“…It is interesting to note that there is a single, low-intensity reaction where just this type of carbene extrusion seems to have been observed in a related system, and the products from this reaction have been thoroughly characterized. 52 Neckers and coworkers have studied the photochemistry of the triarylmethyl radical 53 and isolated the products shown in Scheme 18. Thus, the observation of the 9-arylfluorene 54 and the triarylmethane 55 are unexceptional, but the other products, 56, 57, tetraphenylethylene, and benzophenone are precisely the products that one would expect from a carbene extrusion reaction as shown by the mechanism outlined in Scheme 18. It should be mentioned that deuterium labeling studies were conducted using benzene-dg. However, deuterium incorporation was only evaluated for 55.…”