I say difficult because it appears we are going to require nitriles.
That may not be so tough, though - Saturn's moon Titan does it with a hundredth of the UV light we have:
The Process of Tholin Formation in Titan's Upper AtmosphereJ. H. Waite, Jr.,
et al., Science 11 May 2007: 870-875.
In this paper, we report on quantitative observations of hydrocarbon-nitrile compounds in Titan's upper atmosphere (950 to 1150 km) by the INMS, together with evidence from the Cassini Plasma Spectrometer (CAPS) of heavy positively charged (100 to 350 daltons) and negatively charged (20 to 8000 daltons) ions. The presence of negative ions in particular was a complete surprise, and we argue that they play an important role in tholin formation. These data were obtained during six recent Titan encounters (Tables 1 and 2), indicating that the chemical processes are a persistent phenomenon.
Titan's atmosphere is largely nitrogen and methane - and we likely had significant methane "back when."