Nitriles pentene

Selective removal of allyl and allyloxycarbonyl protecting groups promoted by Pd/tppts catalytic systems (Equation 14) 43 536 540 Hydrocyanation of 1,3-butadiene and 3-pentene nitrile to adiponitrile (Equation 15) catalysed by Ni/tppts systems in the presence of reducing agents, such as NaBfL, or ZnCb49 541-542... 

Biphasic hydrocyanations were described as early as 1976 using Ni/TPPTS catalysts [165, 244 d]. Adipic dinitrile and methylglutaronitrile are obtained from 3-pentene nitrile/butadiene (see Section 2.5). 

It seems that the acidic cocaialysi is required to assure the rapid isomerization of pentene nitrile (equilibration step) and to promote the addition of 4-penteneniirile to the nuncunjugated double bond by assisting the formation of nickel hydride-type intermediates, since the Lewis acid acts as a cyanide acceptor (9). 

These last steps already contain the isomerization operation which proceed via the equilibration a and b in eq. (13). The reversibility of CN-carbon bond formation is also crucial. 3-PN itself is equilibrated with 4-pentene nitrile (4-PN, 44), so that in the last step mainly the isomeric straight-chain nitriles are available for hydrocyanation. 

In the first, a previously dried mixture of butadiene and hydrochloric acid is sent to the reactor with hydrogen cyanide entrained by nitrogen. The butadiene/HCN/N HC1 molar ratio is 1/1/1/0.2. Residence time remains less than one hour, at between 210 and 220 C, in the presence of copper chromite and magnesium as catalyst. A mixture of 3- and 4-pentene nitriles (88 per cent) and branched 3-methyl 1- and 2-butene nitriles (12 per cent) is obtained with virtually total once-througb conversion ... 

In the second step, the linear pentene nitriles are treated again with HCN in the presence of a catalyst, which is prepared in an auxiliary reactor, by causing a solution of nickel tetnrtolylphosphite to react in a mixture of m- and p-tritolylphosphites with a solution of SaCU lD tetrahydrofuran. The catalyst is prepared under nitrogen in the presence of 3- and 4-pentene nitriles. The reaction products are separated from the catalyst to be recycled by reverse osmosis through a suitable membrane. 

C7H10O3, Mx 142.15, has been identified in, e.g., coffee and melon. The tautomer mixture is a clear slightly yellowish liquid, bpQ02 tpa 82-83 °C, elf 1.137, nf 1.511 with sweet, caramel, fruity, bread-like odor. One commercially applied synthesis is the condensation of 2-pentene nitrile with ethyl lactate followed by oxidation of the intermediate 4-cyano-5-ethyl-2-methyldihydro-3(2/f)-furanone with monoperoxysulfate [189]. 

Other possible methods of the production of pyridine are the ring expansion of cyclopentadiene, and the cyclization of pentene nitrile, obtained as a by-product in the dimerization of acrylonitrile. 

If cis-2-pentene nitrile is used, the yield is even lower, since the necessary higher temperatures cause fragmentation, with the concurrent formation of gas and char. 

Table 16.3. Selectivities for formation of the linear dinitrile from nickel-catalyzed hydrocyanation of 4-pentene nitrile in the presence of a series of boron Lewis acids.

Moreover, the formation of enoxy-silanes via silylation of ketones127 by means of N-methyl-N-TMS-acetamide (1 72) in presence of sodium trimethylsilanolate (173) was reported in 1969 and since then, the use of silylating reagents in presence of a catalyst has found wide appreciation and growing utilization as shown in recent papers128-132 (Scheme 27). Diacetyl (181) can be converted by trifluoromethylsul-fonic acid-TMS-ester (182) into 2,3-bis(trimethylsiloxy)-l, 3-butadiene (7treatment with ethyl TMS acetate (7 5)/tetrakis(n-butyl)amine fluoride l-trimethylsiloxy-2-methyl-styrene (i<56)130. Cyclohexanone reacts with the combination dimethyl-TMS-amine (18 7)/p-toluenesulfonic acid to 1-trimethylsiloxy-l-cyclohexene (iSS)131. Similarly, acetylacetone plus phenyl-triethylsilyl-sulfide (189) afford 2-triethylsiloxy-2-pentene-4-one (790)132. ... 

The behavior of dibutyltin bis(dodecylmercaptide) on reaction with 4-chloro-2-pentene proved interesting (Figure 3). With only the two reactants in chlorobenzene, virtually no reaction took place up to 5 hours. However, the addition of dibutyltin dichloride resulted in a rapid reaction. Furthermore, the addition of a few milligrams of azobisisobutyro-nitrile eliminated any induction period. This latter consequence is not interpreted to result from a free radical stabilization mechanism, but it is presumed to be caused by free radical-catalyzed hydrogen chloride elimination, resulting (by neutralization with the stabilizer) in the formation... 

The last example consists of the synthesis of lycorane skeletons by an intramolecular cycloaddition of the azomethine ylide generated by the decarboxylation route (Section II,E). Thus, 3,4-(methylenedioxy)phenyIaceto-nitrile is deprotonated with LDA and then alkylated with 5-bromo-l-pentene... 

Zirconacyclopentenes 701 are obtained by the reaction of alkynes with Gp2ZrEt2, as shown in Scheme 170.526 The X-ray structure of 701 (R = R2 = Ph) indicates a single bond between the (3- and / -carbons of the zirconacyclo-pentene. The reaction of these zirconacyclopentenes with nitriles proceeds via (3,(3 -carbon-carbon bond cleavage of the zirconacyclopentenes to give the azazirconacyclopentadienes 702. Alkynes also react with diethyl zirconocene and electrophiles such as GlG02Et to give stereodefined ct, /3-unsaturated esters 703.527... 

The observed stereochemistry of the walk rearrangement corresponds to an inversion at the migrating carbon atom C-9 and fits the stereochemical requirements for an orbital symmetry controlled process (4). The different thermal behavior of 66a, 66b on the one hand and [2,7-(C6H5)2]-59, 59-l,2,7,8,9,9-c 6 on the other hand can be attributed to the stabilizing effect of the nitrile group on the transition state of the walk rearrangement similar to the case observed in the bicyclo[2.1.0] pentene system. 

A three-necked flask was charged with 5-chloro-l-iodo-l-pentene (1.8 g, 6.0 mmol) in THF (5 mL) and was cooled to — 100°C (liquid N2/ether bath), and n-BuLi (6.3 mmol, 1.6M in hexane) was added over 4 min. The resulting colorless solution was stirred at 0°C for 2min and cooled back to -78 °C. p-Toluenesulfonyl cyanide (0.90g, 5.0 mmol) in THF (5 mL) was added and the reaction mixture was warmed to room temperature and stirred for 3 h. After the usual workup and evaporation of the solvents, the crude residue obtained was purified by flash chromatography (hexane/ether, 10 1), yielding the unsaturated nitrile 10 (466 mg, 72% yield) as a clear oil (100% by GLC analysis and l3C NMR analysis). 

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