A thiyl radical mediated cascade sequence for the co-cyclisation of 1,6-hexadienes with sulfur atom transfer

Thiols, thioethers, and related compounds as sources of C-centred radicals

“…In this reaction, a tert-butyl radical is generated during the intramolecular homolytic substitution and is presumably propagating the chain process (Scheme 24, eqn (a)). 79 Landais and co-workers reported the formation of a tetrahydrothiophene derivative by the closely related cyclization of 3-silahepta-1,6-dienes. As previously observed with these substrates, the presence of the silyl group allows to control the diastereoselectivity of the cyclization process (Scheme 24, eqn (b)).…”

Recent advances in sulfur- and phosphorous-centered radical reactions for the formation of S–C and P–C bonds

“…20c,30d The Harrowven group employed this reaction for the synthesis of substituted thiabicyclo[3.3.0]octanes through a double cyclization process to form C-C and C-S bonds 64. A sulfenyl radical generated by the photolysis of a disulfide could add to diene 49 followed by cyclization through the favorable chair-like transition states to give 50 with the newly formed radical center cis to the sulfide.…”

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“…Harrowven 21 has described a tin-free method of forming a range of fused thiabicyclo[3.3.0]octanes by co-cyclising a 1,6-diene with a tert-butylthio radical and concomitant sulfur atom transfer via an S H 2 reaction at sulfur (Scheme 21). The reaction was much slower if Pyrex was used as the reaction vessel during the irradiation instead of quartz and in such cases the rate of reaction was dramatically increased if triethylborane was added.…”