The title complex, [Ni2Br2(C2H8N2)4]Br2, consists of two bromide anions and a complex dication. The dication is a centrosymmetric unit of two Ni atoms bridged unsymmetrically by two Br atoms. The Ni atoms are pseudo‐octahedral, six‐coordinate, with four N atoms from two 1,2‐diaminoethane ligands completing the coordination environment.
An exquisite Pybox/Cu(OTf)2-catalyzed asymmetric tandem reaction of tertiary enamides was developed, which enabled the expeditious synthesis of indolizino[8,7-b]indole derivatives in high yield, excellent enantioselectivity and diastereoselectivity.
Starting
from readily available tetratriflated resorcin[4]arene
derivatives, C
4-symmetric 1,3,5,7(1,3)-tetrabenzenacyclooctaphane
tetraamines were synthesized conveniently by means of Pd-catalyzed
C–N bond coupling reaction with diphenylmethanimine followed
by hydrolysis. Subsequent Sandmeyer reaction and sulfonylation reaction
efficiently afforded the corresponding tetraazide and tetrasulfonamide
products, respectively. Upon treatment with PhI(OAc)2,
tetrasulfonamides underwent facile oxidative transannular cyclization
reaction to produce mono- and dispiro macrocyclic compounds selectively
rather than N4-octahydrobelt[8]arenes. Conformational structures
of resulting macrocycles are presented, and the reaction mechanism
is discussed.
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