Green protection of pyrazole, thermal isomerization and deprotection of tetrahydropyranylpyrazoles, and high-yield, one-pot synthesis of 3(5)-alkylpyrazoles

3(5)-Alkylpyrazoles are obtained in high yield from pyrazole by a one-pot procedure.

Stereoselective formation and catalytic activity of hydrido(acylphosphane)(chlorido)(pyrazole)rhodium(iii) complexes. Experimental and DFT studies

Stereoselectivity assisted by hydrogen bond formation, inhibited by steric hindrance, predicted by DFT calculations.

Difluorobenzenes revisited: an experimental and theoretical study of spin-spin coupling constants for 1,2-, 1,3-, and 1,4-difluorobenzene

The experimental spin-spin coupling constants (SSCCs) for 1,3- and 1,4-difluorobenzene have been determined anew, and found to be consistent with previously determined values. SSCCs for 1,2-, 1,3-, and 1,4-difluorobenzene have been analyzed by comparing them with the coupling constants computed using the second-order polarization propagator approximation (SOPPA) and the equation-of-motion coupled cluster singles and doubles method (EOM-CCSD). Eighty experimental values have been analyzed using SOPPA calculations, and a subset of 40 values using both SOPPA and EOM-CCSD approaches. One-bond coupling constants (1)J(C-C) and (1)J(C-F) are better described by EOM-CCSD, whereas one-bond (1)J(C-H) values are better described by SOPPA. An empirical equation is presented which allows for the prediction of unknown coupling constants from computed SOPPA values. A similar approach may prove useful for predicting coupling constants in larger systems.