I've just heard about a new addition to the superb MayaChemTools.

MayaChemTools is a growing collection of Perl and Python scripts, modules, and classes to support a variety of day-to-day computational discovery needs.

The latest addition RDKitPerformTorsionScan.py

Perform torsion scan for molecules around torsion angles specified using SMILES/SMARTS patterns. A molecule is optionally minimized before performing a torsion scan. A set of initial 3D structures are generated for a molecule by scanning the torsion angle across the specified range and updating the 3D coordinates of the molecule. A conformation ensemble is optionally generated for each 3D structure representing a specific torsion angle. The conformation with the lowest energy is selected to represent the torsion angle. An option is available to skip the generation of the conformation ensemble and simply calculate the energy for the initial 3D structure for a specific torsion angle

The torsions are specified using SMILES or SMARTS patterns. A substructure match is performed to select torsion atoms in a molecule. The SMILES pattern match must correspond to four torsion atoms. The SMARTS patterns containing atom indices may match more than four atoms.