2-(3-Bromopropyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane

This compound is typically obtained as a colorless to pale straw-colored liquid at ambient temperature, characterized by a faint halogenated odor. Its molecular formula is C9H18BBrO2, corresponding to a molecular weight of 248.95. The boiling point is approximately 120–125 °C at reduced pressure (10 mmHg), with a calculated density near 1.16 g/cm³ at 20 °C. It is freely miscible with common organic solvents including dichloromethane, tetrahydrofuran, diethyl ether, and toluene, while exhibiting negligible solubility in water and aliphatic hydrocarbons. The molecule contains a labile primary bromine atom susceptible to nucleophilic displacement, and a pinacol-protected boronate ester that remains stable under anhydrous conditions. Storage in tightly sealed containers under inert atmosphere at reduced temperature (2–8 °C) is recommended to prevent hydrolysis and decomposition. Contact with strong bases, strong nucleophiles, and silver salts should be avoided.

2-(3-Bromopropyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane consists of a threecarbon propyl chain bearing a terminal bromine atom at one end and a pinacol boronate ester at the other. This bifunctional architecture combines an electrophilic alkyl halide with a masked boronic acid within a flexible linear framework. The boronate ester serves as a protected crosscoupling partner, shielding the boron center from premature oxidation while remaining readily activated under palladium catalysis. The primary bromide provides a versatile handle for nucleophilic substitution with amines, alkoxides, thiols, and carbon nucleophiles, enabling introduction of diverse functional groups. The propylene spacer introduces conformational flexibility while maintaining defined separation between the two reactive termini. This combination of orthogonal reactive centers makes the compound an invaluable linchpin for constructing complex molecules through sequential or tandem transformations.

Bifunctional Linker in Organic Synthesis
This bromopropyl boronate ester serves as a versatile linchpin for connecting molecular fragments through sequential functionalization. The bromide can first undergo nucleophilic displacement with amines or alkoxides to introduce polar head groups, followed by Suzuki–Miyaura cross-coupling at the boronate site to append aryl or heteroaryl units. This orthogonal reactivity enables rapid assembly of diverse molecular architectures including pharmaceuticals, agrochemicals, and functional materials.

Pharmaceutical Intermediate
In medicinal chemistry, this compound is employed to introduce boronic acid functionality into drug candidates via the flexible propyl tether. The resulting boron-containing molecules are investigated as proteasome inhibitors for cancer therapy and as β-lactamase inhibitors for combating antibiotic resistance. The bromine handle allows attachment of solubilizing groups or targeting moieties, while the boronate can be unmasked to reveal the active boronic acid for enzyme inhibition.

Materials Science Applications
The bifunctional nature of this molecule makes it valuable for surface functionalization and polymer modification. The bromide can anchor the compound to nucleophilic surfaces such as amines on functionalized silica or polymer backbones, while the boronate ester remains available for further cross-linking or conjugation. These hybrid materials are explored for sensing, catalysis, and drug delivery applications where controlled placement of boron centers is required.

Organic Synthesis Building Block
As a versatile synthetic intermediate, 2-(3-bromopropyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane participates in diverse transformations including nucleophilic substitution with oxygen, nitrogen, and sulfur nucleophiles to generate libraries of functionalized boronate esters. The bromide can be converted to organometallic reagents for cross-coupling, while the boronate engages in Chan–Lam aminations and oxidative Heck reactions. Its utility extends to the synthesis of boron-containing natural product analogs and to methodology development for sequential one-pot reactions.