A Pericyclic Reaction in the Gas Phase Identified by Rotational Spectroscopy: Reaction of a Thiocarboxylic Acid with Sulfur Trioxide.

The reaction of sulfur trioxide (SO) and thiobenzoic acid (CHCOSH) is investigated in the gas phase under supersonic jet conditions. Rotational spectroscopy of the parent and several isotopically substituted derivatives, in conjunction with DFT calculations at the M06-2X/6-311++G(3df,3pd) level of theory, identify the product as thiobenzoic sulfuric anhydride, CHC(=S)OSOOH. Single point CCSD(T)/CBS(D-T)//M06-2X/6-311++G(3df,3pd) calculations place the electronic energy of the product anhydride 114 kJ/mol lower than that of SO+CHCOSH at infinite separation.

Partial Proton Transfer in the Gas Phase: A Spectroscopic and Computational Analysis of the Trifluoroacetic Acid - Trimethylamine Complex.

The 1:1 complex formed from trifluoroacetic acid (TFA) and trimethylamine (TMA) has been observed in the gas phase by rotational spectroscopy and further investigated by DFT and MP2 methods. Spectra of both the parent form and the -OD isotopologue have been obtained. The complex is structurally similar to a hydrogen bonded system, with the O-H bond directed toward the nitrogen of the TMA.

Trishomocubane as a scaffold for the development of selective dopamine transporter (DAT) ligands.

In our continued exploration of trishomocubane derivatives with central nervous system (CNS) activity, N-arylalkyl-8-aminopentacyclo[5.4.0.

Design, synthesis, and structure-affinity relationships of regioisomeric N-benzyl alkyl ether piperazine derivatives as sigma-1 receptor ligands.

A series of N-(benzofuran-2-ylmethyl)-N'-benzylpiperazines bearing alkyl or fluoroalkyl aryl ethers were synthesized and evaluated at various central nervous system receptors. Examination of in vitro sigma1 {[3H]+-pentazocine} and sigma2 ([3H]DTG) receptor binding profiles of piperazines 11-13 and 25-36 revealed several highly potent and sigma1 selective ligands, notably, N-(benzofuran-2-ylmethyl)-N'-(4'-methoxybenzyl)piperazine (13, Ki=2.7 nM, sigma2/sigma1=38) and N-(benzofuran-2-ylmethyl)-N'-(4'-(2''-fluoroethoxy)benzyl)piperazine (30, Ki=2.

Extracellular loops 2 and 4 of GLYT2 are required for N-arachidonylglycine inhibition of glycine transport.

Concentrations of extracellular glycine in the central nervous system are regulated by Na(+)/Cl(-)-dependent glycine transporters, GLYT1 and GLYT2. N-Arachidonylglycine (NAGly) is an endogenous inhibitor of GLYT2 with little or no effect on GLYT1 and is analgesic in rat models of neuropathic and inflammatory pain. Understanding the molecular basis of NAGly interactions with GLYT2 may allow for the development of novel therapeutics.

Selective recognition of pyrophosphate in water using a backbone modified cyclic peptide receptor.

A cyclic peptide based receptor, bearing two dipicolylamino arms complexed to zinc(II) ions, binds pyrophosphate ions with high affinity and selectivity in aqueous solution as determined using an indicator displacement assay.

Synthetic peptides with selective affinity for apoptotic cells.

The appearance of anionic phosphatidylserine (PS) in the outer monolayer of the plasma membrane is a universal indicator of the early/intermediate stages of cell apoptosis. The most common method of detecting PS on a cell surface is to use the protein annexin V; however, in certain applications there is a need for alternative reagents. Recent research indicates that rationally designed zinc 2,2'-dipicolylamine (Zn2+-DPA) coordination complexes can mimic the apoptosis sensing function of annexin V.

Radical carboxyarylation approach to lignans. Total synthesis of (-)-arctigenin, (-)-matairesinol, and related natural products.

[reaction: see text] Total syntheses of seven biologically important lignan natural products, including (-)-arctigenin, (-)-matairesinol, and (-)-alpha-conidendrin, by way of a highly stereoselective domino radical sequence is presented. The reported stereochemistry of the natural product 7-hydroxyarctigenin is shown to be erroneous; a diastereoisomeric structure is assigned to the natural product.

The intramolecular carboxyarylation approach to podophyllotoxin.

Since 1960, only seven plant-derived anticancer drugs have received FDA approval for commercial production. Two are semisynthetic derivatives of podophyllotoxin. This paper describes concise, highly convergent, and conceptually novel approaches to (-)-podophyllotoxin and its enantiomer.