A Staudinger/aza‐Wittig reaction sequence is described that is catalytic in phosphorus. Towards this end, the phosphane oxide is reduced in situ by diphenylsilane, which allows for substoichiometric amounts of the catalyst 5‐phenyldibenzophosphole to be used. The substrate scope is investigated and benzoxazoles, benzodiazepine imidates and a 2‐methoxypyrrole were successfully synthesized. These investigations show that a fast aza‐Wittig reaction is required to obtain high yields.

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Catalytic Staudinger/Aza-Wittig Sequence by in situ Phosphane Oxide Reduction.-A Staudinger/aza-Wittig process using catalytic amounts of 5-phenyldibenzophosphole is described. The process involves in situ reduction of the phosphine oxide to complete the catalytic cycle. The process is readily amenable for the synthesis of benzoxazoles, benzodiazepines, and a pyrrole. -(VAN KALKEREN, H. A.; TE GROTENHUIS, C.; HAASJES, F. S.; HOMMERSOM, C. A.; RUTJES, F. P. J. T.; VAN DELFT*, F. L.; Eur. J. Org. Chem. 2013, 31, 7059-7066, http://dx.doi.org/10.1002/ejoc.201300585 ; Inst. Mol. Mater., Radboud Univ. Nijmegen, NL-6525 AJ Nijmegen, Neth.; Eng.) -Mais 13-195

The cover picture shows a 5‐phenylbenzophosphole with proven efficacy in various organophosphorus‐catalyzed reactions. In their paper, the authors demonstrate its applicability in a Staudinger/aza‐Wittig reaction sequence involving reactive phosphole regeneration by in situ phosphole oxide reduction. Based on this principle, full conversions can be achieved with substoichiometric amounts of phosphane, thereby reducing the amount of phosphane oxide waste products. A range of benzoxazoles, benzodiazepine imidates, and a 2‐methoxypyrrole were successfully synthesized, as detailed in the article by F. L. van Delft et al. on