Rotational spectra for the two tautomers (Z)-2-hydroxypyridine and 2-pyridone and their deuterated isotopomers were measured in the microwave range between 4 and 14 GHz using a pulsed beam Fourier transform microwave spectrometer. Nitrogen and deuterium quadrupole hyperfine structure was completely resolved for many of the observed transitions, and the measured 14 N quadrupole coupling tensors are quite different for these two tautomers. The eQq cc (N) values have opposite signs. The 14 N quadrupole coupling strengths for (Z)-2-hydroxypyridine in the principal inertial axis system are as follows: eQq aa (N) ) -0.076(11), eQq bb (N) ) -2.283( 6), and eQq cc (N) ) 2.359(6) MHz. The 14 N and D nuclear quadrupole coupling strengths for (Z)-2-deuteriohydroxypyridine in the principal inertial axis are eQq aa (N) ) -0.1465(4), eQq bb (N) ) -2.2045-(4), and eQq cc (N) ) 2.3510(4) MHz and eQq aa (D) ) -0.0250(9), eQq bb (D) ) 0.1699(4), and eQq cc (D) ) -0.1449(4) MHz. The 14 N quadrupole coupling strengths for 2-pyridone in the principal inertial axis system are eQq aa (N) ) 1.496(4), eQq bb (N) ) 1.269(4), and eQq cc (N) ) -2.765(4) MHz. The 14 N and D nuclear quadrupole coupling strengths for 1-deuterio-2-pyridone in the principal inertial axis system are as follows: eQq aa (N) ) 1.511(2), eQq bb (N) ) 1.249( 5), and eQq cc (N) ) -2.759(5) MHz and eQq aa (D) ) -0.110( 7), eQq bb (D) ) 0.354(6), and eQq cc (D) ) -0.244(6) MHz. New, improved, experimental rotational constants were obtained for the H and D isotopomers of both tautomers. Kraitchman analysis indicates the "tautomeric" hydrogen atom is at a distance of 2.653(2) Å in 2-hydroxypyridine and a distance of 2.124(1) Å in 2-pyridone from the centers of mass of the two tautomers, respectively. The DFT calculated eQq(N) values for both the tautomers and the deuterated tautomers are in good agreement with the present experimental values. The Townes-Dailey model has been used to analyze the new quadrupole coupling data of the tautomers and the results are presented in terms of nitrogen atom p-orbital occupation numbers.
An efficient and regioselective palladium(II)-catalyzed primary acetamide assisted ortho arylation of arylacetamide has been discovered. This is the first report where functionalizable primary acetamide (-CHCONH) is used as a directing group for C(sp)-H activation/cross-coupling reactions, circumventing the extra steps of installation and subsequent removal of the directing groups. The synthetic utility of this transformation is demonstrated through the scale-up synthesis. In addition, the primary acetamide can be manipulated into synthetically important derivatives such as nitriles and carboxylic acids.
An efficient and straightforward method has been developed for the synthesis of polysubstituted phenanthridines from simple aryl iodides and alkyl/aryl nitriles via the palladium-catalyzed nucleophilic addition of aryl iodides to nitriles followed by cascade formation of C-C and C-N bonds viz. in situ generated imine directed sequential two fold C-H activation.
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