Diimides synthesis

Presently only the direct nitridation and the diimide synthesis are of commercial importance the industrial production by gas phase reaction was given up recently. 

The diimide synthesis takes place at the interface between liquid ammonia and the organic solvent in which the SiCl4 is dissolved. The product must be washed and calcined to remove the NH4Cl. At high temperatures (1300-1500 °C) the crystallisation to an a-rich powder takes place [220]. Temperatures above 1500 °C cause an increase of /I and grain size [221]. A very fine /1-rich powder can be obtained, when the crystallisation of an amorphous Si3N4 powder takes place at 1300-1450 °C in presence of an oxide nitride liquid in which the amorphous phase can be dissolved and reprecipitated mainly as /I [219]. 

There are three more possibilities for the powder production by the diimide synthesis [206]. Beside the reaction at interfaces of two liquids the formation of the diimide can be realised by... 

Direct nitridation Diimide synthesis Plasma chemical synthesis... 

Carbothermal nitridation of silica, including rice huUs Diimide synthesis Vapor-phase synthesis Plasmachemical synthesis Laser-induced reactions Pyrolysis of organosilicon compounds... 

J-L, Han B, Jiang K, Du W, Chen Y-C (2009b) Organocatalytic enantioselective hetero-Diels-Alder reaction of aldehydes and o-benzoquinone diimide synthesis of optically active hydroquinoxalines. Bioorg Med Chem Lett 19(14) 3952-3954. doi 10.1016/j.bmcl. 2009.03.013... 

Mullen and co-workers extended the synthesis of perylene discotics to various other core-enlarged perylene dyes, such as terrylene and quaterrylene diimides [158]. An example of quaterrylene diimides synthesis is shown in Scheme 4.24. 

Thionyl imide, HNSO, is a thermally unstable gas, which polymerizes readily. It can be prepared by the reaction of thionyl chloride with ammonia in the gas phase. Organic derivatives RNSO have higher thermal stability, especially when R = Ar. The typical synthesis involves the reaction of a primary amine or, preferably, a silylated amine with thionyl chloride. A recent example is the preparation of FcNSO (Fc = ferrocenyl) shown in Eq. 9.8. In common with other thionylimines, FcNSO readily undergoes SO2 elimination in the presence of a base, e.g., KO Bu, to give the corresponding sulfur diimide FcNSNFc. 

Perylenes (70) are diimides of perylene-3,4,9,10-tetracarboxylic acid, and may be prepared by reaction of the bis-anhydride of this acid, 89 (1 mol) with the appropriate amine (2 mol) in a high-boiling solvent as illustrated in Scheme 4.11. The synthesis of perinones 71 and 72 involves condensation of naphthalene-1,4,5,8-tetracarboxylic acid with benzene-1,2-diamine in refluxing acetic acid. This affords a mixture of the two isomers, which may be separated by a variety of methods, generally involving their differential solubility in acids and alkalis. 

It was envisioned that hydrindanone 83 and cyclopentene 85 could be used as intermediates in the synthesis of e f-retigeranic acid A (1) and e f-retigeranic acid B (2), respectively. To prepare the building block 90, cyclopentene 85 was reduced with diimide (93 %) in order to prevent isomerization and subsequently deprotected with PPTS to yield hydrindanone 90 (quant.), which could provide access to <77/-retigeranic acid B (2) (Scheme 10.7). Hydrindanone 83 was reduced via an enol triflate and then subjected to Pd-catalyzed reduction to provide cyclopentene 91 (87 % from 83). Upon hydrogenation of 91 with Pd/C and cleavage of the acetal with iodine, protected hydrindanone 92 (95 % from 91) was obtained. The deprotection of 92 provided ent-60, whose enantiomer was used in previous syntheses of retigeranic acid A (1) by Corey [14] and Hudlicky [46, 47]. 

Polymer-bound 1-hydroxybenzotriazole 1008 reacts with carboxylic acids in the presence of 1,3-diisopropylcarbo-diimide (1,3-DIC) and DMAP to produce esters 1009. Treated with hydroxylamine, esters 1009 are converted to hydroxamic acids 1010 (Scheme 167) <20030BC850>. Starting 1-hydroxybenzotriazole 1008 is recycled in the process and can be used for other syntheses. This method is well suited for automated synthesis of a library of hydroxamic acids. In similar applications of polymer-supported 1-hydroxybenzotriazole 1008, a wide variety of amides is synthesized <1997JOC2594, 2002JC0576>. 

Janetka and Rich (78) have utilized the considerable stability of ruthenium-77-arene systems in the synthesis of cyclic tripeptides as analogs of the protease inhibitor K-13 (cf. 34, Scheme 28). Their approach involves the construction of linear tripeptide complexes (35) using diimide/HOBt coupling of [Ru(Cp)(Boc-p-Cl-PheOH)]PF6 (Cp = 775-C5H5) with the appropriate dipeptide ester. Cyclization of 35 affords the biphenyl ether 36, which on photolysis (350 nm) gives 34. 

A different route proceeds by alkali fusion of the corrspondingly substituted naphthalic acid imide. This pathway parallels the synthesis of perylene tetracarboxylic acid diimide 70 (Sec. 3.4.1.1). The method is particularly suited to aliphatic amines. 

Symmetrical anhydrides are stable enough to be isolated but not stable enough to be stored for future use. They can be purified by repeated crystallization or by washing a solution of the anhydride that has been obtained using a soluble carbo-diimide with aqueous solutions (see Section 1.16). The use of symmetrical anhydrides allows for synthesis of a peptide with less possibility of generation of side products. The anhydrides are particularly effective for acylating secondary amines (see Section 8.15).9 11... 

Diazadiphosphetidines nomenclature of, 14 3 synthesis of, 14 71 Diazaphosphetidinone, 14 85 1,6-Diazatriptycene, 33 1-2 Diazene, see also Diimide complexes, osmium, 37 260 ligand, 27 227-235 complexes, 27 230-235, 256-257 free state, 27 227-230 in preparation of dinitrogen complexes, 27 222, 232... 

The first structural characterization of a tellurium diimide RNTe(p-N Bu)2TeNR (R = PPh2NSiMe3) was reported in 1994. Subsequently, the synthesis of the symmetric derivative, R = Bu, was achieved by the reaction of Li[HN Bu] with TeClq in a 4 1 molar ratio in toluene. Several LiCl-containing byproducts are also obtained in this solvent. In THF, however, the tellurium diimide, BuN-Te(p-N Bu)2TeN Bu, is obtained in 90% yield and is readily purified." Unlike sulfur or selenium diimides, the tellurium diimides are dimeric and form either cis or... 

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