Lewis acid mediated intramolecular Mannich reaction between an azocinone and a 3-formylindole was investigated as part of a study towards the synthesis of actinophyllic acid. The intramolecular Mannich reaction resulted in a single diastereomer of the 1-azabicyclo[4.2.1]nonan-5-one core framework, although single crystal X-ray structure analysis revealed that this had the undesired stereochemistry in comparison with the natural product.Figure optionsDownload full-size imageDownload as PowerPoint slide

The synthesis of azine-substituted pyrazoles by a sydnone cycloaddition strategy is described. Incorporation of a 3-pyridyl moiety at the sydnone N-atom has little effect on either reactivity or regioselectivity, however, 2-ethynyl-pyridine and -pyrimidine undergo cycloaddition with surprisingly poor levels of regiocontrol. A rationale for the observed regiochemical trends and potential routes for improving selectivities are discussed.

A mild method for the generation of benzynes from 2-(trimethylsilyl)iodobenzene derivatives is reported. The employment of silver fluoride in conjunction with caesium fluoride is key for promoting useful levels of elimination and providing benzyne derived products in good yields. Moreover, the substrates are accessed by a novel alkynyl iodide cycloaddition.

A concise synthesis of three members of the withasomnine family of natural products is reported. The synthesis features a regioselective sydnone–alkynylboronate cycloaddition followed by Suzuki cross coupling and silyl group removal, and marks the first divergent approach to this family of pyrazole based natural products.

A concise synthesis of three members of the withasomnine family of natural products is reported. The synthesis features a regioselective sydnone–alkynylboronate cycloaddition followed by Suzuki cross coupling and silyl group removal, and marks the first divergent approach to this family of pyrazole based natural products.