197314-84-4Relevant academic research and scientific papers
Intramolecular hetero-Diels-Alder reactions of functionalized α,β-unsaturated carbonyl compounds: Polycyclic 2H-pyran derivatives
Bogdanowicz-Szwed, Krystyna,Palasz, Aleksandra
, p. 795 - 807 (1999)
The reaction of benzoylacetonitrile, methyl cyanoacetate, and ethyl benzoylacetate with 2-allyloxy-and 2-(3-methyl-2-butenyloxy)-benzaldehyde as well as 2-(3-methyl-2-butenyloxy)-1-naphthaldehyde afforded the corresponding Knoevenagel condensation products. Some of those underwent spontaneous intramolecular cycloaddilion to give cis-fused 2H-pyran derivatives as major products. One-pot reactions of 1,3-cyclohexanedione and 5,5-dimethyl-1,3-cyclohexancdione with 2-(3-inethyl-2-butenyloxy)-benzaldehyde and 2-(3-methyl-2-butenyloxy)-1-naphthaklehyde resulted in Diels-Alder cycloadducts.
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.
