4352-89-0Relevant articles and documents
Lewis acid-catalyzed annulative partial dimerization of 3-aryloxyacrylates to 4-arylchroman-2-ones: Synthesis of analogues of tolterodine, RORγ inhibitors and a GPR40 agonist
Kunkalkar, Rupesh A.,Fernandes, Rodney A.
supporting information, p. 2313 - 2316 (2019/02/27)
A beguiling annulative partial dimerization of 3-aryloxyacrylates to 4-arylchroman-2-ones catalyzed by Lewis acid (BF3·OEt2) has been developed. The reaction involves two molecules of 3-aryloxyacrylate, resulting in the loss of one propiolate molecule to furnish 4-arylchroman-2-one, an important structural motif found in many natural products. This methodology has been elaborated to synthesize analogues of tolterodine, RORγ inhibitors and a GPR40 agonist.
Synthesis of fused furans by gas-phase pyrolysis of 2-allyloxyaryl-propenoic esters
Black, Michael,Cadogan,McNab, Hamish,MacPherson, Andrew D.,Roddam, V. Peter,Smith, Carol,Swenson, Helen R.
, p. 2483 - 2493 (2007/10/03)
Flash vacuum pyrolysis of 2-allyloxypropenoic esters (e.g. 7) gives benzo[b]furans (e.g. 32) in synthetically useful yields by sequential generation of a phenoxyl radical, cyclisation and ejection of the carboxylic ester function as a free radical leaving group. The method is compatible with a range of substituents on either the benzene ring or the propenoate chain, and is particularly effective for 2-substituted benzo[b]furans. The natural products 5-methoxybenzo[b]furan 1 and angelicin 2 have been synthesised in three and four steps respectively from commercially available starting materials by this route. Related cyclisations to give naphtho[2,1-b]furan 40 were complicated by competitive formation of naphtho[2,1-b]pyran-3-ones (e.g. 41 and 42), but the yield of the required product could be optimised by the choice of the radical precursor. Annelation of a furan ring onto a thlophene is also possible by this method, but lower yields are obtained in such pyrolyses.
