λ⁵-Phosphorus-Containing α-Diazo Compounds: A Valuable Tool for Accessing Phosphorus-Functionalized Molecules

Abstract

The compounds characterized by the presence of a λ-phosphorus functionality at the α-position with respect to the diazo moiety, here referred to as λ-phosphorus-containing α-diazo compounds (PCDCs), represent a vast class of extremely versatile reagents in organic chemistry and are particularly useful in the preparation of phosphonate- and phosphinoxide-functionalized molecules. Indeed, thanks to the high reactivity of the diazo moiety, PCDCs can be induced to undergo a wide variety of chemical transformations. Among them are carbon-hydrogen, as well as heteroatom-hydrogen insertion reactions, cyclopropanation, ylide formation, Wolff rearrangement, and cycloaddition reactions. PCDCs can be easily prepared from readily accessible precursors by a variety of different methods, such as diazotization, Bamford-Stevens-type elimination, and diazo transfer reactions. This evidence along with their relative stability and manageability make them appealing tools in organic synthesis. This Review aims to demonstrate the ongoing utility of PCDCs in the modern preparation of different classes of phosphorus-containing compounds, phosphonates, in particular. Furthermore, to address the lack of precedent collective papers, this Review also summarizes the methods for PCDCs preparation.

BF3·Et2O-Promoted Decomposition of Cyclic α-Diazo-β-Hydroxy Ketones: Novel Insights into Mechanistic Aspects

“…Herein, as a continuation of our interest in diazo chemistry [9,[22][23][24][25][26][27][28][29][30][31], we investigated the cascade rearrangement of destabilized vinyl cations deriving from the BF 3 •Et 2 O-induced decomposition of α-diazo-β-hydroxy ketones, prepared by aldol-type condensation of cyclic ketones with DAA (1). In particular, the effect of solvent and ring size on products distribution and mechanism paths were analyzed and discussed.…”

Continuous Flow Organophosphorus Chemistry

“…Further adaptations of the HWE reaction led to the development of the Seyferth-Gilbert homologation. [138] Dimethyl (diazomethyl)phosphonate is now a common reagent for promoting the homologation of aldehydes and ketones towards the corresponding alkynes. [139] A popular modification relies on 1diazo-2-oxopropylphosphonate (Ohira-Bestmann reagent) to avoid undesirable side-reactions.…”

“…[139] A popular modification relies on 1diazo-2-oxopropylphosphonate (Ohira-Bestmann reagent) to avoid undesirable side-reactions. [138,140,141] Ley and co-workers reported a continuous multistep synthesis system for the preparation of alkynes and triazoles using the Ohira-Bestmann reagent 225 for aldehyde homologations and immobilized reagents for further functionalizations and purifications. [142] A first procedure allowed to generate a variety of alkynes 226 starting from aldehydes 224 and the Bestmann-Ohira reagent 225 in the presence of KOtBu at 100°C for 30 min of residence time (Figure 59(a)).…”

Gold(I)-Catalyzed Intramolecular Cyclization/Intermolecular Cycloaddition Cascade: Fast Track to Polycarbocycles and Mechanistic Insights

“…Reactive metal carbene species participate in a broad range of applications for the effective formation of C-C and C-heteroatom bonds in synthetic organic chemistry [1][2][3][4] . The versatile reactivity of this species is mainly dependent on the choice of catalysts and the substituent(s) proximal to the carbene center 5,6 . The effect of these two variables can be quite pronounced, and novel synthetic transformations could be expected by switching either of these parameters.…”