Synlett 2019; 30(16): 1867-1885
DOI: 10.1055/s-0039-1690129
account
© Georg Thieme Verlag Stuttgart · New York

The Fascinating World of Phosphanylphosphonates: From Acetylenic Phosphaalkenes to Reductive Aldehyde Couplings

Juri Mai
,
Sascha Ott
Department of Chemistry, Ångström Laboratory, Uppsala University, Box 523, 75120 Uppsala, Sweden   Email: sascha.ott@kemi.uu.se
› Author Affiliations
We gratefully acknowledge the funding supplied by Uppsala University and the Swedish Research Council for our group’s activities in phosphaorganic chemistry.
Further Information

Publication History

Received: 14 June 2019

Accepted after revision: 06 July 2019

Publication Date:
13 August 2019 (online)


Dedicated to Professor Rüdiger Faust

Abstract

This account highlights the versatility of phosphanylphosphonates, which can be used for the preparation of phosphorus-containing π-systems and as reagents for the reductive coupling of carbonyl compounds to alkenes. Phosphanylphosphonates with metal fragments coordinated to the P-lone pair have been known for a long time and they have been used for the synthesis of phosphaalkenes by means of the phospha-Horner–Wadsworth–Emmons reaction. With the original aim of incorporating phosphorus heteroatoms into classical all-carbon ethynylethene scaffolds, we entered the field of phosphanylphosphonates with the discovery that these compounds engage in complex cascade reactions with acetylenic ketones, forming 1,2-oxaphospholes, cumulenes, and bisphospholes. Later, we synthesized the first metal-free phosphanylphosphonate, which reacts with aldehydes to yield phosphaalkenes, but gives phospholones when diacetylenic ketones are used as substrates. In the final part of the account, we outline our discovery and the development of an unprecedented carbonyl–carbonyl cross-coupling reaction. This protocol offers a straightforward method for the synthesis of nonsymmetric 1,2-disubstituted alkenes directly from two dissimilar aldehydes.

1 Combining Acetylenes with Phosphaalkenes

2 Synthetic Examples of Acetylenic Phosphaalkenes

3 The Phospha-Horner–Wadsworth–Emmons Approach to Phosphaalkenes

3.1 Metal-Coordinated Phosphanylphosphonates

3.2 Mechanism of the Phospha-Horner–Wadsworth–Emmons Reaction

3.3 The First Metal-Free Phosphanylphosphonate and Its Reactivity with Aldehydes

4 Reactions with Acetylenic Ketones

4.1 Metal-Coordinated Phosphanylphosphonate and Monoacetylenic Ketones

4.2 Metal-Coordinated Phosphanylphosphonate and Diacetylenic Ketones

4.3 Metal-Free Phosphanylphosphonate and Diacetylenic Ketones

5 Metal-Free Phosphanylphosphonate as a Coupling Reagent for Aldehydes

6 E-Alkenes by the Reductive Coupling of Two Aldehydes

7 Conclusions and Outlook