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Also called "banana borane", it exists as a dimer. It can be distilled without decomposition at 195 °C (12mm Hg). Reactions with 9-BBN typically occur at 60–80 °C, with most alkenes reacting within one hour. Tetrasubstituted alkenes add 9-BBN at elevated temperature. Hydroboration of alkenes with 9-BBN proceeds with excellent regioselectivity.
Almost identical to that of Wacker Process, the proposed catalytic cycle [32] (Figure 1) begins with complexation of PdCl 2 and two chloride anions to PdCl 4, which then undergoes subsequent ligand exchange of two chloride ligand for water and alkene to form Pd(Cl 2)(H 2 O)(alkene) complex.
Hydroboration of 1,2-disubstituted alkenes, such as a cis or trans olefin, produces generally a mixture of the two organoboranes of comparable amounts, even if the steric properties of the substituents are very different. For such 1,2-disubstituted olefins, regioselectivity can be observed only when one of the two substituents is a phenyl ring.
It adds across alkenes to give organoboron compounds that are useful intermediates. [4] The following organoboron reagents are prepared from borane-THF: 9-borabicyclo[3.3.1]nonane, Alpine borane, diisopinocampheylborane. It is also used as a source of borane (BH 3) for the formation of adducts. [5]
The B-B bond adds across alkenes and alkynes to give the 1,2-diborylated alkanes and alkenes. Using various organorhodium or organoiridium catalysts, it can also be installed onto saturated hydrocarbons: [3] CH 3 (CH 2) 6 CH 3 + [pinB] 2 → pinBH + CH 3 (CH 2) 7 Bpin. These reactions proceed via boryl complexes. Bis(pinacolato)diboron can also ...
One attractive feature of the Peterson olefination is that it can be used to prepare either cis- or trans-alkenes from the same β-hydroxysilane. Treatment of the β-hydroxysilane with acid will yield one alkene, while treatment of the same β-hydroxysilane with base will yield the alkene of opposite stereochemistry.
Alkenes react with percarboxylic acids and even hydrogen peroxide to yield epoxides: RCH=CH 2 + RCO 3 H → RCHOCH 2 + RCO 2 H. For ethylene, the epoxidation is conducted on a very large scale industrially using oxygen in the presence of silver-based catalysts: C 2 H 4 + 1/ 2 O 2 → C 2 H 4 O. Alkenes react with ozone, leading to the scission ...
Wilkinson's catalyst also catalyzes many other hydrofunctionalization reactions including hydroacylation, hydroboration, and hydrosilylation of alkenes. [14] Hydroborations have been studied with catecholborane and pinacolborane. [15] It is also active for the hydrosilylation of alkenes. [16]