17437-50-2Relevant articles and documents
Synthesis, structure, and reactions of (acylimino)triaryl-λ5-bismuthanes: First comparative study of the (acylimino)pnictorane series
Matano,Nomura,Suzuki,Shiro,Nakano
, p. 10954 - 10965 (2007/10/03)
The synthesis, structure, and reactions of (acylimino)triaryl-λ5-bismuthanes and a comparative study of the structure and reactivity of a series of (acylimino)pnictoranes are reported. Treatment of ortho-substituted triarylbismuth dichlorides 1 (Ar3BiCl2; Ar = 2-MeC6H4, 2-MeOC6H4, 2,4,6-Me3C6H2) with amides 2 (H2-NCOR; R = CF3, CCl3, 3,5-(CF3)2C6H3) in the presence of 2.2 equiv of KO-t-Bu in dichloromethane afforded (acylimino)triaryl-λ5-bismuthanes 3 (Ar3Bi=NCOR) in yields of 77-96%. The ortho-substituted aryl ligands and the electron-withdrawing N-substituents afford kinetic and thermodynamic stabilization, respectively, to the reactive Bi=N bond. The structures and properties of a series of (acylimino)pnictoranes (Ar3M=NCOR and H3M=NCOCF3; M = P, As, Sb, Bi) are compared by IR and 13C and 15N NMR, X-ray crystallography, and ab initio molecular orbital calculations. It was found that the contribution of the M+-N=C-O- canonical form becomes more prominent and the single-bond character of the M=N bond increases progressively as the pnictogen atom becomes heavier. The Bi=N bond of (acylimino)-λ5-bismuthanes 3 possesses a highly polarized single-bond character, probably due to the differences in orbital size and electronegativity between the bismuth and nitrogen atoms. Thermal decomposition of (aroylimino)triaryl-λ5-bismuthane 3f (o-Tol3Bi=NCOAr; Ar = 3,5-(CF3)2C6H3) produces a gel in dry conditions or aniline 12 (ArNH2) in slightly wet conditions with a good recovery of tris(2-methylphenyl)bismuthane (4a). It is likely that the aryl isocyanate 13 (ArNCO) is produced during the thermolysis via a concerted C → N migration of the Ar group with an elimination of the triarylbismuthonio group as bismuthane 4a. (Acylimino)triaryl-λ5-bismuthanes 3 oxidize 1,1,2,2-tetraphenylethanediol, benzenethiol, methanol, and ethanol to benzophenone, diphenyl disulfide, methyl formate, and acetaldehyde, respectively, in two different reaction pathways depending on the structure of the substrates. Compound 3d (o-Tol3Bi=NCOCCl3) transfers the nitrenoid moiety to triphenylphosphane, triphenylarsane, and tris(2-methylphenyl)stibane to give the corresponding (acylimino)pnictoranes (Ar3M=NCOCl3; M = P, As, Sb) and 4a, suggesting that 3d is thermodynamically much less stable than their lighter pnictogen counterparts. The copper-catalyzed decomposition of 3 (o-Tol3Bi=NCOR) afforded N-acyl-o-toluidines 18 (o-TolNHCOR) via a Bi → N migration of the tolyl group. The observed reactivities of (acylimino)triaryl-λ5-bismuthanes 3 demonstrate a good leaving ability of the bismuthonio group.
Synthesis of N-Acyl-, N-Sulfonyl-, and N-Phosphinylphospha-λ5-azenes by a Redox-Condensation Reaction Using Amides, Triphenylphosphine, and Diethyl Azodicarboxylate
Bittner, Shmuel,Assaf, Yonit,Krief, Penina,Pomerantz, Martin,Ziemnicka, Barbara T.,Smith, Christina G.
, p. 1712 - 1718 (2007/10/02)
The reaction of phosphines and amides with diethyl azodicarboxylate (DAD) produced phospha-λ5-azenes.Thus aromatic amides and those aliphathic amides with electron-withdrawing substituents gave N-acyl-P,P,P-triphenylphospha-λ5-azenes (5) when triphenylphosphine (TPP) was employed.Both aryl- and alkylsulfonamides reacted with TPP and DAD to produce the N-sulfonylphospha-λ5-azenes (9).Diphenylphosphinamide (10) and ethyl carbamate (12) also produced the respective phosphazenes (11 and 13) with TPP and DAD.Secondary carboxamides and sulfonamides did not react with TPP and DAD.The reaction of triethyl phosphite with sulfonamides in the presence of DAD produced the phosphorimidates (20) in an analogous reaction, along with the corresponding N,N-diethylsulfonamides and the deethylated adduct of triethyl phosphite and DAD (23).Triethyl phosphite-DAD failed, however, to give a phosphorimidate with carboxamides but gave, instead, the rearranged adduct of DAD and triethyl phosphite (19).Tris(dimethylamino)phosphine reacted with sulfonamides and DAD but the products were the corresponding ethyl N-sulfonylcarbamates (26) rather than the phosphazenes.Tris(dimethylamino)phosphine reacted with azodicarbonamide (a molecule which contains both the azo and carboxamide groups) with the production of N,N-dimethylurea, again without formation of the phosphazene.Finally, the reaction of triphenylarsine with benzenesulfonamide and DAD produced N-(phenylsulfonyl)triphenylarsa-λ5-azene (30) but triphenylstibene with DAD and benzenesulfonamide only gave triphenylstibene oxide.Mechanistic possibilities for these reactions are also discussed.
