I don’t have enough information from the prompt to identify the specific “cyclopropyl isocyanate” lenvatinib synthesis patent you mean (for example, the patent number, assignee, or publication country), so I can’t reliably state claims, filing/priority dates, or whether it covers a specific intermediate.
What patent is it (and how to find the right one)?
Search the patent databases using combinations of:
- “lenvatinib” AND “cyclopropyl isocyanate”
- “cyclopropyl isocyanate” AND “lenvatinib synthesis”
- “isocyanate” AND “cyclopropyl” AND “lenvatinib”
Then filter for patent documents (not articles) and check the assignee/company and the “intermediates” sections or examples where isocyanates are prepared/used.
If you share any one of the following, I can narrow it down precisely and summarize what the patent covers:
- patent publication number (e.g., WO/US/EP + number)
- assignee/company name
- a link or screenshot of the patent text where “cyclopropyl isocyanate” appears
- the specific intermediate name used in the example (sometimes the document uses a code name rather than the plain chemical name)
Does the patent cover making the cyclopropyl isocyanate itself or using it in lenvatinib?
Patents on syntheses often split into different types of coverage:
- Methods for preparing an intermediate (process claims)
- Intermediates themselves (compound claims)
- Methods for producing lenvatinib using that intermediate (use in final/advanced-step claims)
The “cyclopropyl isocyanate” phrase might appear as:
- a reagent purchased as starting material, or
- an intermediate prepared in a step described in the examples, or
- a key step in converting an amine to the corresponding urea/carbamoyl linkage in the lenvatinib route.
Which of these it is determines what claim scope you’re actually asking about.
How long would such a patent last (basic timing)?
If you find the exact publication, the typical expiration logic depends on the jurisdiction and whether it’s a patent term with possible extensions:
- Standard patent term is often 20 years from the earliest priority date, subject to adjustments/extension rules.
- Longer effective life can happen via supplementary protection mechanisms in some regions (e.g., Europe), but only if eligibility is met.
What to check in the claims (to see if it really covers the synthesis step)?
Once you identify the correct document, check:
- Whether claims mention “cyclopropyl isocyanate” by name, or a generic definition (e.g., “cycloalkyl isocyanate”)
- Whether claims describe the isocyanate preparation step (carbonylation/phosgenation routes, etc.) or only its use downstream
- Whether it’s limited to particular conditions, catalysts, temperatures, or solvents (which can narrow infringement risk)
- Whether there are multiple examples showing fallback routes
If you meant a competitor’s freedom-to-operate angle
People sometimes search this way because a synthesis patent can affect:
- contract manufacturing of lenvatinib intermediates,
- sourcing the intermediate (supplier patent constraints), or
- process changes that avoid the specific intermediate/reagent step.
To answer that angle, you’d need the exact patent(s) and the relevant geography.
Next step
Send the patent publication number (or paste the claim text/snippet where “cyclopropyl isocyanate” appears). Then I can:
- identify the patent family,
- summarize what it claims about cyclopropyl isocyanate in the lenvatinib synthesis,
- and explain how/when it would typically expire based on its priority dates.
Sources
No sources were used because no specific patent document (number/link) was provided.