2,2',3,3'-Tetrahydro-1,1'-spirobi[1H-indene]-7,7'-diol
[CAS 223137-87-9]

Identification

• Classification: Chemical reagent >> Chiral chemical reagent
• Name: 2,2',3,3'-Tetrahydro-1,1'-spirobi[1H-indene]-7,7'-diol
• Synonyms: 3,3'-spirobi[1,2-dihydroindene]-4,4'-diol
• Molecular Formula: C₁₇H₁₆O₂
• Molecular Weight: 252.31
• CAS Registry Number: 223137-87-9
• SMILES: C1CC2(CCC3=C2C(=CC=C3)O)C4=C1C=CC=C4O

Properties

• Density: 1.34

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H302-H315-H319-H332-H335
• Safety Statements: P261-P280-P305+P351+P338

chemBlink Chemical Story

Some molecules are valuable because their shape can organize the chemistry taking place around them. SPINOL, the common abbreviation for 1,1'-spirobiindane-7,7'-diol, is an example. Its two indane units share a single spiro carbon, while two phenolic hydroxyl groups provide sites for chemical modification. The structure is a compact platform for constructing more elaborate ligands and catalysts.

The entry CAS 223137-87-9 names the framework without an R or S descriptor. It should be distinguished from entries that explicitly identify a single enantiomer. The spiro arrangement allows handedness even though a casual reading of the name might suggest only two similar rings and two hydroxyl groups. A racemic sample contains both mirror-image forms; a name without a stereochemical descriptor does not certify the enantiomeric composition of an individual batch.

Birman, Rheingold, and Lam reported this chiral diol in 1999. Their paper described preparation of the framework and resolution through derivatives made with a chiral menthyl-derived group. The historical significance was more than the preparation of another diol. It introduced a rigid, C2-symmetric architecture that could be taken forward into asymmetric synthesis.

Resolution addresses a different problem from ordinary purification. Removing unrelated impurities improves chemical purity, whereas separating enantiomers changes the balance between two compounds with the same connectivity and opposite handedness. A material can be chemically pure yet racemic. This distinction is central to understanding why a general SPINOL entry and an enantiomer-specific entry serve different research needs.

Later work demonstrated the framework's adaptability. A 2010 study converted the S enantiomer into chiral phosphoric acid catalysts and used those derivatives in an asymmetric carbon-carbon bond-forming reaction. That application belongs to modified, stereochemically defined catalysts. It should not be read as proof that an unspecified sample of the free diol will reproduce the same selectivity.

SPINOL's story connects scaffold preparation, stereochemical separation, and catalyst design. The two hydroxyl groups are useful starting points, but the spatial organization of the underlying framework is equally consequential. For researchers, specifying which form is present is therefore part of the chemistry itself: connectivity describes what is joined together, while stereochemistry describes how that arrangement can influence a reaction in three-dimensional space.

References:
1. Sigma-Aldrich / Ambeed. 2,2',3,3'-Tetrahydro-1,1'-spirobi[indene]-7,7'-diol, CAS 223137-87-9. https://www.sigmaaldrich.com/US/en/product/ambeedinc/ambh2d6f188e
2. Birman VB, Rheingold AL, Lam KC. 1,1'-Spirobiindane-7,7'-diol: a novel, C2-symmetric chiral ligand. Tetrahedron: Asymmetry. 1999;10:125-131. https://doi.org/10.1016/S0957-4166(98)00481-9
3. SPINOL-Derived Phosphoric Acids: Synthesis and Application in Enantioselective Friedel-Crafts Reaction of Indoles with Imines. J Org Chem. 2010;75:8677-8680. https://doi.org/10.1021/jo101640z

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