[rvalst]

Hi,

I am writing a synthesis proposal to make the compound 4 in the reaction scheme attached.
Notice the stereochemistry; the hydrogen atoms in the middle bond (between the two rings) are
both pointing downward.


I was planning to make 4 via an intramolecular Diels-Alder reaction in compound 3.
I would expect that the hydrogens can end up on either side of the plane; either both pointing upward (undesired),
or both pointing downward (desired), so a mixture of both is obtained.

Would anyone have a suggestion for me on how to ensure the hydrogens are both pointing downward?

[kriggy]

DA reaction is known to be accelerated by various metal salts. Using suitable  metal salt with suitable chiral ligand might get the job done.

This  might give you some information to start with
https://onlinelibrary.wiley.com/doi/10.1002/1521-3773%2820020517%2941%3A10%3C1650%3A%3AAID-ANIE1650%3E3.0.CO%3B2-B

It might however require some further functionalization to work with your substrate but Im sure there is someone here who actually did DA reaction in a lab (unlike me)