99558-32-4Relevant academic research and scientific papers
C-H bond functionalization via hydride transfer: synthesis of dihydrobenzopyrans from ortho-vinylaryl akyl ethers
McQuaid, Kevin M.,Long, Jonathan Z.,Sames, Dalibor
supporting information; experimental part, p. 2972 - 2975 (2009/12/05)
The hydride transfer initiated cyclization ("HT-cyclization") of aryl alkyl ethers, which leads to direct coupling of sp3 C-H bonds and activated alkenes, is reported. Readily available salicylaldehyde derived ethers are converted in one step to dihydrobenzopyrans, an important class of heteroarenes frequently found in biologically active compounds. This process has not been previously reported, in contrast to known HTcyclizations of the corresponding fert-amines ("tert-amino effect" reactions).
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.
Carboxylic Esters as Radical Leaving Groups: A New and Efficient Gas-phase Synthesis of Benzofurans
Black, Michael,Cadogan, J. I. G.,Cartwright, Gary A.,McNab, Hamish,MacPherson, Andrew D.
, p. 959 - 960 (2007/10/02)
Flash vacuum pyrolysis (FVP) of o-allyloxycinnamate esters gives benzofurans in high yield, via cyclisation of a phenoxyl radical and subsequent cleavage of the carboxylic ester function; coumarins are obtained by FVP of the corresponding phenols.
