyl]ethyl}-N-[(4-methylphenyl)sulfonyl]carbamate) had antagonistic activity similar to that of tamoxifen and was further evaluated. Compound 3a inhibited estradiol-induced proliferation of the ER-positive MCF-7 cells but had no effect on ER-negative MDA-MB231 human breast cancer cells. Furthermore, high micromolar concentrations of 3a exhibited minimal cytotoxicity to the ER-negative line. The biological activities of the enantiomers of 3a did not differ from one another nor from that of racemic 3a.