Synthesis and structures of cis- and trans-bis(allenyl)cylclodiphosph(V)azanes and a bis(allyl)cyclodiphosph(V)azane

The bis-(allenyl)phosphoramidates cis-[(H2CCCH)(O)P(μ-N-t-Bu)]2 (9), cis- and trans-[(Me2CCCH)(O)P(μ-N-t-Bu)]2 (10a,b) and cis- and trans-[((Me)(Et)CCCH)(O)P(μ-N-t-Bu)]2 (11a,b) based on a cyclodiphosph(V)azane skeleton have been synthesized by treating cis-[ClP(μ-N-t-Bu)]2 (1) with the respective propargylic alcohol in the presence of triethylamine. The Baylis–Hillman adduct PhCH(OH)C(CO2Me)CH2 also reacts with 1 to lead to the bis-(allyl)phosphoramidate cis-[((Ph)HCC(CO2Me)–CH2)(O)P(μ-N-t-Bu)]2 · H2O (13 · H2O). In this case, a 31P NMR study shows that yet another P(V) compound, tentatively assigned the trans-structure, was initially formed. Preliminary calculations suggest that the cis-isomer 10a is slightly more stable than the trans-isomer 10b in the gas phase. The structures of 9, 10a,b and 13 · H2O are confirmed by X-ray crystallography.

From the reaction of cis-[ClP(μ-N-t-Bu)]2 (1) with HOC(R)(Me)CCH/Et3N, both cis- and trans-isomers of bis-(allenyl)phosphoramidates [((Me)RCCCH)(O)P(μ-N-t-Bu)]2 [R = Me or Et] have been synthesized. No P(III) intermediate was detected. In contrast, only the cis-isomer of (i) allenyl compound [(H2CCCH)(O)P(μ-N-t-Bu)]2 or (ii) allyl compound [((Ph)HCC(CO2Me)–CH2)(O)P(μ-N-t-Bu)]2 is obtained almost exclusively by reacting 1 with HOCH2CCH or PhCH(OH)C(CO2Me)CH2, respectively.Figure optionsDownload as PowerPoint slide