Bidding-ring

A simple model for this compound with both the five-rings planar gives an O — O distance oi about bid A, while BbSlEGOBBS [3] value for the covalent radius of oxygen is 1 23 A. Consequently there must be... 

C. A. Collyer, K. Henrick, and D. M. Blow, Mechanism for aldose-ketose interconversion by D-xylose isomerase involving ring opening followed by a 1,2-hydride shift, J.Mol.Bid. 1990, 212, 211-235. 

The aromaticity of benzene is linked, in spin-coupled theory, to the particular mode of coupling of the electron spins, and so it seems reasonable to suppose that the orbital descriptions of Dih cyclobutadiene and of benzene could be fairly similar, but for these to be associated with very different modes of spin coupling. To a first approximation, this indeed turns out to be the case. With benzene-like orbitals ordered a,b,c,d around the ring, the symmetry requirements of an overall Bu state are such that the electron spins associated with each diagonal (ale and bid) must be strictly triplet coupled. These two triplet subsystems combine to a net singlet. A characteristic feature of antiaromatic situations in spin-coupled theory is the presence of such triplet-coupled pairs of electrons. 

Aminolysis reactions of epoxides have been reported to be catalyzed by BiCh [81a-c] or Bi(0Tf)3-%H20 (Equation 38) [81d-f. The Bids-catalyzed ring opening... 

The synthesis of trans-1,2-diamines via the ring opening of aziridines has been reported to be catalyzed by Bids (10 mol%) in acetonitrile [87]. Interestingly, the use of Bi(0Tf)3 xH20 as a catalyst under the same conditions and solvent gave N-substituted P-amino nitriles instead [88]. 

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