(2SR,3RS)-Methyl 2-(adamantan-1-yl)-3-phenyl-sulfonyl-3-(pyridin-2-ylsulfan-yl)propano-ate dichloro-methane hemisolvate.

The title compound, C(25)H(29)NO(4)S(2) 0.5CH(2)Cl(2), was obtained as a racemate. The pyridine and phenyl rings are arranged face-to-face, giving a weak intra-molecular π-π inter-action [centroid-centroid separation = 3.759 (3) Å]. These inter-actions are extended inter-molecularly, forming chains of stacked rings along [001] with separations of 3.859 (3) and 3.916 (3) Å. The solvent used for crystallization, CH(2)Cl(2), is located in voids between the chains of mol-ecules, with a site occupancy of 0.5.

Radical contraction of 1,3,2-dioxaphosphepanes to 1,3,2-dioxaphosphorinanes: a kinetic and (17)O NMR spectroscopic study.

Two diastereomeric 5-bromo-4-phenyl-2-phenoxy-2-oxo-1,3,2-dioxophosphepanes have been synthesized and used to study the contraction of 4-phenyl-2-phenoxy-2-oxo-1,3,2-dioxophosphorinan-5-yl radicals. Kinetics were determined by competition methods and demonstrate Arrhenius parameters typical of rearrangements of this kind. Isotopic labeling reveals that all rearrangements are formally of the 1,2-type with retention of configuration at phosphorus. Analysis of the stereochemistry of the rearrangements, however, reveals the two diastereomers to take different paths with respect to the geometry of the presumed alkene radical cation intermediate.