A Simple Sonochemical Synthesis of (3-Thienyl)trimethylsilane

Synthesis and structural studies (1H,13C,31P NMR and X-ray) of new C-bonded cyclotriphosphazenes with heterocyclic substituents from novel phosphinic acid derivatives

“…Firstly, the N,N-diethylphosphinic amide 7 was obtained (66%) by reaction of dichloro-N,N-diethylphosphinic amide 12 with the Grignard reagent of 2-bromothiophene. 13 Then, in the presence of concentrated hydrochloric acid, it gave di(2-thienyl)phosphinic acid (8), which was easily recovered by filtration of the reaction mixture (98%). The phosphinic acid 8 itself led to di(2-thienyl)phosphinic amide (1) in two steps.…”

“…The reaction of 1 with the Appel reagent (Scheme 1) gave the expected cyclotriphosphazene 2 (34%), together with triphenylphosphine oxide. With the aim to reduce the number of steps needed to synthesise the di(2-thienyl)-phosphinic amide 1, trichlorophosphine oxide was allowed to react with varying amounts of the Grignard reagent of 2-bromothiophene 13 in THF (Scheme 3). The reaction was followed by recording 31 P spectra of the reaction mixtures using conditions for quantitative measurements (see Experimental).…”

“…Another difference that may be useful to identify the 31 P signals of 1 and 10 is the value of 1 J PC , which is 154.0 Hz in 1 and 127.9 Hz in 10. This coupling constant is accessible from the 13 C satellites of the 31 P signals.…”

“…Much more complex are the { 1 H} 13 C spectra of cyclotriphosphazenes when a symmetry exists in the three phosphorus spin system, [18][19][20][21] as in the case of compounds 2, 4 and 6. They show second-order spectra from which, however, 31 P- 13 C coupling constants can be easily obtained. 21 These parameters are gathered in Table 1 with the 13 C chemical shifts.…”

“…The 1 H spectra of the cyclotriphosphazenes 2, 4 and 6 are theoretically much more complex than the 13 C spectra because 1 H is not a rare spin. 21 Nevertheless, with the help of homonuclear 1 H selective irradiations and { 31 P} 1 H spectra, all chemical shifts and coupling constants have been obtained and are collected in Table 2 with those of the corresponding phosphinic amides.…”