Cascade Claisen and Meinwald Rearrangement for One-Pot Divergent Synthesis of Benzofurans and 2 H-Chromenes
A new cascade approach has been developed for the one-pot four-step divergent synthesis of polysubstituted benzofurans and 2H-chromenes, featuring a novel cascade aromatic Claisen rearrangement/Meinwald rearrangement/dehydrative or oxidative cyclization. This new method was demonstrated with 39 examples tolerating different substitutions at an epoxide, allylic ether, and aromatic ring, and we showcased its utility with the first total synthesis of natural product liparacid A in seven steps.
The Thermal ortho-Substitution of Phenols by Vinyl Ethers
Pyrolysis of a mixture of phenol and 3,4-dihydro-2H-pyran (6) at 150-180 deg C resulted in the formation of 2-(tetrahydro-2H-pyran-2-yl)phenol (3a) in moderate yield.This selective ortho-substitution reaction has been investigated for a range of phenols and a number of vinyl ethers.While it was found to be a fairly general reaction for phenols, only with the vinyl ether (6) and 2,3-dihydrofuran (28a) was the reaction found to be regioselective.Aluminium phenylate strongly catalyses the reaction of phenol with (6), which proceeded under these conditions at room temperature.An ene-type mechanism is proposed for the reaction.
Pinhey, John T.,Xuan, Phan Thanh
p. 69 - 80
(2007/10/02)
REACTION OF PHENOL WITH CYCLOHEXANONE IN THE PRESENCE OF ALUMINUM PHENOLATE
The reaction of phenol with cyclohexanone in the presence of aluminum phenolate leads to a mixture of products of ether and phenolic character and also a mixture of the dimer and trimer of the initial ketone.As a rule 1-(2-hydroxyphenyl)cyclohexene predominates in the mixture.
Kozlikovskii, Ya. B.,Chernyaev, B. V.
p. 1970 - 1973
(2007/10/02)
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