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Examples of boronic esters Boronic ester Diol Structural formula Molar mass CAS number Boiling point (°C) Allylboronic acid pinacol ester: pinacol: 168.04: 72824-04-5: 50–53 (5 mmHg) Phenyl boronic acid trimethylene glycol ester: trimethylene glycol: 161.99: 4406-77-3: 106 (2 mm Hg) Diisopropoxymethylborane: isopropanol: 144.02 86595-27-9: ...
It has the formula [(CH 3) 4 C 2 O 2 B] 2; the pinacol groups are sometimes abbreviated as "pin", so the structure is sometimes represented as B 2 pin 2. It is a colourless solid that is soluble in organic solvents. It is a commercially available reagent for making pinacol boronic esters for organic synthesis.
Boronic acids and esters are classified depending on the type of carbon group (R) directly bonded to boron, for example alkyl-, alkenyl-, alkynyl-, and aryl-boronic esters. The most common type of starting materials that incorporate boronic esters into organic compounds for transition metal catalyzed borylation reactions have the general ...
Phenylboronic acid or benzeneboronic acid, abbreviated as PhB(OH) 2 where Ph is the phenyl group C 6 H 5 - and B(OH) 2 is a boronic acid containing a phenyl substituent and two hydroxyl groups attached to boron. Phenylboronic acid is a white powder and is commonly used in organic synthesis.
Pinacol is a branched alcohol which finds use in organic syntheses. It is a diol that has hydroxyl groups on vicinal carbon atoms. A white solid that melts just above room temperature, pinacol is notable for undergoing the pinacol rearrangement in the presence of acid and for being the namesake of the pinacol coupling reaction .
The Miyaura borylation has shown to work for: Alkyl halides, [2] aryl halides, [1] [3] [4] aryl halides using tetrahydroxydiboron, [5] aryl halides using bis-boronic acid, [6] aryl triflates, [7] aryl mesylates, [8] vinyl halides, [9] vinyl halides of α,β-unsaturated carbonyl compounds, [10] and vinyl triflates.
Hydrolysis then results in the boronic acid (R 2 BOH). [5] Trialkylborates [(RO) 3 B] or trialkoxyboroxine [(ROBO) 3] can be reduced to borinic acid by us of a Grignard reagent. Grignard reagents can also reduce a boronic ester [RB(OR') 2] to a borinic ester. [5] Bu 3 B + N2CHCOR → BuCH=C(R)OBBu 2 Bu 3 B + CH2=CHCOCH 3 → BuCH 2 CH=C(CH 3)OBBu 2
The reaction is named after pinacol (also known as 2,3-dimethyl-2,3-butanediol or tetramethylethylene glycol), which is the product of this reaction when done with acetone as reagent. The reaction is usually a homocoupling but intramolecular cross-coupling reactions are also possible. Pinacol was discovered by Wilhelm Rudolph Fittig in 1859.