Professor Athelstan Beckwith, FRACI, FAA, FRS, OA passed away on 15th May 2010. He was a giant of Australian Chemistry and his contributions to the field of physical organic chemistry and free radical research have had major impacts worldwide. Athel published over 200 papers which have received more than 9900 citations. He was a great supporter of the Australian Journal of Chemistry, publishing more articles in our journal than anywhere else. This Special Issue of the Australian Journal of Chemistry is dedicated to him.

The late Professor Athel Beckwith made many significant contributions to the emergence of free radicals as controllable and selective reactive intermediates in synthesis. This account revisits his early mechanistic studies on the cyclization of hex-5-enyl radical systems, considered to be his most important work and the springboard for a multitude of applications in the synthesis of polycyclic natural products and related compounds.

The cyclohexanedione oxime ether herbicides are an important and widely used class of weed-control agents that selectively kill grass species. A brief overview of the cyclohexanedione herbicide field is given together with a more detailed account of the discovery and development of the herbicide butroxydim.

Nitroxides serve as probes of oxidative change and free radical reactions. When closely linked to a fluorescent moiety, the nitroxide suppresses the normal fluorescence emission process. Free radical scavenging, metabolism or redox chemistry, however, return the system to its fluorescent state, and so these molecules are powerful fluorometric probes for radical processes.

Conjugation of multiple bonds does not always impart thermodynamic stabilization by resonance delocalization, even in the absence of any steric effects. Substantial destabilizations are found in cyanogen and in α-dicarbonyls.

High-level theoretical procedures were employed to obtain O–H bond dissociation energies (BDEs) of chemical accuracy. The effects of substituents on the BDEs were examined. We find that the stabilities of both ROH and RO• play important roles in determining the BDEs.

Electron-withdrawing substituents, hydrogen bonding and protonation at the amide nitrogen destabilize radicals formed by loss of a C–H adjacent to the amide nitrogen, typically by 10–20 kJ mol^–1, and stabilize radicals formed by loss of a C–H adjacent to the amide carbonyl, typically by 5–10 kJ mol^–1.

The acyl radical cyclization of β-disubstituted acrylates under polarity-reversal catalysis conditions has afforded a series of dioxaspiro heterocycles including dihydrolongianone. Decarbonylation of the acyl radical intermediates has been identified as a competing pathway in this process.

Nitroxides serve as probes of oxidative change and free radical reactions. When closely linked to a fluorescent moiety, the nitroxide suppresses the normal fluorescence emission process. Free radical scavenging, metabolism or redox chemistry, however, return the system to its fluorescent state, and so these molecules are powerful fluorometric probes for radical processes.

Profluorescent nitroxides (PFNs) are a more recent addition to the ever-increasing bank of nitroxide-mediated polymerisation (NMP) agents. Here, we describe the synthesis of polystyrene in the presence of the PFN, 1,1,3,3-tetramethyl-2,3-dihydro-2-azaphenalen-2-yloxyl (TMAO) and our attempts to synthesise an improved PFN for NMP based on the azaphenalene substructure.

Diazomethane undergoes a facile 1,3-dipolar cycloaddition with dithiobenzoate RAFT agents and with dithiobenzoate end-groups of polymers formed by reversible addition–fragmentation chain transfer (RAFT) polymerization. Low-molecular-weight poly(methyl methacrylate) with dithiobenzoate end-groups undergoes immediate decolourization and a quantitative doubling of molecular weight.

5′-(2-Phosphoryl-1,4-dioxobutane) (DOB) is a lesion produced in DNA via a variety of damaging agents. The DOB lesion spontaneously generates cis/trans-but-2-en-1,4-dial (1) via β-elimination. cis/trans-but-2-en-1,4-dial forms exocyclic adducts with nucleosides. DOB generates relatively high yields of cis/trans-but-2-en-1,4-dial nucleoside adducts that likely are promutagenic.

Deactivation of mutagenic N-acyloxy-N-alkoxyamides by thiols, which react by an S_N2 process at the anomeric nitrogen.

The readily available N-arylazetidin-2-ones (1) undergo Fries rearrangement at 0–18°C on treatment with triflic acid (see figure). Certain of the resulting 2,3-dihydro-(4H)-quinolones (2) are readily dehydrogenated on exposure to 10% Pd on C and thereby afford the corresponding (4H)-quinolones (3).

Model studies for the preparation of photoaffinity probes designed to explore the nature of gibberellin receptor sites have provided a wide range of gibberellin derivatives that should afford useful scaffolds for incorporating auxiliary groups attached to C-2 and C-12. Compounds were screened for bioactivity in growth and barley endosperm-based bioassays.

A new alkaloid fagraeoside, likely derived from the condensation of secologanin with L-asparagine, was isolated from Fagraea racemosa JACK ex WALL (Loganiaceae) along with secologanoside. Known lignans, flavonoids, iridoid and secoiridoid glucosides were isolated from three other species, namely F. blumei G. Don, F. auriculata Jack, Mal, and F. ceilanica Thunb. The anti-inflammatory, cytotoxic and anti-cholinesterase activity of selected compounds was evaluated.

A series of tetra-n-butylammonium spiroborates derived from diesters of l-tartaric acid have been prepared and their potential as environmentally benign wood protectants investigated. These compounds showed good activity against Coptotermes acinaciformis termites and the spiroborate derived from di-iso-propyl-l-tartrate was surprisingly resistant to leaching from timber.