We designed, prepared, and characterized three cup-shaped cavitands 1-3 for trapping organophosphonates (O═PR(OR')2, 118-197 Å(3)) whose shape and size correspond to G-type chemical warfare agents (132-186 Å(3)). With the assistance of computational (molecular dynamics) and experimental ((1)H NMR spectroscopy) methods, we found that host [1-H3](3+) orients its protonated histamine residues at the rim outside the cavity, in bulk water. In this unfolded form, the cavitand traps a series of organophosphonates 5-13 (K(app) = 87 ± 1 to 321 ± 6 M(-1) at 298.0 K), thereby placing the P-CH3 functional group in the inner space of the host. A comparison of experimental and computed (1)H NMR chemical shifts of both hosts and guests allowed us to derive structure-activity relationships and deduce that, upon the complexation, the more sizable P-OR functional groups in guests drive organophosphonates to the northern portion of the basket [1-H3](3+). This, in turn, causes a displacement of the guest's P-CH3 group and a contraction of the cup-shaped scaffold. The proposed induced-fit model of the recognition is important for turning these modular hosts into useful receptors capable of a selective detection/degradation of organophosphorus nerve agents.

Drug design and development is a central thrust of current research. Thus, it is imperative that students pursuing degrees in a variety of chemical and biological fields become exposed to the research and development process early in their curriculum. The organic chemistry laboratory course, required for many prehealth professional degree programs in biology and related fields, is well-suited for a first introduction to processes critical to the development of pharmaceuticals. While all of the components of research and development would encompass a multitude of coursework, focusing on aspects of ligand design, an important aspect of drug research and development, led by molecular modeling (computer-aided drug design), is ideal for a multiweek project during the second semester organic laboratory course. By using free, accessible online software like PatchDock, Chimera, and SwissADME, students are led through a manageable drug design project focused on generating noncovalent inhibitors of acetylcholinesterase (AChE) derived from known therapeutics. Not only do students dock their own unique inhibitors, but also they are led through gathering important toxicological data points through modeling with SwissADME. Overall, students are given the opportunity to see features of the drug design process beyond the synthesis of complex organic molecules within a research-like environment.

Aging is a dealkylation reaction of organophosphorus (OP)-inhibited acetylcholinesterase (AChE). Despite many studies to date, aged AChE cannot be reactivated directly by traditional pyridinium oximes. This review summarizes strategies that are potentially valuable in the treatment against aging in OP poisoning. Among them, retardation of aging seeks to lower the rate of aging through the use of AChE effectors. These drugs should be administered before AChE is completely aged. For postaging treatment, realkylation of aged AChE by appropriate alkylators may pave the way for oxime treatment by neutralizing the oxyanion at the active site of aged AChE. The other two strategies, upregulation of AChE expression and introduction of exogenous AChE, cannot resurrect aged AChE but may compensate for lowered active AChE levels by in situ production or external introduction of active AChE. Upregulation of AChE expression can be triggered by some peptides. Sources of exogenous AChE can be whole blood or purified AChE, either from human or nonhuman species.

After the inhibition of acetylcholinesterase (AChE) by organophosphorus (OP) nerve agents, a dealkylation reaction of the phosphylated serine, referred to as aging, can occur. When aged, known reactivators of OP-inhibited AChE are no longer effective. Realkylation of aged AChE may provide a route to reversing aging. We designed and synthesized a library of quinone methide precursors (QMPs) as proposed realkylators of aged AChE. Our lead compound (C8) from an in vitro screen successfully resurrected 32.7 and 20.4% of the activity of methylphosphonate-aged and isopropyl phosphate-aged electric-eel AChE, respectively, after 4 days. C8 displays properties of both resurrection (recovery from the aged to the native state) and reactivation (recovery from the inhibited to the native state). Resurrection of methylphosphonate-aged AChE by C8 was significantly pH-dependent, recovering 21% of activity at 4 mM and pH 9 after only 1 day. C8 is also effective against isopropyl phosphate-aged human AChE.

We have developed a novel synthetic method that enables the preparation of functional derivatives of heptiptycene, i.e., cavitands with two juxtaposed cavities. The homocoupling of bicyclic dibromoalkenes is promoted by Pd(OAc)2 (10%) in dioxane (100 °C) to give cyclotrimers in 27-77% yield under optimized reaction conditions (Ph3P, K2CO3, n-Bu4NBr, N2, 4 Å MS). These dual-cavity baskets show a strong π → π* absorption at 241 nm (ε = 939,000 M(-1) cm(-1)), along with a subsequent fluorescence emission at 305 nm.

Acetylcholinesterase (AChE) is an essential enzyme that can be targeted by organophosphorus (OP) compounds, including nerve agents. Following exposure to OPs, AChE becomes phosphylated (inhibited) and undergoes a subsequent aging process where the OP-AChE adduct is dealkylated. The aged AChE is unable to hydrolyze acetylcholine, resulting in accumulation of the neurotransmitter in the central nervous system (CNS) and elsewhere. Current therapeutics are only capable of reactivating inhibited AChE. There are no known therapeutic agents to reverse the aging process or treat aged AChE. Quinone methides (QMs) have been shown to alkylate phosphates under physiological conditions. In this study, a small library of novel quinone methide precursors (QMPs) has been synthesized and examined as potential alkylating agents against model nucleophiles, including a model phosphonate. Computational studies have been performed to evaluate the affinity of QMPs for the aged AChE active site, and preliminary testing with electric eel AChE has been performed.

Regio- and stereoselective alkane dehydrogenation is a difficult challenge in organometallic chemistry. Intermolecular reactions of this type typically produce numerous olefin stereo- and regioisomers. Herein, we report our initial investigations into the intramolecular dehydrogenation of a datively bound alkyl ligand, demonstrating the first example of a site-selective dehydrogenation of an unactivated acyclic alkyl group. The alkyl group is located on an acylphosphine ligand that is coordinated to a Cp*IrCl2 monomer. A mechanistic proposal, guided by the isolation of a dimeric iridium complex and supported by computational results, is also described.

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