Direct synthesis of sulfonated azacalixarenes in water.

Successive treatment of cyanuric chloride with two aromatic diamines, at least one of them sulfonated, yields water-soluble sulfonated azacalix[4]arenes which may be isolated by crystallisation. Functionalised azacalixarenes may be made by first displacing two chloro substituents from the cyclisation precursor. Attempted formation of an azacalix[6]arene led to a dimeric species for which two structures may be proposed, one of them an azacalixarene catenane.

Conformational preferences of a polar biaryl: a phase- and enantiomeric purity-dependent molecular hinge.

The favored (R(S)*,M*) diastereoisomer of 2-aryl-pyridine 1 in the solution state results from intramolecular dipole-dipole interactions. In the crystalline state, intermolecular interactions dominate, and the conformation switches reversibly to (R(S)*,P*). Only racemic 1 exhibits this switching property: enantiomerically pure 1 exists as the (R(S)*,M*) diastereoisomer in both the solution and crystalline state.

Controlling axial conformation in 2-arylpyridines and 1-arylisoquinolines: application to the asymmetric synthesis of QUINAP by dynamic thermodynamic resolution.

Unlike related biphenyl compounds, 2-arylpyridines and 1-arylisoquinolines can be induced to adopt preferentially one of two axial conformations by the presence of a sulfinyl substituent adjacent to the Ar-Ar bond. In the case of more substituted biaryls, the compounds are atropisomeric, and thermodynamic selectivities of about 4:1 may be attained on heating. In the case of less hindered compounds, conformer ratios of up to 20:1 may be achieved.

Uterine rupture and epidural analgesia during trial of labour.

A case of complete uterine rupture during a trial of labour in which epidural analgesia was used is described. The pain of uterine rupture was not masked by the addition of fentanyl 25 micrograms to bupivacaine 0.25% 6 ml but was relieved by bupivacaine 0.