Thiophosphonium–Alkyne Cycloaddition Reactions: A Heavy Congener of the Carbonyl–Alkyne Metathesis

Abstract

While the metathesis reaction between alkynes and thiocarbonyl compounds has been thoroughly studied, the reactivity of alkynes with isoelectronic main group R 2 E=S compounds is rarely reported and unknown for [R 2 P=S] + analogues. We show that thiophosphonium ions, which are the isoelectronic phosphorus congeners to thiocarbonyl compounds, undergo [2 + 2]-cycloaddition reactions with different alkynes to generate 1,2-thiaphosphete ions. The four-membered ring species are in an equilibrium state with the corresponding P=C–C=S heterodiene structure and thus undergo hetero-Diels–Alder reactions with acetonitrile. Heteroatom and substituent effects on the energy profile of the 1,2-thiaphosphete formation were elucidated by means of quantum chemical methods.

Hybrid Inorganic–Organic Cross-Metathesis between Diborenes and Acetylene

“…25−31 In fact, hybrid inorganic−organic cross-metathesis is limited to a couple of recent publications by Dielmann and co-workers, showing the reversible cycloaddition/metathesis between terminal alkynes and the oxo-and thiophosphonium species [Y 2 PE] + (E = O, S; Y = NIDip, IDip =1,3bis(2,6-diisopropylphenyl)imidazol-2-ylidene), a heavy congener of the alkyne−carbonyl metathesis (Scheme 1d). 32,33 However, there have been, to our knowledge, no reports of cross-metathesis reactions between homodinuclear organic and inorganic main-group multiple bonds.…”