at 40C (104F) maybe not, but I shave started seeds in full sun many times and had them grow great from germination on. At those temps it isn't the sun that is the issue though, it is the heat itself.
However if I did not start them in full sun and moved them to full sun they would die in hours if small and be severely burned and permanently scarred if they were older.
I have also seen them survive very hot bright conditions, but they stall in heat (mine always stopped growing when the temp climbed in summer and mostly grew in fall and spring, these plants do not like excessive heat, one of the best climates for them is the Bay Area in CA.
[URL unfurl="true"]http://www.weather.com/weather/wxclimatology/monthly/graph/USCA0987[/URL]
Another is Florida though they like nights slightly cooler than are often found there:
[URL unfurl="true"]http://www.southfloridavacation.com/weather.html[/URL]
In such environments they can and will thrive with full sun, once acclimated to it.
If I had climate controls I would raise them with daytime temps from 70-80 F (20-26C) and nighttime temps from 50-60 F (10-15C).