Nitriles reagents

Nitrile Reagent G Yield (%) Nitrile Reagent H Yield (%)... 

Nitriles react with (butadiene)zirconocenes in similar ways however, some important details of the reaction course are different in these cases. A variety of aryl-, hetaryl-, or alkylcyanides add cleanly to the [(butadiene) ZrCp2] reagent. It is likely that 92 is the initial CC-coupling product. Under typical reaction conditions this is not stable but rapidly undergoes a tautomerization reaction to yield the isomer 93. This can rapidly react further with a second equivalent of the nitrile reagent to... 

An interesting application of self-condensation of the intermediate nitrilimine already incorporating the nitrile reagent (67JOC1871) is useful for the preparation of symmetrical 3,5-disubstituted 1,2,4-triazoles such as (293 Scheme 130) but the method illustrated in Scheme 129 is better for the preparation of unsymmetrical analogues (294). 

Generally, iodine azide adds to an alkene by an ionic pathway, yielding a tram addition product however, in a few cases nitrile reagents compete successfully with azide ion in attacking the iodonium intermediate. Thus, ci-pinene was converted into tetrazole (125) in a one-pot reaction in near quantitative yield (Scheme 59).This type of process is far from general. 

See page 1809, Section 6 for analogous conjugate additions to a,/ -unsaturated, esters and nitriles. Reagent(s)... 

This was taken a step further with the synthesis of pyrrole units - pyrrolecarboxtildehydes - by using appropriate nitrile reagents [42]. This represented a competing method with the classic Paal-Knorr pyrrole synthesis. The scope was broad and the yields good. 

Recent advances in the stereoselective olefination of phosphorus-stabilized carbon nucleophiles have been reviewed. Applications of the Horner-Wadsworth-Emmons reaction to the synthesis of natural products have been highligted. A highly Z-selective synthesis of a, -unsaturated nitriles using the Homer-Wadsworth-Emmons reaction has been reported this involves a new nitrile reagent, (o-t-BuC6H40)2P(0)CH2CN, which reacts with various types of aldehydes with 86 to >99% Z selectivity. 

Dehydration of Aldoximes to Nitriles. Reagent (1) has been shown to be excellent for the dehydration of aldoximes of both aromatic and aliphatic aldehydes. This is accomplished by reacting the aldoxime with (1) in dioxane at 20 °C for 20 h (eq 7). ... 

All manipulations were carried out using standard vacuum line and dry box techniques under inert atmospheres or vacuum. Solvents were dried over molecular sieves and stored under nitrogen. Diisobutylaluminum hydride and the nitrile reagents were used as received. CAUTION Diisobutylaluminum hydride (DIBAL-H) is very moisture sensitive in dilute solutions and pyrophoric when neat The alkylaluminum imine complexes were prepared by literature methods (41). Thermal polymerization of the aluminum imine complexes was accomplished as previously reported (42-45). Controlled headspace analysis was conducted by holding seal ... 

Nitriles also react w ith Grignard reagents to give ketones, which arise from the hydrolysing action of the dilute sulphuric acid on the intermediate addition product. Acid amides beha e similarly. 

Strictly speaking the alkyl halides are esters of the halogen acids, but since they enter into many reactions (t.g., formation of Grignard reagents, reaction with potassium cyanide to yield nitriles, etc.) which cannot be brought about by the other eaters, the alkyl halides are usually distinguished from the esters of the other inorganic acids. The preparation of a number of these is described below. 

To explain the experimentally observed high reactivity of HCN and alkyl nitriles under snperacidic condition, Shndo found that in the Gat-terman and Houben-Hoesch reactions, diprotonated HCN (or nitriles) are involved as the de facto reagents (HC N H2, RC N H2). 

Ketones can be converted to nitriles with an additional carbon atom with the aid of the TosMIC reagent (J.R. BuU, 1975 O.H. Oldenziel, 1973). 

The conversion of carboxylic acid derivatives (halides, esters and lactones, tertiary amides and lactams, nitriles) into aldehydes can be achieved with bulky aluminum hydrides (e.g. DIBAL = diisobutylaluminum hydride, lithium trialkoxyalanates). Simple addition of three equivalents of an alcohol to LiAlH, in THF solution produces those deactivated and selective reagents, e.g. lithium triisopropoxyalanate, LiAlH(OPr )j (J. Malek, 1972). 

Allylalion of the alkoxymalonitrile 231 followed by hydrolysis affords acyl cyanide, which is converted into the amide 232. Hence the reagent 231 can be used as an acyl anion equivalent[144]. Methoxy(phenylthio)acetonitrile is allylated with allylic carbonates or vinyloxiranes. After allylation. they are converted into esters or lactones. The intramolecular version using 233 has been applied to the synthesis of the macrolide 234[37]. The /i,7-unsaturated nitrile 235 is prepared by the reaction of allylic carbonate with trimethylsilyl cyanide[145]. 

The carbon-nitrogen triple bond of nitriles is much less reactive toward nucleophilic addition than is the carbon-oxygen double bond of aldehydes and ketones Strongly basic nucleophiles such as Gngnard reagents however do react with nitriles in a reaction that IS of synthetic value... 

The mine formed by nucleophilic addition of the Gngnard reagent to the nitrile is nor mally not isolated but is hydrolyzed directly to a ketone The overall sequence is used as a means of preparing ketones... 

Section 20 20 Nitriles are useful starting materials for the preparation of ketones by reaction with Grignard reagents... 

Among the methods for preparing carboxylic acids carboxylation of a Grignard reagent and preparation and hydrolysis of a nitrile convert RBr to RCO2H The malonic ester synthesis converts RBr to RCH2CO2H... 

Reactions that employ copper(I) salts as reagents for replacement of nitrogen m diazo mum salts are called Sandmeyer reactions The Sandmeyer reaction using copper(I) cyanide is a good method for the preparation of aromatic nitriles... 

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