How sensitive is Cu-free Sonogashira to moisture and/or oxygen?

Hello all,

I'm trying to run a Sonogashira that is a direct copy of a literature reaction - same substrates, catalysts, conditions, etc:

Aryl chloride (1 eq), XPhos Pd G3 (0.2 equiv), XPhos Ligand (0.2 equiv), propargylamine (3 equiv), and Cs2CO3 (3 equiv), dry MeCN (10 mL), microwave at 90C for 60 mins followed by purification.

All of my reagents were brand new and fresh, and I opened the bottles just for this reaction. The reaction ended up failing - I recovered a small bit of starting material (aryl chloride) and some minor unidentifiable byproducts.

My best guess as to what happened is that my microwave vial caps are not a great seal and oxygen got into the reaction and killed the reaction? The caps are soft plastic and do not provide a tight seal. However, I've read online that Cu-free Sonogashiras are less sensitive to presence of oxygen. Any suggestions as to what went wrong? My next move is to order some new microwave caps that provide a tight air free seal.

Thanks

Edit: Looks like the competing Buchwald-Hartwig amination was the issue, as a switch to N-boc propargylamine allowed success. In fact, these conditions are almost identical to certain BH amination conditions, so it's a surprise the literature reported a successful Sonogashira with 90% yield....

See here for similar BH amination conditions: https://pubs.acs.org/doi/pdf/10.1021/acs.organomet.1c00517