2,2 -Bifuran derivatives

The bifuran-derived corrole derivative 2.39 was later subjected to metalation... 

The bifuran-containing corrole 2.39 was also subject to acylating conditions. In this instance, treatment of corrole 2.39 with acetyl chloride using aluminum trichloride as the Lewis acid afforded the C(5)-acetyl-substituted corrole derivative 2.245 in 31% yield (Scheme 2.1.89). In addition to this product, a di-substituted corrole was also obtained. This was presumed to be either a 2,18- or a 3,17-diacetyl-substituted corrole. However, no evidence was put forward in support of either of these assignments. 

An alternative synthesis of these mono-phenyl-substituted rosarinogens was also developed by Sessler and his group. In this instance, the phenyl-substituted tetrapyrrane derivative 7.50 was reacted with the diformyl bipyrrole 7.21. While this approach afforded the rosarinogen macrocycle 7.49 in only moderate yield, an advantage of this method is that it is potentially amenable to heteroatom substitution (Scheme 7.4.3). Indeed, it has already been found that using the diformyl bifuran 7.51 in place of the diformyl bipyrrole 7.21 affords the dioxarosarinogen 7.52. ... 

Compounds 124 and 127 were studied at the lowest ab initio level (STO-3C) to conclude that the structures correspond to fully planar s-cis (both heteroatoms on the same side, sZ) and s-trans forms (sE), the former being the most stable (81 JCS(P2)127). STO-3C and 4-31C calculations were carried out on bifurans 115,116, and 117 by Orti and Tomas (84THE(108) 199), the authors conclude that the sE/sZ preferences depend on the position of the oxygen atoms in the case of 115 the preferred conformation is the sE. A similar conclusion (STO-3C calculations) was reached for bithienyls 119 and 120 where for 118 the most stable conformation is the sE (86JCS(P2)907) in this case the rotational barrier was calculated (25.1 kj mol ) and it agrees with that determined by DNMR (21 8 kJ mol, see Section 2.9). Compounds 115, 118, the Se and Te analogues as well as mixed derivatives were studied at the B3LYP/6-311 ++C(d,p) and... 

AFL are a group of related coumarin derivatives the bifuran nucleus and the pentaheterocyclic arrangement lend rigidity to their structure. There are several known AFL (National Centerfor Biotechnology Information, 2007), but most of these are metabolites formed endogenously in animals and humans or AFL derivatives... 

Li P, Chai Z, Zhao G, Zhu S-Z (2008) Synthesis of 3-fluoro-2,5-disubstituted furans and further derivative reactions to access fluorine-containing 3,3 -bifurans and tetrasubstituted furans. Synlett 2547-2551... 

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