Chemistry of Phosphorylcarbenes

Abstract

Phosphorylcarbenes, which have become known only recently during synthetic experiments in the field of phosphoryldiazoalkanes, have twofold preparative value. In the first place, they can be used to introduce phosphoryl groups into organic compounds, as in the phosphoryl‐cyclopropanation of alkenes or arenes and in the phosphorylcyclopropenation of alkynes. Secondly, phosphorylcarbenes readily undergo rearrangements; hydride, alkyl, aryl, or acyl shifts lead to phosphorylated alkenes. The phosphorylcarbene/methylenephosphane oxide rearrangement provides access to the short‐lived P analogs of the ketenes. Finally, the vinylcarbene/allene rearrangement was first discovered in this connection; it competes with ring closure to the cyclopropene.

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

“…The structure-assignment of the products was carried out using IR and NMR analyses (Scheme 47). 27,99 Later, Tomioka's group reported additional studies on the photochemistry of α-diazobenzylphosphonates showing that the reactivity of the phosphorylcarbenes, photolytically generated in alcohols, was strongly temperature-dependent. 100 In particular, the photolysis of dimethyl α-diazobenzylphosphonate (11b) in alcohol at 27 °C gave the O−H insertion product 106 in 70% yield along with a small amount of dimethyl benzylphosphonate 107 (<3%).…”

“…Reference source not found.). 99,100 " he e . showing that dramatic and significant increases in the C-H insertion product occurred when the reaction phase was changed from liquid to solid due to the decreased temperature.…”

“…The cyclopropanation of alkene bonds is one of the most investigated areas in PCDC chemistry. It does not sound surprising because the cyclopropane ring is an important structural motif in biologically active compounds, , as well as a versatile building block able to be converted into a range of other functionalities. − In this type of transformation, the use of transition-metal catalysts, including copper-, rhodium-, and ruthenium-catalyst, has represented the method of choice for generating the corresponding reactive species, although some examples employing photochemical-induced nitrogen elimination have also to be cited. ,− High diastereo- and enantio-control have been achieved by the use of a number of chiral transition metal complexes, rhodium- and ruthenium-based catalysts, in particular. However, the possibility to direct the reaction toward the preferential formation of the cis isomer remains unsuccessful.…”

“…The reaction of arenes with photochemically generated phosphorylcarbenes (the Buchner reaction), leading to an equilibrating mixture of the corresponding norcaradiene and cycloheptatriene derivatives, was reviewed by Regitz . Later, Maas et al reported about the substituent dependence of this equilibrium …”

“…25,26 The huge number of transformations that can occur with PCDCs makes them extremely versatile reactants in the scenario of synthetic chemistry for the preparation of molecules functionalized with a phosphorus-based moiety. Although in general PCDC-based reactions have several advantages, such as mild reaction conditions and the possibility to work with multifunctional substrates, so far the chemistry of PCDCs has been never surveyed, except for an old Regitz's review, 27 a short paragraph in a book chapter, 28 and isolated examples, which are highly dispersed over the literature on diazo-compounds. With the aim to fill this gap, our primary purpose in writing this Review is to demonstrate the ongoing utility of PCDCs in the modern preparation of different classes of phosphorus-containing compounds, in particular phosphonates.…”