An efficient cascade transformation toward indolizine-based molecules has been developed. This process leads to the rapid construction of two C-N bonds and one C-C bond without the need of any metal catalysis. The approach involves easily accessible chromone-based Michael acceptors and propargylamine derivatives as starting materials. This cascade constitutes a novel and very competitive alternative to the well reported strategies using pyridine or pyrrole derivatives for accessing the indolizine ring with substituents at uncommon C-positions.

SummaryAmphiphilic compounds are used in a variety of applications due to their lyotropic liquid-crystalline phase formation, however only a limited number of compounds, in a potentially limitless field, are currently in use. A library of organic amphiphilic compounds was synthesised consisting of glucose, galactose, lactose, xylose and mannose head groups and double and triple-chain hydrophobic tails. A modular, high-throughput approach was developed, whereby head and tail components were conjugated using the copper-catalysed azide–alkyne cycloaddition (CuAAC) reaction. The tails were synthesised from two core alkyne-tethered intermediates, which were subsequently functionalised with hydrocarbon chains varying in length and degree of unsaturation and branching, while the five sugar head groups were selected with ranging substitution patterns and anomeric linkages. A library of 80 amphiphiles was subsequently produced, using a 24-vial array, with the majority formed in very good to excellent yields. A preliminary assessment of the liquid-crystalline phase behaviour is also presented.

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An interesting competitive C-C vs. C-O bond coupling reaction on N,3,5-trisubstituted pyridones is reported. These coupling reactions provided selective access to C- or O-ring-fused pyridones, both at the challenging C6-pyridone position. 1,6-C-Annulated pyridones were generally achieved in good yields with excellent chemoselectivity under Pd(0) conditions. On the other hand, full C6-regioselective Csp(2) aryloxylation was achieved under oxidative coupling promoted by silver salts to access 5,6-O-annulated pyridones. Based on various experiments and observations, mechanistic evidence of these competitive reactions was provided and it was proposed that C-O bond formation proceeded through radical cyclization. These processes were performed under mild reaction conditions and offer an efficient and attractive methodology to selectively access a large scope of C-arylated and O-arylated pyridones of biological interest.