Phosphonic acid chemistry. 2. Studies on the Arbuzov reaction of 1-bromo-4,4-diethoxy-2-butyne and Rabinowitch method of dealkylation of phosphonate diesters using chloro- and bromotrimethylsilane

Abstract

graphed 5, mp 62-78 "C, in 20 mL of 95% EtOH was hydrogenated for 20 h at 1 atm over 75 mg of 3096 Pd/C. Filtration, distillation of solvent in vacuo, dissolution of the residue in E h 0 , and isolation A (5 N KOH wash) left 110 mg (98%) of 7: IR 3580,1715 cm-l; 'H NMR r2.60(broads,lH),2.87(broads,2H),5.14(t,J=8.5Hz,lH),6.35 (s,3 H), 8.73 (s,3 H), 8.73 (s,3 H), 8.78 (d, J = 7 Hz, 6 H). This crude 7 in 10 mL of 95% EtOH was hydrogenated for 12 h at 1 atm over 50 mg of 30% Pd/C. Filtration, distillation of solvent in vacuo, dissolution of the residue in EtzO, and isolation A afforded 96 mg (90% based on 5) of 8 as a colorless oil which was crystallized from EtOH-H20 to give 85 :ng (80%) of pure 8 as colorless needles: mp 70-72 OC (lit. 71.5-73 OCI2); UV max 268 nm ( 6 700), 276 (700); IR 1715 cm-'; 'H NMR T 2.70-3.15(m,3H),6.36(~,3H),8.74(~,3H),8.79(d,J=7Hz,6H), 8.80 (s,3 H). IR and lH NMR spectra were identical with those of the authentic (+) enantiomer prepared by CH2Nz esterification of (+)dehydroabietic acid. . Org. Chem., accompanying paper in this issue. (6) The bromo compound has not been isolated in pure form; its formulation is based on two aromatic proton singlets ( r 2.12 and 3.23), a 12.5-Hz doublet at T 5.02 (-CHBrCO-), and a downfield lbmethyi singlet (T 8.51) which accompany resonances of 4 in the 'H NMR spectrum of the mixture: cf.The Arbuzov reaction of the title compound 2 and trimethyl phosphite [(Me0)3P] was shown to yield a mixture of phosphonate and diphosphonate products, the composition of the reaction mixture being a function of reaction conditions. The phosphonates 1,3, and 11 were identified as products of the reaction. The structure of the unexpected allenylphosphonate 11 was established in the usual manner as well as by conversion to the alkenylphosphonate 12. The Arbuzov reaction of 2 and triisopropyl phosphite [(i-PrO)aP] was shown under comparable conditions to yield moderate yields of the 1-alkynylphosphonate 14. Certain interconversions, 1 -3 by A1203 and 1,3, 11diphosphonates, were effected. The Rabinowitch method of dealkylating phosphonate diesters [refluxing chlorotrimethylsilane (MeaSiCl)] was used to convert 3 into 4. Attempts to convert 1 into 5 were unsuccessful. A side product, the alkadienylphosphonate 17, was isolated and characterized. The conversion of 1 into 5 and of 3 into 4 using bromotrimethylsilane (MeaSiBr) was tried unsuccessfully. Reaction mixtures were obtained consistent with the alkadienylphosphonate 26 as being the chief product of these reactions, but work-up yielded no characterizable products.

Dialkyl 1-Alkynylphosphonates: a Range of Promising Reagents

“…For example, from the reaction between triethyl phosphite 4 and propargyl bromide at 90°C only the diethyl 1-propynylphosphonate 18 (R = Et) was isolated in low yields (15%). [25,26] Early transformation of trialkyl phosphites 1 and haloalkynes 2 (R 1 C≡CX) into dialkyl 1alkynylphosphonates 3 was limited to haloalkynes in which R 1 was an electron-withdrawing group. [23,27] In 1990, two innovations worthy of merit were reported.…”

The Hydrolysis of Phosphinates and Phosphonates: A Review

“…The dealkylation of the esters ( 65 ) may also take place with the aid of various reagents, most commonly with TMSX [ 131 , 132 , 133 , 134 , 135 , 136 ]. In the first step, the corresponding bis-trimethylsilyl ester ( 87 ) is formed, which provides the corresponding phosphonic acid ( 66 ) on treatment with water or methanol.…”

Method for Synthesis of Tetrabenzoporphyrin Precursor for Use in Organic Electronic Devices

“…First, we easily synthesized 4-bromo-1,1diethoxy-2-butyne (16) via the reaction between propargyl bromide (15) and triethyl orthoformate, using zinc iodide as the catalyst. 8 We substituted the synthesized compound's acetal function with the aldehyde function using formic acid, and immediately proceeded to synthesize a bicyclic compound (17) by reacting it with 1,3-cyclohexadiene. 9 Using NH 4 OH, we synthesized a pyrrole (13) from the synthesized 17 in an extremely simple manner.…”

“…We introduce a new method that is significantly simpler than other existing methods for synthesizing BCOD-fused porphyrin ( 1 ) (Scheme ). First, we easily synthesized 4-bromo-1,1-diethoxy-2-butyne ( 16 ) via the reaction between propargyl bromide ( 15 ) and triethyl orthoformate, using zinc iodide as the catalyst . We substituted the synthesized compound’s acetal function with the aldehyde function using formic acid, and immediately proceeded to synthesize a bicyclic compound ( 17 ) by reacting it with 1,3-cyclohexadiene .…”