Photocatalytic Arylation of P₄ and PH₃: Reaction Development Through Mechanistic Insight

Abstract

Detailed 31 P{ 1 H} NMR spectroscopic investigations provided eeper insight into the complex, multi-step mechanisms involved in the recently reported photocatalytic arylation of white phosphorus (P 4 ). Specifically,t hese studies have identified anumber of previously unrecognized side products, which arise from an unexpected non-innocent behavior of the commonly employed terminal reductant Et 3 N. The different rate of formation of these products explains discrepancies in the performance of the two most effective catalysts, [Ir(dtbbpy)(ppy) 2 ][PF 6 ]( dtbbpy = 4,4'-di-tert-butyl-2,2'-bipyridine) and 3DPAFIPN.I nspired by the observation of PH 3 as am inor intermediate,w eh ave developed the first catalytic procedure for the arylation of this key industrial compound. Similar to P 4 arylation, this method affords valuable triarylphosphines or tetraarylphosphonium salts depending on the steric profile of the aryl substituents.

In situ Reaction Monitoring in Photocatalytic Organic Synthesis

“…These experiments visualized the evolution and consumption of primary, secondary and tertiary monophosphine intermediates, and identified traces of Ph 4 P 2 , benzene and Et 2 NH as minor side‐products (Figure 11). A follow‐up study using an organic photocatalyst (3DAFIPN) revealed numerous additional intermediates and side‐products that are derived from a non‐innocent behavior of Et 3 N [51] . Of specific interest was the identification of PH 3 , which prompted the authors to develop an alternative strategy that can directly convert this industrial P 1 precursor to several Ar 3 P and Ar 4 P + products using a similar photocatalytic protocol.…”

3DPAFIPN as a halogenated dicyanobenzene-based photosensitizer catalyzed gram-scale photosynthesis of pyrano[2,3-d]pyrimidine scaffolds

“…The compound 2,4,6-tris(diphenylamino)-5-fluoroisophthalonitrile (3DPAFIPN) has been increasingly utilized in various synthetic procedures that are activated by visible light. Examples of such protocols include intramolecular cyclizations 11 , 12 as well as the formation of C–C 13 , 14 , N–C 15 , and P–C 16 bonds 5 .…”