At my site, you can find the following descriptions of some of the transformations you mention:
Calamus oil -> Asarone -> Pseudonitrosite -> Nitropropene -> Asarone ketone (https://www.thevespiary.org/rhodium/Rhodium/chemistry/tma2.html)
(https://www.thevespiary.org/rhodium/Rhodium/chemistry/tma2.html)
Calamus oil -> Asarone -> Pseudonitrosite (https://www.thevespiary.org/rhodium/Rhodium/chemistry/asarone.html)
(https://www.thevespiary.org/rhodium/Rhodium/chemistry/asarone.html)
Asarone -> Pseudonitrosite -> Nitropropene (https://www.thevespiary.org/rhodium/Rhodium/chemistry/pseudonitrosite.html)
(https://www.thevespiary.org/rhodium/Rhodium/chemistry/pseudonitrosite.html)
The only part I'm a bit unsure of is the acidic Al/Hg reduction of the oxime, as I don't find that described in my notes on TMA-2 chemistry (but it might be posted somewhere at the Hive, can someone help finding it?). The oxime has been made in good yield using either Sonson's method (https://www.thevespiary.org/rhodium/Rhodium/chemistry/mdaoxime.html)
(https://www.thevespiary.org/rhodium/Rhodium/chemistry/mdaoxime.html) Chromic's modification (https://www.thevespiary.org/rhodium/Rhodium/chemistry/alhg.oxime.html)
(https://www.thevespiary.org/rhodium/Rhodium/chemistry/alhg.oxime.html). The ketoxime is purified according to Post 365007 (https://www.thevespiary.org/talk/index.php?topic=9486.msg36500700#msg36500700)
(Barium: "IPA is a good solvent for asarone ketoxime ...", Methods Discourse)
A more common way is probably reduce the nitropropene to TMA-2, directly or stepwise (https://www.thevespiary.org/rhodium/Rhodium/chemistry/tmp2np-red.html)
(https://www.thevespiary.org/rhodium/Rhodium/chemistry/tmp2np-red.html), as you don't have to proceed through the ketone and ketoxime, which probably gives notably lower yields. In this document there is also a good procedure for the iron reduction of the nitropropene to asarone ketone, if you should decide to use that route in the end.
Anyhow, I suggest that you UTFSE for posts written by Antibody2, Dr_Sister, Chromic and Uemura to find good asarone chemistry discussions. I think that the pros and cons of all the methods you mention has been discussed here at the hive at one time or another during the years.
The pseudonitrosite works well on asarone. make sure you don't use too much H2SO4, or leave it too long or you will end up with red goo/tar and a ring nitrated product if I remember correctly. Little difference has been noted between dripping the acid into the top or bottom layers.
Stepwise reduction of the nitropropene also works well. A good route is reduction of the double bond with borohydride, followed by redution to the amine with Zn/NH4COOH in methanol.
have a look at Post 352269 (https://www.thevespiary.org/talk/index.php?topic=6879.msg35226900#msg35226900)
(Barium: "Wow", Chemistry Discourse)
make sure you don't use too much H2SO4, or leave it too long or you will end up with red goo/tar and a ring nitrated product if I remember correctly.
You remember correctly ;) . Bruckner states that 2,4,5-trimethoxy-nitrobenzene is formed as impurity.
[...] Unterwirft man Asaron [...] in ätherischer oder ligroinischer Lösung der Einwirkung von nitrosen Gasen, so ist keine Ausscheidung eines Additionsproduktes zu bemerken. Auch im Falle sehr energischer Außenkühlung findet nur Oxydation oder Nitrierung statt, die zur Bildung von 2,4,5-trimethoxy-nitrobenzol führt und stets von starker Verharzung begleited wird. Diese merkwürdige Reaktion findet ihre Erklärung in der besonderen Sensibilität des Asarons, die wahrscheinlich mit der Stellung der Methoxylgruppen zur Propenylkette in Zusammenhange steht3.[...]
3. Eine ähnliche Erscheinung trafen beim Nitrierungsversuch der Asaronsäure (2,4,5-trimethoxy-benzoesäure) R Fabinyi und T Széki, Ber Deutsch chem Ges 39 (1906) 3681) an, indem in Eisessiglösung auf Einwirkung van 81 prozent. Salpetersäure die Carboxygruppe abspaltete und ebenfalls 2,4,5-trimethoxy-nitrobenzol entstand.
Bruckner also finds the nitrated impurity when he prepared the pseudonitrosite the traditional way. As Fabinyi and Széki found that 2,4,5-trimethoxybenzoic acid is converted to the same 2,4,5-trimethoxy-nitrobenzene when treated with HNO3, my guess is that asarone is partially oxidized to 2,4,5-trimethoxybenzoic acid (as a side reaction; atmospheric oxygen and an acidic environment can cause this cleavage), which in turn is nitrated.
For those interested in chemical history: Fabinyi and Széki have done quite some research in the asarone-field; for instance Post 431532 (https://www.thevespiary.org/talk/index.php?topic=6823.msg43153200#msg43153200)
(GC_MS: "Characterization of asaraldehyde", Chemistry Discourse).
Reference of the Bruckner text: V Bruckner. Über das Pseudonitrosit des Asarons. J prakt Chem 138 (1933) 268-274. Also found on Rh's site.