The quest for unligated oxaphosphiranes with phosphorus in different coordination numbers.

After more than 160 years of oxirane (epoxide) chemistry, the first derivative of a phosphorus analogue, namely oxaphosphirane, has been synthesized. Reactions with borane sulfane, a peroxy compound and elemental sulfur, as well as tetra-chloro--benzoquinone (TOB) reveal a significant destabilization upon increasing the coordination number at phosphorus from σ to σ, thus somehow supporting previous reports on such fleeting species. Theoretical studies provide insight into ring strain energy, ring/ring interconversion and the oxidation pathways.

Unconventional ionic ring-deconstruction pathways of a three-membered heterocycle.

Two different ionic deconstructions of a three-membered COP ring have been discovered. The first involves displacement of the C[double bond, length as m-dash]O unit (aldehyde elimination) induced by base whilst the second involves acid-initiated extrusion of the ring-carbon (2-methyl-2-butene). Insight into the latter deconstruction was obtained by quantum chemical calculations.