Thank you Rohan, hope you find it useful. James

The Diels-Alder will *always* make a new six-membered ring, but depending on your starting materials, other size rings might get made in the process
if you count around the perimeter.

One case is when you do an intramolecular diels alder reaction, where a ring larger than 6 will be created in addition to the new 6 membered ring. https://www.masterorganicchemistry.com/2019/12/06/the-intramolecular-diels-alder-reaction/

A Diels Alder between a cyclic diene and a cyclic dienophile will likewise form a new 6-membered ring, but if you count *all* the atoms around the perimeter (i.e. around the perimeter of both rings) then yes, you will have a cyclic structure of greater than 6. If you count around the ring in decalin (the structure formed by fusing 2 6-membered rings) you get 10 carbons; I’d personally call this a “bicycle” or bicylic structure, not a 10-membered ring, personally, but hopefully you get the idea

Glad you found it helpful!

The methoxy would end up on the same side of the new six membered ring as the hydrogen on the “outside” position. If both the diene and dienophile have substituents, then you’ll likely form endo and exo diastereomers. See https://www.masterorganicchemistry.com/2018/02/09/endo-exo-diels-alder-telling-them-apart/