121029-82-1Relevant articles and documents
Aryl Boronic Acid Catalysed Dehydrative Substitution of Benzylic Alcohols for C?O Bond Formation
Estopi?á-Durán, Susana,Donnelly, Liam J.,Mclean, Euan B.,Hockin, Bryony M.,Slawin, Alexandra M. Z.,Taylor, James E.
, p. 3950 - 3956 (2019/02/16)
A combination of pentafluorophenylboronic acid and oxalic acid catalyses the dehydrative substitution of benzylic alcohols with a second alcohol to form new C?O bonds. This method has been applied to the intermolecular substitution of benzylic alcohols to form symmetrical ethers, intramolecular cyclisations of diols to form aryl-substituted tetrahydrofuran and tetrahydropyran derivatives, and intermolecular crossed-etherification reactions between two different alcohols. Mechanistic control experiments have identified a potential catalytic intermediate formed between the aryl boronic acid and oxalic acid.
Gold-catalysed cyclic ether formation from diols
Jiang, Xiaolu,London, Emma K.,Morris, David J.,Clarkson, Guy J.,Wills, Martin
experimental part, p. 9828 - 9834 (2011/02/23)
Gold(I) and (III) salts have been found to be highly effective at the catalysis of ether formation from alcohols. Intramolecular ether formation of a 1,5-diol was also achieved, with a stereoselectivity that indicates that an SN1 mechanism predominates. In an attempt to form a seven-membered ring, a stable 14-membered dimer product was also formed. Attempts to control the diastereoselectivity of the reaction using a chiral anionic counterion did not give products with a high de.
Scope of alkoxymethyl radical cyclizations
Rawal,Singh,Dufour,Michoud
, p. 7718 - 7727 (2007/10/02)
We have explored different aspects of the cyclization capability of alkoxymethyl radicals and report here a full account of our investigations. The required radicals were generated from (phenylseleno)-methyl ethers (e.g., 6), which were prepared from homoallylic or bis-homoallylic alcohols by a two-step process. The alcohols were alkylated with (iodomethyl)tributylstannane. The stannanes were reacted with n-BuLi, and the resulting α-alkoxyanions were trapped with diphenyldiselenide to give the (phenylseleno)methyl ethers, which were stable to chromatography. When treated with tributyltin hydride, in the presence of a radical initiator, these precursors undergo a smooth cyclization to substituted tetrahydrofurans and tetrahydropyrans. Formation of the cyclization product was found to be the primary pathway even at relatively high tin hydride concentration. The diastereoselectivity of this cyclization was comparable to that observed in other radical cyclizations. The cis selectivity in cyclization of 6 increased gradually (up to 11:1) as the reaction temperature was lowered. The cyclization can be used for the synthesis of bicyclic and tricyclic compounds and can be incorporated in systems capable of tandem cyclizations.
