Python API

find_routes

renkin.find_routes(
    smiles: str,
    depth: int = 5,
    max_routes: int = 5,
    beam_width: int = 0,
    building_blocks: list[str] | None = None,
) -> dict

Find retrosynthetic routes for a target molecule.

Parameters:

Parameter	Type	Default	Description
smiles	str	required	Target molecule as SMILES string
depth	int	5	Maximum number of retrosynthetic steps
max_routes	int	5	Maximum number of routes to return
beam_width	int	0	A* beam width (0 = unlimited BFS/A*)
building_blocks	list[str]	None	Custom building block SMILES list. If None, uses the built-in library (509 compounds)

Returns:

{
    "routes_found": int,   # number of routes found
    "routes": [
        {
            "depth": int,   # number of steps in this route
            "steps": [
                {
                    "target": str,           # SMILES of molecule being disconnected
                    "rule": str,             # reaction rule name
                    "precursors": list[str], # SMILES of precursor molecules
                }
            ]
        }
    ]
}

Example:

import renkin

result = renkin.find_routes("CC(=O)Oc1ccccc1C(=O)O", depth=5, max_routes=3)

print(f"Routes: {result['routes_found']}")
for route in result['routes']:
    print(f"  depth={route['depth']}: {len(route['steps'])} step(s)")

version

renkin.version() -> str

Returns the RENKIN version string.

>>> import renkin
>>> renkin.version()
'0.2.1'

Building Blocks

The default building block library includes 509 commercially available compounds:

• Simple aliphatics (C1–C6 chains, alcohols, acids)
• Aryl and heteroaryl halides (Br, Cl, I)
• Boronic acids (Suzuki coupling acceptors)
• Pyridines, pyrimidines, pyrazoles, imidazoles, furans, thiophenes
• Common pharmaceutical amines (piperidine, morpholine, piperazine, etc.)
• Aldehydes and ketones for reductive amination
• Protecting group reagents (Boc, Cbz)
• Amino acids (Gly, Ala, Asp, Glu, Ser, Phe, Tyr, Lys, Cys, Val)

To use a custom library, pass a list of SMILES strings to the building_blocks parameter.

Error Handling

import renkin

try:
    result = renkin.find_routes("invalid_smiles")
except Exception as e:
    print(f"Error: {e}")
    # "Failed to parse SMILES: invalid_smiles"

Common errors: - Failed to parse SMILES: ... — invalid SMILES string - Building block parse error: ... — invalid SMILES in custom building blocks list