Diethyl diazomethylphosphonate

Addition of tosylazide to diethyl 1-formylalkylphosphonate yields the corresponding triazoline which evolves to diethyl diazomethylphosphonate (Scheme 5.78). ... 

Addition at room temperature of diethyl diazomethylphosphonate to aldehydes in (dl Ch in the presence of catalytic amounts of SnCl2 results in the formation of the corresponding diethyl P-ketoalkylphosphonates (Scheme 7.52). However, the yields of P-ketophosphonates are highly dependent on the nature of the aldehydes, and the reaction works well only with unencumbered aldehydes. ... 

CuOTf is an outstandingly effective catalyst for the synthesis of cyclopropyl phosphonates by the reaction of diethyl diazomethylphosphonate with alkenes (eq 6). The resulting cyclopropylphosphonates are useful intermediates for the synthesis of alkylidenecyclopropanes by Wadsworth-Emmons alkena-tion with aromatic carbonyl compounds (eq 7). ... 

A study of the kinetics and products of the thermolysis of a series of diaryl-phosphinic azides has been reported.119 Diethyl 1-diazomethylphosphonates undergo an aldol-type reaction with aldehydes to give l-diazo-2-hydroxyalkylphosphonates (152).120 Acidification of the diazophosphonates (153) possessing a chiral phosphorus centre yields mixtures of diastereoisomers (154) and epimers at C. For given R1 and R2, the reaction becomes increasingly stereoselective for X= OAc < Cl < OTs. It may be argued that protonation of (153) will yield a mixture of diastereoisomeric di-... 

Dimethylchromanes, 317 (2S,6S)-2,6-Dimethylcyclohexanone, 11 Dimethyl diazomethylphosphonates, 157 o,o -Dimethyldibenzylamide, 245 Dimethylformamide diethyl acetal, 157 Dimethylformamide dimethyl acetal, 158 Dimethyl fumarate, 302... 

Recently, the synthesis of dithio- and diselenoacetals of formylphosphonates by the BF3 EtjO-catalyzed reaction between dialkyl diazomethylphosphonate and disulfides or diselenides has been reported." The reaction proceeds by the insertion of the dialkoxyphosphorylcarbene moiety into the S-S or Se-Se bonds of the disulfide or diselenide. Preparation of diethyl 1,1 -/ .v(me thylthio )meth-ylphosphonate is generally carried out in methyl disulfide as solvent, and it has been found that both BFj Et2O and disulfide had to be used in excess to produce the expected dithioacetal in a good yield (85%)." ... 

The carboxyphosphonates are the oldest and the most popular functionalized phosphonates. They are precursors of several reagents often used in organic synthesis such as diethyl l-(hydroxycar-bonyl)rncthy I phosphonate, dialkyl l-(alkoxycarbonyl)viny Iphosphonates, and dialkyl 1 -(alkoxycar-bony I)-1 -diazomethylphosphonates. The are known for their valuable role in organic synthesis and in the recent development of the chemistry of Foscamet and (o-amino-co-(hydroxycarbonyl)alkyl-phosphonic acids. This chapter deals with their preparations and transformations. 

Diethyl l-tert-butoxycarbonyl-l-diazomethylphosphonate is efficiently prepared in 81% yield from the sodium salt of diethyl l-(tert-butoxycarbonyl)methylphosphonate and tosyl azide in DME (Scheme 8.22). In the case of sodium and potassium salts of diethyl l-(methoxycarbonyl)eth-ylphosphonate, the desired azides are not formed. However, with alkoxymagnesium derivatives, the 1-azido-l-(methoxycarbonyl)ethylphosphonates are obtained in modest yields. Diazotation of diethyl 1-amino-l-(ethoxycarbonyl)methylphosphonate with n-PrONO in AcOH gives diethyl 1-ethoxycarbonyl-l-diazomethylphosphonate in 56-74% yields. ... 

Otlier preparative methods for phosphorylglycines include the addition of sodium diethyl pliosplute to the Schiff base prepared from benzylamine and ethyl or ferf-butyl glyoxalate - the reaction of McjSiBr with the triethoxyphosphorane prepared from Af-protected alkyl oxalamides and trietliyl phosphite and the Rh(II)-catalyzed N-H insertion of diethyl 1-ethoxycarbonyl-l-diazomethylphosphonate into carbamates. 

The azido/n.v(dicthykirnino)phosphoniurn bromide appears to be an exceptionaly safe diazo reagent stable to shock, friction, heating, and even flame.It reacts smoothly with diethyl 1-(ethoxycarbonyl)methylphosphonate in Et2O at room temperature in the presence of t-BuOK or another alkoxide to give diethyl 1-ethoxycarbonyl-l-diazomethylphosphonate in 70% yield (Scheme 8.32). 5 5 ° Mild diazo transfer has recently been achieved in excellent yields (85%) through the use of para-acetamidobenzenesulfonyl azide at O C ... 

An attractive nonbasic variant involving the use of AEOg KF as solid base results in the formation of diethyl 1-ethoxycarbonyl-l-diazomethylphosphonate in excellent yield (96%). This method has the advantages of simple workup, easy product isolation, and mild conditions. 

Thermal decomposition of diethyl 1-ethoxycarbonyl-l-diazomethylphosphonate catalyzed by Rh2(OAc)4 in the presence of propylene oxide gives diethyl 1 -ethoxycarbonyl- 1-oxomethyIphos-phonate.5 Although stable under anhydrous conditions, this compound hydrates quantitatively in H2O, giving the gem-diol, whereas MeOH adds quantitatively to form the hemiketal. ... 

The anion of diazomethyltrimethylsilane, or, better, the more stable and easily prepared anions of the diethyl or dimethyl diazomethylphosphonates, condenses readily with carbonyl compounds to give the homologous alkynes [e.g. (137)->(138) (Scheme 35)]. The reaction also works well on preparing diaryl-alkynes but does not offer a route to mono- or di-alkylalkynes. 

Palladium-catalysed arylation of diethyl a-diazomethylphosphonate (529) with aryl iodides (530) has been described as an efficient pathway for generation of arylated diazophosphonates (531). The synthetic utility of the newly obtained diazo compound (531) (R = N02) has been futher demonstrated in cyclopropanation, epoxidation, N-H and O-H insertion reactions leading to products (532)-(535) (Scheme 156). ... 

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