Still working on the Lewis acid-catalysed Pictet-Spengler reaction

Was quite exhaused this afternoon. I'm having a tiring time wrestling with the KAB26 series, currently aka Yb(OTf)3 catalysed acyl-Pictet-Spengler reactions to give a particular N-acyl tetrahydroisoquinoline.

(SMILES: O=[N+]([O-])C1=CC=C(C2N(C(C)=O)CCC3=CC(OC)=C(OC)C=C32)C=C1).

I'm attempting to optimise the reaction, which has somehow led to running the reactions at -40 to -41C (minimising diacetylated/hydrolysis products). It was quite fun making the acetonitrile/liq. N2 slurry yesterday. Today, I had a difficult time keeping the temperature down - should have changed the bath to one with zero water in it.

Not entirely sure what's going on with the low-ish yield of my reaction. Brain application in progress. Still, I'm quite happy with the H-NMRs of the crude products. I'm now able to quantify product, some hydrolysis by-products and identify pretty much every
And I'm fairly sure the workup of the crude reaction mixture (after thought and numerous attempts) is as good as it's going to get, pending further suggestions....

(incomplete) Lab notes here (they'll be done by tomorrow):

Was also in "writing mode" this evening, attempting to hack away at this atrociously incomplete and out-of-date document ( before promptly re-entering the brain dead mode of a student nearing the end of semester...

#OpenScience #OpenChemistry #Chemistry´╗┐
Adding liquid nitrogen to stuff will never get old (3 photos)
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