stumbled upon an answer to my own question, so thought I would post it for completeness:
"yes, the best yeilds 60%, were reported with P2NP, followed by TMP2NP at 55%, p-MP2NP at 25% and both MDP2NP and DMMDP2NP failed altogather with acidic activations. in most cases at least two rxns, in some like MDP2NP several times with a whole spectrum of variations."
can be found in a comment by Dr_Sister in the following document:
https://www.thevespiary.org/rhodium/Rhodium/chemistry/urushibara.txt (https://www.thevespiary.org/rhodium/Rhodium/chemistry/urushibara.txt)