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A pinacol coupling reaction is an organic reaction in which a carbon–carbon bond is formed between the carbonyl groups of an aldehyde or a ketone in presence of an electron donor in a free radical process. [1] The reaction product is a vicinal diol. The reaction is named after pinacol (also known as 2,3-dimethyl-2,3-butanediol or ...
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 ...
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 pinacol–pinacolone rearrangement is a method for converting a 1,2-diol to a carbonyl compound in organic chemistry. The 1,2-rearrangement takes place under acidic conditions. The name of the rearrangement reaction comes from the rearrangement of pinacol to pinacolone. [1]
A common migration introduction of carbon is a pinacol rearrangement. [1] While this reaction refers specifically to a vicinal dihydroxide rearrangement, there are other pinacol type rearrangements that proceed through the same general mechanism such as the Tiffeneau–Demjanov rearrangement .
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.
A third method is by palladium catalysed reaction of aryl halides and triflates with diboronyl esters in a coupling reaction known as the Miyaura borylation reaction. An alternative to esters in this method is the use of diboronic acid or tetrahydroxydiboron ([B(OH 2)] 2). [14] [15] [16]
Most famously, at least in the classroom, pinacolone arises by the pinacol rearrangement, which occurs by protonation of pinacol (2,3-dimethylbutane-2,3-diol). [4] Industrially pinacolone is made by the hydrolysis of 4,4,5-trimethyl-1,3-dioxane, which is the product of isoprene and formaldehyde via the Prins reaction.