What rigid architectural feature defines a classic "Spirane" system within the context of organic re — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

Spiranes (or spiro compounds) are chemically defined as bicyclic structures where the two constituent cycloalkane rings are tightly fused by sharing a single common central carbon atom (the spiro carbon). Geometrically, this forces the planes of the two fused rings to be mutually perpendicular to one another, precisely mirroring the orbital mechanics seen in an allene pi-system.