| 20023958 |
Bennett J, Doyle RJ, Lee HY, Lu D, Salem G, Speldewinde DJ, Tifan M, Willis AC: Synthesis of 1,3-azaphosphol-2-ones. Dalton Trans. 2010 Jan 7;(1):256-64. Epub 2009 Nov 10.
Crystal and molecular structures of [SP-4-2]-dichlorobis (3-phenyl-1,3-dihydrobenzo [1,3] azaphosphol-2-one-P) pal ladium (II) and its chloro (methyl) platinum (II) analogue.. Reaction of secondary phosphine (+/-)-(2-aminophenyl) phenylphosphine, (+/-)-app, with PCl (5) in toluene gives the hydrochloride salt of the expected chlorophosphine (+/-)-(2-aminophenyl) chlorophenylphosphine, (+/-)-acpp.HCl, however, this is not the case with triphosgene. Rather the first example of a 1,3-azaphosphol-2-one is isolated, viz. (+/-)-3-phenyl-1,3-dihydrobenzo [1,3] azaphosphol-2-one, (+/-)-pbap. The hydrochloride salt (+/-)-acpp.HCl readily reacts with excess vinyl-, 2-methylphenyl- or 2-methoxyphenyl magnesium bromide to give the corresponding tertiary phosphines (+/-)-(2-H (2) NC (6) H (4)) PPhR (where R = CH=CH (2), 2-C (6) H (4) Me or 2-C (6) H (4) OMe). Hydrophosphination of the vinyl substituted tertiary phosphine with (+/-)-app in the presence of KOBu (t) provides a synthetic route to the elusive P (2) N (2) quadridentate ligand (R (P)*,R (P)*)- and (R (P)*,S (P)*)-(CH (2))(2)(PPhC (6) H (4) NH (2)-2)(2), albeit in low yield. The azaphospholone (+/-)-pbap can be readily deprotonated with KOBu (t) in thf and subsequently alkylated with methyl iodide or benzyl bromide to give the analogous N-methyl or N-benzyl derivatives. Alkylation with 1,3-dibromopropane gives the bis (azaphospholone) (R (P)*,R (P)*)- and (R (P)*,S (P)*)-1,3-bis [1-{3-phenyl-1,3-dihydrobenzo [1,3] azaphosphol-2-one}] propane. The latter and the N-methyl substituted azaphospholone can also be synthesised by the reaction of the corresponding secondary phosphine, viz. (R (P)*,R (P)*)- and (R (P)*,S (P)*)-(CH (2))(3)(NHC (6) H (4) PHPh-2)(2) and (+/-)-(2-methylaminophenyl) phenylphosphine, with triphosgene. All three azaphospholones react with [PtClMe (1,5-cyclooctadiene)] in thf to give complexes of the type cis-[PtClMeL (2)] in which ligand L is coordinated via the P atom of the azaphospholones. The ligand (+/-)-pbap has also been complexed to palladium (II) via the reaction with Li (2)[PdCl (4)] in methanol to give cis-[PdCl (2){(+/-)-pbap}(2)]. The structures of cis-[PtClMe{(+/-)-pbap}(2)] and cis-[PdCl (2){(+/-)-pbap}(2)] have been confirmed by X-ray analysis. |
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