Andrew Plant

Current Challenges and Trends in the Discovery of Agrochemicals

Crop protection chemistry has come a long way from its “alchemic” beginnings in the late 19th century to a high-tech science that supports the sustainable production of food, feed, and fiber for a rapidly growing population. Cutting-edge developments in the design and synthesis of agrochemicals help to tackle today’s challenges of weed and pest resistance, higher regulatory safety margins, and higher cost of goods with the invention of selective, environmentally benign, low use rate, and cost-effective active ingredients.

Investigation of the Scope and Regiochemistry of Alkynylboronate Cycloadditions with Sydnones

The cycloaddition of alkynylboronates and sydnones provides a convenient and highly regioselective method for the synthesis of a broad range of di-, tri-, and tetrasubstituted pyrazole boronic esters. The origins of an observed regiochemical divergence in the reactions of terminal alkynylboronates with their more substituted analogues have been studied by DFT methods.

Iron(II) triflate as an efficient catalyst for the imination of sulfoxides.

The challenging imination of benzyl-, sterically demanding alkyl-, and heteroaryl-substituted sulfoxides has been studied. Iron(II) triflate was identified as a highly efficient and robust catalyst for sulfur imination reactions. A variety of sulfoxides and sulfides were efficiently iminated with sulfonyliminoiodinanes (PhI=NSO(2)R) at room temperature to give the corresponding sulfoximines and sulfilimines in good yields and with short reaction times.

Alkyne [3 + 2] Cycloadditions of Iodosydnones Toward Functionalized 1,3,5-Trisubstituted Pyrazoles

The cycloaddition of 4-iodosydnones with terminal alkynes proceeds with excellent regiocontrol to provide 5-iodo pyrazoles. These products participate smoothly in subsequent C-C and C-heteroatom bond forming processes.

A novel approach to functionalised pyridazinone arrays

A series of 3,6-dichloro-1H-pyridazin-4-ones have been prepared via the cycloaddition of 3,6-dichlorotetrazine with alkynylboronates, and their employment as useful synthetic intermediates was highlighted through a selection of highly regioselective C-O, C-S and C-C bond forming reactions.

Cross coupling of bromo sydnones: development of a flexible route toward functionalized pyrazoles.

The application of a Suzuki cross coupling approach to a range of C-4 substituted sydnones from a 4-bromosydnone is described. Moreover, the potential of this approach to prepare a diverse range of pyrazoles is demonstrated.

An Improved Process for the Preparation of an α,α-Difluorosulfonylisoxazoline Herbicide.

An efficient synthesis of a difluorosulfone-containing herbicide has been achieved by selective reductive silylation of a symmetrical bis(trifluoromethyl)-1,2,3-triazole. Subsequently, a fluoride-induced reaction led to a difluoromethyl anion equivalent, which was reacted with a sulfur electrophile leading ultimately to the key difluorosulfide moiety.