Reaction iminoacylation

Yamamoto and Yamazaki 171) carried out reactions of Pt(PEt3)2CHjI and Pt(PPhMe2)(CH2CjH5)I with tert-butyl and cyclohexyl isocyanides. These reactions gave small yields of the ionic intermediate species, which readily reverted to the appropriate iminoacyl complexes. In reactions of analogous chloride complexes the intermediate species was not isolated. It is suggested on the basis of PMR data that these iminoacyl complexes are five-coordinate (see above). 

The migratory insertion reactions of the Ta-C functionalities in complexes 113-115 are presented in Scheme 22.9 In the reaction of 113-115 with both CO or Bu NC, the migration, under mild conditions (i.e., room temperature), of both alkyl or aryl groups to form r 2-ketones 116-118 and T 2-imino derivatives, 119-121, has been observed. Unlike the case of [Cp2M] or polyphenoxo derivatives of Ta, migration of the second alkyl or aryl group to the intermediate r 2-acyl or T 2-iminoacyl derivatives is very fast, which prevents the interception of the... 

Based on the established mechanism for titanium-catalyzed hydroamination, the authors propose a reversible reaction between a titanium imide complex and the alkyne to form metalloazacyclobutene 86, which in turn undergoes 1,1-insertion of the isonitrile into the Ti-C bond. The generated five-membered ring iminoacyl-amido complex 87 with the new C-C bond is protonated by the primary amine to afford the desired three-component coupling product, with regeneration of the catalytic imidotitanium species. Very recently, titanium-catalyzed carbon-carbon bond-forming reactions have been reviewed.122... 

Insertions of isocyanide into niobium-carbon bonds follow a path similar to that with vanadium, resulting in the formation of the 7]2-iminoacyl complexes, which can then be involved in further chemistry.175 176 The reaction of acetone with cyclopentadienyl complex 110 under a carbon monoxide atmosphere gives the if -acetone compound 111. Complex 111 subsequently undergoes either stepwise insertion of two isocyanides via 112 or double insertion of the isocyanide to give complex 113 (Scheme 48).177... 

A wide variety of five-membered zirconacydes 8 may be formed by the formal co-cycliza-tion of two 7i-components (3 and 6 alkene, alkyne, allene, imine, carbonyl, nitrile) on zir-conocene ( Cp2Zr ) (Scheme 3.2) [2,3,8]. The co-cydization takes place via the r 2-complex 5 of one of the components, which is usually formed by complexation of 3 with a zircono-cene equivalent (path a) ( Cp2Zr itself is probably too unstable to be a true intermediate) or by oxidation on the metal (cyclometallation/p-hydrogen elimination) (path b). Two additional routes to zirconocene r 2-complexes are by the reverse of the co-cyclization reaction (i. e. 8 reverting to 5 or 9 via 7), and by rearrangement of iminoacyl complexes (see Section... 

An equilibrium has been shown to exist between the enamine-ketimine form of the iminoacyl group (Scheme 4) by the addition of DzO, which effected deuteration of the methyl group, and by the addition of Me02C=CC02Me, which gave 78 (R = C6H4Me-/>). This cyclized product was characterized structurally. The intermediate 79 in this reaction was characterized by H NMR and by additions of HBF4 which formed 80 (409). 

The strongly basic character of the iminoacyl nitrogen has been demonstrated by protonations with NH4PF6 (4JO) and HBF4 (411) and alkylations with methyl iodide (384) to give metal -carbene complexes. Further examples include the formation of the secondary carbene [Ru C(CgH 3)-NHBu )(CNBu )5](PF6)2 from the reaction of (r], if-Ct H13)Ru... 

The interactions of compounds containing the oxime group with coordinated organonitriles are very important in template syntheses [384,413-416], These reactions take place as a nucleophilic addition and lead to the formation of complexes with unusual iminoacyl ligands. The iminoacylation reaction was studied in detail for various oximes and organonitriles, coordinated to PtCl4 [384,413-416]. Thus, the template transformation (3.192) of the discussed type in case of the oximes 744 takes place in acetonitrile or chloroform and yields complexes of the type 745 [413a] ... 

The use of the permethyltitanocene template 94 (Scheme 14) allows for the isolation of the intermediate iminoacyl complex 95, which was not observed in reactions using the substituted bis(indenyl)titanocene. 

The nitrene 28 is not produced from the azide precursor, but from heterocycles via photolysis and thermolysis as shown in Sch. 11 [20]. Iminoacyl nitrenes react intramolecularly giving benzimidazoles with good yields (Sch. 11), and, dependending on the precursor used and the reaction conditions, varying amounts of carbodiimides are obtained. The reactivity of the acyl nitrenes is influenced by the substituent connected to the acyl group (see Sch. 10), however all acyl nitrenes are quite reactive and therefore rather unselective. Apart from cycloaddition reactions with Tt-bonds, insertion reactions into a-bonds, additions to lone pair electrons of... 

The related ) -immoacyl complexes (124) are known ()] -C=N). These may be prepared by reaction of [Fe(CO)2(PMe3)2(Me)I] with t-butyl isocyanide, through an equilibrium with ] -iminoacyl complex (125). The equilibration is catalyzed by halide ion, NOs, and C104, but not by BF4, PFe , or BPlu consequently, the pure compounds are isolated by precipitating the BPli4 salt from the mixture. The mechanistic details of the equilibrium have been investigated in detail. ... 

Treatment of Cp ( ) -C5Me4CH2)Ti with PbCb gives Cp (jj -C5Me4CH2)TiCl, which reacts with C=N(2,6-Me2C6H3) to give the ) -iminoacyl complex (36). Reaction of iminoacyl (28) with a second equivalent of isonitrile gives (37). ... 

Neutral and cationic homoleptic (see Homoleptic Compound) tnngsten-isocyanide complexes W(CNR)6 and [W(CNR)y] + (R = alkyl, aryl) are known, and W(CO)e (CNR) (n=l-3) complexes may be prepared from W(CO)6 and excess isocyanide in the presence of catalytic amounts of C0CI2 or PdO. Iso-cyanides are isoelecfronic with CO and also insert into the W-R bonds of alkyl complexes (see Alkyl Complexes). For instance, the alkyl-nitrosyl complexes Cp W(NO)(X)(CH2Bfr) (X = NHBfr, OBfr) react with CNBu to afford -iminoacyl complexes, and the isocyanide complexes, Cp W(CO)2(Me)(CNR) (10, R = alkyl), rearrange to afford either -iminoacyl Cp W(CO)2( -MeCNR)(ll) or ij -l-azaallyl Cp W(CO)2( -CH2CHNR) (12) derivatives, depending upon the reaction conditions (equation 4). ... 

Decarbonylation at room temperature does not occur, presumably beause the intermediate alkyl would be part of a strained four-membered-ring chelate. Related iminoacyl rhodium hydrides, 2, are prepared from the reaction of the readily available 2-aminopyridyl aminals or 2-amino-3-methylpyridyl aldimines and RhCl(PPh3)3 ... 

The Tj -iminoacyl complexes 354 react with CO to give the corresponding amidoenolato complexes 355 . Similarly, the reaction between 356 and CO gives 357 °. 

The rearrangement of a tungsten carbonyl-complexed 7-phosphanorbomadiene to its 7-phosphatricyclo[3.2.0 ]hept-2-ene complex has been analysed by ab initio MO calculations, and it has been shown that the reactions of molybdenum and tungsten metallates of the type [CpM(CO)2CNR] with methyl iodide yield methyl complexes of the composition [CpM(CO)2(CNR)], which subsequently rearrange to / -iminoacyls and / -l-azaallyls depending on the nature of the metal, the isocyanide R substituent, and the solvent used. ... 

Interestingly, Bochmann el at. have characterized several Ti(IV) RNC adducts which are rare examples of cP metal isocyanide complexes (39). The reaction of (C5H5)2Ti(CH3)(CH3CN)+ with RNC (R = Bu, SiMe3) yields the iminoacyl complexes (C5H5)2Ti(/ -C(Me)=NR (CNR)+ via insertion of and trapping by RNC. The BuNC complex Cp 2Ti(CH3)(CN Bu)+ is observed as an intermediate in the analogous... 

---