Low temperature free-radical reactions initiated with tert-butyl p-benzoylperbenzoate. Selective acyl radical additions to substituted olefins

Chemistry of Acyl Radicals

“…309 The resulting radical 303 experiences a 6-exo cyclization to form a sixmembered ring adduct 304 as a 43:57 mixture of diastereomers. The diastereoselectivity of this reaction was found to be rather insensitive to the reaction temperature in the range from -25 to 78°C (41:59 to 44:56).…”

“…Gottschalk and Neckers investigated competition experiments involving acyl radical additions to simple and electron-deficient alkenes by changing the reaction temperature. They employed tert -butyl p -benzoylperbenzoate ( 210 ) as the photoinitiator (Scheme ) …”

“…Neckers reported that radical addition of acetaldehyde to methyl octa-2,7-dienoate ( 302 ) at 4 °C occurs at the inner rather than terminal alkene chemoselectively (Scheme ) . The resulting radical 303 experiences a 6-exo cyclization to form a six-membered ring adduct 304 as a 43:57 mixture of diastereomers.…”

Ultrasonographic findings in conservatively treated placenta percreta

“…However, lowering the temperature is not an option thermally because it slowed down the rate of the chain reaction. In the present case, the photocatalyzed hydrogen‐abstraction step was virtually independent of the temperature and application to easily fragmenting acyl radicals at a low temperature seemed possible 20…”

CHAPTER 1. The Evolution of the Concept of Cross-Dehydrogenative-Coupling Reactions

“…Based on the studies of Gottschalk and Neckers in 1985, 85 the group of Lei developed a radical Cu-catalyzed cross-dehydrogenative olefination reaction that gives direct access to a,b-unsaturated ketones (Scheme 1.45). 86 Various aromatic and heteroaromatic aldehydes were coupled with styrenes in the presence of catalytic quantities of CuCl 2 and TBHP at 80 1C.…”