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S-(1-Oxido-2-pyridinyl)-1,1,3,3-tetramethylthiouronium hexafluorophosphate (HOTT) facilitates the first examples of efficient radical cyclisation with (hetero)aromatic substitution via Barton ester intermediates. Cyclopropyl and alkyl radicals allow access to five, six and seven-membered alicyclic-ring fused heterocycles with and without an additional fused cyclopropane, including the skeleton of the anti-cancer agent, cyclopropamitosene, expanded, and diazole analogues. Radical initiators are not required for cyclisation from carboxylic acid precursors.

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A one-pot initiator-free Barton ester decomposition with tandem radical addition onto alkyl propiolates or phenylacetylene with aromatic substitution of the resultant vinyl radical allows convenient access to new 9-substituted 6,7dihydropyrido[1,2-a]indoles. Propyl radical cyclizations compete when forming the expanded 7,8-dihydro-6H-azepino[1,2a]indole system. 2-Thiopyridinyl S-radical is incorporated into aromatic adducts when using unsubstituted indole-1-alkanoic acid precursors. X-ray crystallography on substitution products allows selectivity of the radical addition onto less reactive internal alkynes to be determined.

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This practical is aimed at students who have been introduced to the tableting process, drug delivery systems, and dissolution. The student can design and manufacture a tablet investigating the effect of excipients and their role in tablet design and then generate a release profile of the tablet by using a dissolution apparatus, flow-through cell, and UV–vis kinetics. Economical alternatives to the otherwise expensive dies, presses, and dissolution apparatus required to conduct the practical are included so that this can be applied across a range of budgets. With the assumption that most undergraduate laboratories possess a 13 mm KBr die and hydraulic press, a 10 mm die and 6 mm die can cost in excess of €850, while homemade versions can be manufactured for less than €5.

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