Photochemical alkylation of ketene dithioacetal S,S-dioxides. An example of captodative olefin functionalization
Radical alkylation of some ketene dithioacetal S,S-dioxides failed through the tin hydride promoted chain process but was successfully performed through stoichiometric photochemical initiation, either by electron transfer or hydrogen abstraction. In the first case, alkyl radicals were produced from tetralkylstannanes (t-Bu-, i-Pr-, n-Bu-SnR(3)) via radical cation fragmentation, while in the second case these were produced from alkanes (cyclohexane, adamantane) by benzophenone triplet. When bulky radicals (t-Bu, adamantyl) were involved, the addition occurred with complete diastereoselectivity.
Gonzalez-Cameno
AM
Dipartimento di Chimica Organica, Universita, V. Taramelli 10, 27100 Pavia, Italy.
Mella
M
Fagnoni
M
Albini
A