Synthesis of α-Aryldiazophosphonates via a Diazo Transfer Reaction

Abstract

The simple synthetic procedure for preparation of α-aryl-α-diazophosphonates via a diazo transfer reaction is proposed. Benzylphosphonates reacted with tosyl azide (TsN3) in the presence of potassium tert-butoxide (KO t Bu) to afford diazophosphonates in a yield up to 79%. The proposed method is general. The reaction uses easily available starting materials, tolerates various functional groups, and may be applied for multi-gram scale synthesis.

1,3-Dipolar Cycloaddition of Diazophosphonates with Methyl(Ethyl) Acrylate for the Synthesis of 5-Arylpyrazole-3-carboxylates

“…Scheme 2 Summary of results on the synthesis of pyrazolines 1 and 5arylpyrazole-3-carboxylates 2 via 1,3-dipolar cycloaddition reaction of diazo compounds with dipolarophiles Recently we have reported an efficient approach to the synthesis of -aryl--diazophosphonates via diazo transfer reaction. 9 The method uses easily available starting materials (benzylphosphonates and TsN3) and a simple basic reagent (KO t Bu) and tolerates various functional groups giving target diazophosphonates in in a yield up to 79% (usually 55-70%). Three synthetic methodologies were elaborated for different types of aryl moiety in starting benzylphosphonate: 1) bearing electron-withdrawing groups; 2) bearing electron-donating groups; 3) and nitro group containing phosphonates.…”

“…This compound is known. 9 Dimethyl 1-(3,4,5-trimethoxyphenyl)-1-diazomethylphosphonate (3v). Prepared according to general procedure C from dimethyl (3,4,5trimethoxybenzyl)phosphonate; yellow-orange oil (202 mg, 80% yield).…”

“…31 P NMR (162 MHz, CDCl 3 ):  = 20.2. 9 Prepared according to general procedure C from diethyl (4-chlorobenzyl)phosphonate; yellow-orange oil; yield: 200 mg (87%). 10 Prepared according to general procedure C from dimethyl (4-bromobenzyl)phosphonate; yellow-orange oil; yield: 207 mg (85%).…”

Taming of Furfurylidenes by Chiral Bismuth‐Rhodium Paddlewheel Catalysts. Preparation and Functionalization of Optically Active 1,1‐Disubstituted (Trifluoromethyl)cyclopropanes

“…In line with this notion, such diazo derivatives found no applications in synthesis until very recently, when it was shown that they can be generated and processed in flow at low temperature [45] . It is also important to note that the electrocyclic ring opening is not suppressed by imparting a donor/acceptor character onto a furfurylidene of type B , as the corresponding ester (R=COOEt) or phosphonate derivatives (R=P(O)(OR) 2 ) succumb to the very same process with similar ease [43,46,47] . Even attempts to intercept such intermediates by carrying out the diazo decomposition in neat styrene or cyclooctane resulted in very low yields [42] .…”

“…[45] It is also important to note that the electrocyclic ring opening is not suppressed by imparting a donor/acceptor character onto a furfurylidene of type B, as the corresponding ester (R=COOEt) or phosphonate derivatives (R=P(O)(OR) 2 ) succumb to the very same process with similar ease. [43,46,47] Even attempts to intercept such intermediates by carrying out the diazo decomposition in neat styrene or cyclooctane resulted in very low yields. [42] Along the same lines, an attempted copper-mediated reaction of A (R=H, X=NO 2 ) with neat cyclohexene failed to afford any cyclopropane or CÀ H insertion product.…”