What is the “spiro” piece in rolapitant patent synthesis?
Rolapitant is an NK1 receptor antagonist. When patents describe “spiro” intermediates in a synthesis route, they’re referring to a specific spirocyclic carbon framework (a ring system where two rings share a single atom). That spiro motif typically appears as an intermediate or a protected/functionalized building block that later gets converted into rolapitant’s final scaffold via coupling, substitution, or functional-group interconversion steps.
Because your query is short (“Us patent rolapitant synthesis spiro”) and does not name a patent number or the exact “spiro” term used in the claim/spec, I can’t reliably identify which exact US patent document you mean or which spiro intermediate is referenced.
Which US patent should I look at to find the rolapitant spiro synthesis steps?
To pinpoint the exact synthesis language, you’ll need one of these:
- the US patent number (e.g., US 20XX/XXXXX)
- the assignee/company name (often the applicant)
- the exact keyword used alongside “spiro” (for example “spiro[... ]”, “spirocyclic”, or the spiro-ring system size)
- the intermediate name from the example section
If you share any of the above, I can extract the relevant synthesis steps and map how the spiro intermediate is transformed into rolapitant.
Why do patents use spiro intermediates in rolapitant routes?
Patents often employ spirocyclic intermediates because they:
- create or lock a 3D geometry used to match the target’s binding requirements
- provide a stable scaffold for selective functionalization on a specific ring position
- simplify later transformations by keeping certain groups protected or positioned for coupling/substitution
The exact reason in a specific patent depends on the spiro structure and the transformations described in the example.
What do “synthesis” sections in rolapitant US patents usually include?
In US patent examples, the “synthesis” around a spiro intermediate commonly includes:
- preparation of the spiro ring (or procurement and functionalization)
- protection/deprotection steps (if needed)
- formation of the key bond(s) leading toward the final rolapitant skeleton
- purification details (typical solvents/recrystallization or chromatography)
- characterization (NMR, MS, etc.)
The spiro part usually appears in the step where the framework is installed or where a spiro-functionalized intermediate is converted into the next coupling partner.
If you meant a specific structure: what should you paste from the patent?
If you paste the relevant snippet (the example text or the chemical name containing “spiro”), I can:
- interpret the spiro structure (ring system and shared atom)
- explain which step is doing the ring formation vs. which step is doing functional-group conversion
- translate the patent’s “Example” procedure into a clearer, stepwise reaction description
Quick check: are you looking for “rolapitant” or “spiro[rolapitant]”?
Sometimes search queries like yours combine terms from different contexts (e.g., rolapitant plus an unrelated “spiro” scaffold from a different compound class, or a spiro intermediate used for a different NK1 antagonist). Confirming the patent number or the spiro ring name prevents mixing routes.
Send me one detail and I’ll narrow it precisely
Reply with either:
1) the US patent number/link, or
2) the exact “spiro” chemical name/ring notation from the patent, or
3) the applicant/assignee name.
Then I can summarize the exact US-patent rolapitant synthesis route around that spiro intermediate.