Studies on structurally simple αβ-butenolides. IV. behaviour of protoanemonin as electrophile towards alcohols and thiols

Protoanemonin, reacts in different ways with thiolate and alkoxide anions. Thus, while the very soft nucleophile benzenethiolate attacks exclusively the olefinic carbons of 1, alkoxides always attack the carbonyl group in the first step of the reaction. In intermediate cases, when neither very hard nor very soft nucleophiles are used, regioselectivity is not observed. Mechanisms are discussed to explain this differential reactivity.     

Experimental and theoretical study on the structure and vibrational spectra of β-2-aminopyridinium dihydrogenphosphate

Experimental and theoretical vibrational spectra of β-2-aminopyridinium dihydrogenphosphate (β-2APDP) have been investigated. The FT-IR spectrum of β-2APDP was recorded in the region 4000-400 cm(-1). The optimized molecular structure and theoretical vibrational frequencies of β-2APDP have been investigated using ab initio Hartree-Fock (HF) and density functional B3LYP method with 6-311++G(d,p) basis set. The optimized geometric parameters (bond lengths and bond angles) and theoretical frequencies have been compared with the corresponding experimental data and it is found that they agree well with each other. All the assignments of the theoretical frequencies were performed by potential energy distributions using VEDA 4 program. Furthermore, the used scale factors were obtained from the ratio of the frequency values of the strongest peaks in the experimental and theoretical IR spectra. From the results it was concluded that the B3LYP method is superior to the HF method for the vibrational frequencies.