Visible-light-mediated photocatalytic cross-coupling of acetenyl ketones with benzyl trifluoroborate

Abstract

A visible-light-mediated photocatalytic strategy for the radical–radical cross-coupling of acetenyl ketones with benzyl trifluoroborate has been described.

Straightforward Stereoselective Synthesis of Seven-Membered Oxa-Bridged Rings through In Situ Generated Cycloheptenol Derivatives

“…Acetyenic ketones 1 are known compounds, and the spectroscopic data is in agreement with that previously reported: compounds 1a – 1c , 1d , 1e , 1f , 1g , 1h – 1k , 1l , 1m , 1n , 1o , 1p , 1q , 1r , 1s , 1t , and 1u …”

“…In order to explore the source of oxygen, 18 O isotopic labeling experiments were carried out under the standard reaction conditions. When the seven-membered ring M-h was treated with I 2 in the presence of H 2 18 O, 18 O 4 -3h was obtained with a yield of 87%. There are four labeled O atoms in 18 O 4 -3h (Scheme 4a).…”

“…When the seven-membered ring M-h was treated with I 2 in the presence of H 2 18 O, 18 O 4 -3h was obtained with a yield of 87%. There are four labeled O atoms in 18 O 4 -3h (Scheme 4a). These results indicated that two additional oxygen atoms (one from the bridged "O" and the other from the OH group) might come from water.…”

“…These results indicated that two additional oxygen atoms (one from the bridged "O" and the other from the OH group) might come from water. Treatment of 3h under the same reaction conditions, it was found that three 18 O-labeled atoms were incorporated to give 18 O 3 -3h (Scheme 4b). This result suggested that O exchange could take place between H 2 18 O and the three O atoms of the bridged compound 3h (see Scheme 4b, 1 O, 2 O, and 3 O) in the presence of I 2 .…”

Boron, silicon, nitrogen and sulfur-based contemporary precursors for the generation of alkyl radicals by single electron transfer and their synthetic utilization

“…Another opportunity provided by the Ir( ii ) reduction is to generate a ketyl radical anion from ketones 18 that can presumably react through radical coupling with the benzyl radical derived from the organotrifluoroborate 19 leading to coupling adducts 20 (Scheme 5). 23 Of note also, benzyl trifluoroborates can be oxidized to benzaldehydes in flow conditions. 24…”