Solvent effects on the structural and formyl substrate reactivity properties of a nitrogen/sulfur-ligated zinc hydroxide complex

The solution structural and formyl substrate reactivity properties of a nitrogen/sulfur-ligated zinc hydroxide complex, [(bmnpaZn)2(mu-OH)2](ClO4)2 (1, bmnpa = N,N-bis-2-(methylthio)ethyl-N-((6-neopentylamino-2-pyridyl)methyl)amine), in acetonitrile and methanol are reported. In CH3CN, 1 has a binuclear cation [(bmnpaZn)2(mu-OH)2]2+ that is stabilized by secondary hydrogen bonding and CH/pi interactions involving the bmnpa chelate ligand. In CH3OH, 1 undergoes reaction with solvent to yield a zinc methoxide species, as determined by 1H NMR and electrospray mass spectral analysis. Treatment of 1 with methyl formate in CH3CN results in stoichiometric hydrolysis of the formyl ester to produce [(bmnpa)Zn(O2CH)]ClO4 (2) and methanol. The formate complex was identified via independent synthesis and characterization (X-ray crystallography, 1H and 13C NMR, FTIR, LRFAB-MS, conductance, and elemental analysis). In the solid state, 2n has a formate-bridged coordination polymer-type structure. However, in CH3CN, 2 behaves as 1:1 electrolyte, indicating cleavage of the polymer structure into mononuclear [(bmnpa)Zn(O2CH)]ClO4 species. Treatment of 1 with a stoichiometric amount of formanilide in CH3CN for 48 h at 45 degrees C results in decomposition of the zinc hydroxide complex to yield the free bmnpa ligand and an inorganic solid, presumably a zinc hydroxide or oxide species. Treatment of 1 with a stoichiometric amount of ethyl formate in CD3OD results in rapid, quantitative transesterification of the formyl carboxylate ester. A control reaction indicates that this transesterification reaction does not occur on the same time scale in the absence of the catalyst. Treatment of 1 with an excess of ethyl formate in CD3OD results in catalytic formyl carboxylate ester transesterification, with approximately 1000 turnovers in 60 min at 22(1) degrees C. Treatment of a CD3OD solution of 1 (0.5 equiv) with formanilide (1 equiv) results in the formation of aniline, d3-methyl formate, and the zinc formate complex 2. While aniline is produced stoichiometrically, the yield of d3-methyl formate varied from 30 to 50%, and the yield of 2 varied from 50 to 70% in repetitive experiments. Formation of both d3-methyl formate and 2 indicates that both methanolysis and hydrolysis reactions take place.     

A norbornenyl derivative with through‐space ketone π‐interaction

The title compound, endo,exo‐12‐oxotetra­cyclo­[6.2.1.1^3,6.0^2,7]­dodeca‐9‐en‐anti‐11‐yl p‐bromo­benzoate, C₁₉H₁₇BrO₃, con­sists of norbornene with an anti‐p‐bromo­benzoate substituent at the methano bridge and an exo‐fused norbornanone unit bonded to the ethano bridge. The spatially proximate ketone and alkene interact through space and the ketone C atom is substantially pyramidalized. Through‐space ketone π‐inter­action is probably responsible for the low solvolysis rate of the anti‐11‐chloride derivative.