A-Acetoxyacrylonitriles

Similar effects were observed in the photocycloaddition of isoprene and a-acetoxyacrylonitrile(55b,56) but not in the cross-addition of the acrylonitrile and cyclopentadiene.[Pg.230]

Notice that the a-acetoxyacrylonitrile is in fact a "ketene equivalent" [30] in the Diels-Alder condensation with furan, since ketene itself undergoes [2 + 21-cycloadditions rather than [4 + 2] cycloadditions. 

The participation of diradical species in charge transfer reactions has been demonstrated in the most widely recognized example of donor-acceptor interaction—i.e., the Diels-Alder reaction. The two-step nature of this reaction has recently been proposed in the isolation of both four-and six-membered ring products in the thermal and photochemical reaction of butadiene and a-acetoxyacrylonitrile (14, 56). 

Diels-Alder dienophiles a-Acetoxyacrylonitrile. Acetylenedicarboxyhc acid. Acrolein (see 1-o-Nitrophenylbutadiene). Allyl alcohol (see Lithium). 1,4-Benzoquinone (see also 1,4-Naphthoquinone, preparation). /rans-l,2-Dibenzoylethylene. Di-(-butyl azodiformate. Dichloroketene. Dicyanoacetylene. Diethyl acetylenedicarboxylate. 1,4-Dihydronaphthalene-... 

Acetonitrile. CH3CN, b.p. 81.6° [1, 7, before a-Acetoxyacrylonitrile]. Aprotic. water-miscible Diels-Alder solvent (1, 239). Supplier of pure solvent. 1, 1110. For polara-graphic use. Moe1 notes that the main impurity is acrylonitrile, which differs from it in b.p. by only 4.2°, and recommends separation by distillation of the ternary and secondary azeotropes which the two liquids form with ethanol and with water. Ethanol (95%) is added to practical acetonitrile and the mixture is distilled through an H. Stedman column of 60-65 theoretical plates. The purified material is suitable also for U V spectroscopy. 

According to the activation volume data the Diels-Alder dimerization of 1,3-butadiene [39] and o-quinodimethane (Table 2.5, entries (3) and (4), respectively) fall into the same class of concerted processes as those discussed for 1 and 7, while the Diels-Alder dimerization of hexamethylbis(methylene)cyclopentane seems to occur in stepwise fashion. According to the activation volume data summarized in Table 2.6 only the Diels-Alder reaction of 1,3-butadiene with a-acetoxyacrylonitrile seems to proceed concertedly while all other Diels-Alder and homo-Diels-Alder adducts are probably formed in stepwise processes comparable to the corresponding competitive [2 + 2] cycloadditions. Stereochemical investigations of the chloroprene and 1,3-butadiene dimerization using specifically deuterated derivatives confirm the conclusions drawn from activation volume data. In the dimerization of ( )-l-deuteriochloroprene (17) the diastereomeric Diels-Alder adducts ISa-Dz and... 

This route is preferred for aromatic ketones (R =Ar). A less direct route involving treatment with dry hydrogen chloride, acetylation, and dehydration to an a-acetoxyacrylonitrile (4) is preferred for aliphatic ketones. The product can be converted into the carboxylic acid (3) or into an a-keto acid (5). Overall yields of the carboxylic acids by this route are in the range 50-75%. 

Levopimaric acid was converted into ketoacid 314 by the Diels-Alder addition of a-acetoxyacrylonitrile followed by basic work-up. Reduction of 314 with sodium borohydride afforded the crude product, which was treated with diazomethane and then acylated to give a mixture of acetoxyl-esters 315 and 316 in a 3 4 ratio. These compounds were separated by... 

A naked-sugar approach has been used (Scheme 12) to prepare the racemic allofuranuronosyl 6,1-lactone (36) from the Diels-Alder adduct of furan and a-acetoxyacrylonitrile.56... 

Bicyclo[2,2,2]octanes.—Extensions of the Diels-Alder reaction, still the most important route to this skeleton, concern the use of keten equivalents/ including the novel dienophiles vinyl boronate esters, the better established a-acetoxyacrylonitrile, and the highly regiospecific a-chloroacrylonitrile, the... 

A one-carbon homologation of aldehydes and ketones to carboxylic acids has been reported to involve the Horner-Emmons modification of the Wittig reaction using diethyl-/er/-butoxy(cyano)-methylphosphonate (EtO)2 P0CH(CN)0/-Bu to produce ethyl-/pr/-butoxyacrylonitriles. The /er/-butyl ether group is cleaved by zinc chloride in refluxing acetic anhydride, and the a-acetoxyacrylonitrile is converted to the acid by solvolysis. 

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