98976-94-4Relevant articles and documents
A spectroscopic study of the reduction of geometrically restrained viologens
Benniston, Andrew C.,Harriman, Anthony,Li, Peiyi,Rostron, James P.,Harrington, Ross W.,Clegg, William
, p. 7838 - 7851 (2007)
A small series of N,N′-dimethyl-4,4′-bipyridinium dication derivatives (commonly known as viologens) has been synthesized and fully characterized; a short dialkoxy tether attached at the 3,3′-positions is used to alter the central dihedral angle. These angles were determined by both single-crystal X-ray diffraction and by computational studies made for the dication, radical cation, and neutral species in a solvent reservoir. The dihedral angle derived for the dication controls the first reduction potential, whereas the geometry of the resultant π-radical cation determines the magnitude of the second reduction potential. The optical absorption spectra recorded for the various species, and especially those of the radical cations, and the EPR spectral parameters of the π-radical cations also depend on the molecular geometry. In particular, the central dihedral angle influences the spin density distribution around the aromatic nucleus and, by way of comparison to the parent viologen, it has been possible to resolve the angle dependence from the inherent inductive effect of the strap. These results are considered in terms of the degree of electronic communication between the two aromatic rings, as controlled by the length of the tether.
Nickel-catalyzed cross-coupling reaction of carbamates with silylmagnesium reagents
Murugesan, Vetrivelan,Balakrishnan, Venkadesh,Rasappan, Ramesh
, p. 293 - 298 (2019/08/12)
The C–O bonds are kinetically inert in cross-coupling reactions compared to those of carbon–halogen bonds. Thus, developing methodologies for the activation of C–O bonds in cross-coupling reactions remains a major challenge. We disclose an unprecedented nickel mediated cross-coupling of carbamates with silylmagnesium reagents that does not require the expensive silylboranes. Silylmagnesium reagents were prepared from either silyllithium or silyl iodides. This methodology is distinguished by the synthesis of trimethylsilyl coupled product and its synthetic applications. Kinetic studies and radical clock experiments revealed the rate-limiting C–O bond cleavage, half order with respect to the catalyst and a non-radical transition state.
Synthesis of two conformationally constrained analogues of the minor tobacco alkaloid anabasine.
Lindstroem,Ripa,Hallberg
, p. 2291 - 2293 (2007/10/03)
The anabasine analogues spiro[4-azaindan-1,2'-piperidine] (7) and spiro[6-azaindan-1,2'-piperidine] (8) have been prepared. A series of palladium-catalyzed reactions, where an intramolecular cyclization constituted a key reaction, were utilized for the pr
