Efficient synthesis and unit-selective -extension of -fused [4.3.3]propellane as a chiral building block

A three-dimensional skeleton, pi-fused [4.3.3]propellane, was constructed and derivatized by selective pi-extension at the two naphthalene units. The obtained propellanes existed as stereoisomers different in spatial arrangement, one of which displayed a chiroptical response originating from through-space interactions between 5-azachrysenes in a skew position.