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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.
They reported the reaction of phenylboronic acid in water (140-150 °C) to afford the protodeboronated product, benzene, after 40 hours. Initial synthetic applications of protodeboronation were found alongside the discovery of the hydroboration reaction, in which sequential hydroboration-protodeboronation reactions were used to convert alkynes ...
The general structure of a boronic acid, where R is a substituent.. A boronic acid is an organic compound related to boric acid (B(OH) 3) in which one of the three hydroxyl groups (−OH) is replaced by an alkyl or aryl group (represented by R in the general formula R−B(OH) 2). [1]
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 .
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.
As shown in Scheme 1, the ring synthesis of ring C began with a Diels-Alder reaction between diene 1.3 and dienophile 1.1 in the presence of phenylboronic acid (1.2), which, after addition of 2,2-dimethyl-1,3-propanediol, gave five-membered lactone 1.8 in 62% yield.
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.
The first synthesis of 1,3-diphenylisobenzofuran was reported in 1905 by A. Guyot and J. Catel. [9] [10] Phenylmagnesium bromide was reacted with 3-phenylphthalide (the latter accessible from the methyl ester of 3-hydroxyphthalide with phenylboronic acid in 95% yield [11]) to a lactol, which gives with mineral acids upon elimination of water 1,3-diphenylisobenzofuran with 87% yield.