A primary alkyl steric protection group bearing a cavity-shaped framework, a BpqCH(2) group, was developed. A sulfenyl iodide with the BpqCH(2) group was successfully synthesized and unambiguously characterized by X-ray crystallographic analysis. The sulfenyl iodide showed remarkable stability both in the solid state and in solution, demonstrating that the BpqCH(2) group is promising for kinetic stabilization of primary alkyl substituted reactive species.