Alkynyl cyanides, reactions with

An S-acetylated 2-aminothiol was reacted with 2-chloroacyl chlorides (Equation 85) <1989JPS937>. The reactions of 2-aminoethanethiol with 2,3-butanedione <1998JFA2278>, alkynyl cyanide 279 <1993TL5681>, and cyclic hemiacylal 281 <1992FI(34)2131> are shown in Scheme 59. Mechanisms for the formation of products 277, 278, and 280 were suggested, but not however for the unexpected product from 281. 

Reaction with an amine, AIBN, CO and a tetraalkyltin catalyst also leads to an amide.Benzylic and allylic halides were converted to carboxylic acids electroca-talytically, with CO and a cobalt imine complex. Vinylic halides were similarly converted with CO and nickel cyanide, under phase-transfer conditions.Allylic (9-phosphates were converted to allylic amides with CO and ClTi=NTMS, in the presence of a palladium catalyst. Terminal alkynes were converted to the alkynyl ester using CO, PdBr2, CuBr2 in methanol and sodium bicarbonate. ... 

The scope of nitriles for the carbocyanation reaction of alkynes can be expanded by cooperative nickel/Lewis acid catalysis. Alkenyl [80, 81] and alkynyl cyanides [83, 84] also participate in the addition reaction to give highly conjugated nitrile products by nickel/BPh3 catalysis (Scheme 27). The use of aluminum-based Lewis acids causes isomerization of the double bond of alkenylcyanation products, whereas alkynylcyanation is sluggish with the aluminum reagents. 

Cyanogen iodide reacts with terminal alkynes forming alkynyl cyanides. The reaction is catalysed by CuOTf and 2,2,6,6-tetramethylpiperidine (TEMP) in yields between 45 and 78%. The first step in the reaction occurs when the alkyne reacts with I-CN and TEMP forming an alkynyl iodide. The product is formed when the alkynyl iodide reacts with a complex formed from CuOTf, TEMP, and a second molecule of I-CN. Many groups are tolerated in the terminal alkyne. 

The nickel-catalyzed carbocyanation of alkyne 74 with alkynyl cyanide 76 was accomplished using BPhg as the cocatalyst to produce 77. On the other hand, [2+2+2] trimerization of 74 predominated to form 78 when the reaction was conducted in the absence of BPhg (Scheme 6.15) [50]. An alkynylnickel complex formed via oxidative addition of BPhg-activated alkynyl cyanide has been identified. 

It is well known that MPV type hydride transfer proceeds via six membered transition state with concerted mechanism. As shown in Figure 6.3, similar alkynyl transfer reaction and cyanide transfer reaction have also been reported. 

Ooi and Maruoka found that aluminum alkoxide (83) prepared from aluminum complex (82) and tertiary propargyl alcohol reacts with highly electrophilic aldehydes, such as chloral and pentafluorobenzaldehyde, to give alkynyl transfer products in good yield (Scheme 6.65) [84]. Bisphenol structure of ligands on aluminum center is the most important feature to obtain the alkynylated products, and thus, in reactions with (84) or (85) instead of (83) dramatical decrease in the yield of alkynyl product was observed. Same group also reported that cyanide transfer reaction with acetone cyanohydrin as a cyanide donor catalyzed by complex (82) [84]. 

Reduction by Alkali Metals. This was the first reduction method successfully used it is particularly useful for reducing in liquid ammonia cyanides ( ), alkynyls (f 4 ), ammines (193) and ethylendiammines (192). The same reaction on phosphine compounds gives low yields because the reagents are insoluble in liquid ammonia (45). The zero valent nickel compounds with phosphites are obtained in good yield with the potassium graphite compound KCs (110). 

As with cyanide, Sn2 reactions of alkyne anions can be done with substrates other than halides or sulfonate esters. Epoxides are opened by acetylides at the less sterically hindered carbon to give an alkynyl alcohol. A synthetic example is the reaction of epoxide 38 with the indicated lithium alkyne anion gave an 85% yield of 39, an intermediate in the Sinha et al. synthesis of squamotacin.49... 

A-tosylhydrazones (equation 2) [52]. The reaction can also be executed in one pot from arylhalide, aldehyde, and tosyl hydrazine. A novel 2-arylindole synthesis that was discovered by Rashinkar entails the Pd-catalyzed reaction of o-nitrobenzyl cyanides with arylboronic acids (equation 3) [53]. Tobisu and Chatani accomplished the direct Pd-catalyzed alkynylation of anihdes leading to indoles (equation 4) [54], Lee and colleagues induced nitriles into becoming indole-3-carboxylates through the Blaise reaction (equation 5) [55]. 

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