ИСТИНА

Alkynes and alkenes are widely used substrates in organic synthesis due to their excess energy, concealed in multiple bonds. Coupling of alkynes with other alkynes or alkenes with specific selectivity is a challenging task, which can be overcame by transition metal catalysis. However, this approach requires usage of substrates with directing groups, which can not be easily removed after the synthesis. This problem also has not been solved yet by radical reactions. In this study novel metal-free photocatalytic approach to the yne-ene coupling is considered. Products 4 are obtained with yields up to 81% [1, 2]. Thiol-yne-ene reaction can be carried out with preliminary one-pot photocatalytic synthesis of α-vinilylsulfide 3 from alkyne and thiol [3]. Ease of elimination of thiol, implemented on the first step allows consider this sequence as a thiol-yne-yne coupling strategy with obtaining of activated diene 6. Proposal of the mechanism of thiol-yne-ene reaction is made on the basis of investigation of intermediates by combination of EPR, UHRMS and NMR experiments.