Substitution cine-type

Unactivated aryl halides can be converted to amines by the use of NaNH2, NaNHR, or NaNR2. With these reagents, the benzyne mechanism generally operates, so cine substitution is often found. Ring closure has been effected by this type of reaction,for example. 

In troponoid chemistry cine substitution occurs frequently. In many cases it can be explained by the intermediacy of dehydrotropolone species ( tro-polonyne ) as trapped, for example, by azides (Section II,A,3,h Scheme 34). An alternative mechanism may be a Michael-type addition followed by elimination. The intramolecular cyclizations depicted in Scheme 47 very likely proceed via Michael-type attack (73CRV293, p.351). 

Arasabenzene, with chromium, 5, 339 Arcyriacyanin A, via Heck couplings, 11, 320 Arduengo-type carbenes with titanium(IV), 4, 366 with vanadium, 5, 10 (Arene(chromium carbonyls analytical applications, 5, 261 benzyl cation stabilization, 5, 245 biomedical applications, 5, 260 chiral, as asymmetric catalysis ligands, 5, 241 chromatographic separation, 5, 239 cine and tele nucleophilic substitutions, 5, 236 kinetic and mechanistic studies, 5, 257 liquid crystalline behaviour, 5, 262 lithiations and electrophile reactions, 5, 236 as main polymer chain unit, 5, 251 mass spectroscopic studies, 5, 256 miscellaneous compounds, 5, 258 NMR studies, 5, 255 palladium coupling, 5, 239 polymer-bound complexes, 5, 250 spectroscopic studies, 5, 256 X-ray data analysis, 5, 257... 

Cross-coupling reactions with vinylboronic acids can yield either the normal product (ipso-substitution of boron) or a regioisomer formed via a Heck-type reaction (cine-substitution Scheme 8.17) [135]. Formation of the normal product (1-phenylhexene in Scheme 8.17) requires a base capable of binding to the boronic acid, thereby increasing the nucleophilicity of the boron-bound carbon atom (typically ROM, MOH, M2C03, M3P04, where M= alkali metal [136]). Products of cine-substitution result when tertiary amines are used as bases, i.e. under Heck-type reaction conditions. 

The 2-methyl-4/3,5/3-epoxy-3-ketone (244) reacts with methoxide ion to give the three products (245)—(247).208 A Favorskii-type rearrangement is clearly responsible for producing the A-nor-lactone (245), and is considered also to account for the other two products. The 2-methoxy-2-methyl-4-en-3-one (246), however, could possibly result from direct attack of methoxide ion on the A2-enol derivative of the epoxy-ketone (cine substitution), followed by elimination of a 5/3-hydroxy-group to give the a/3-unsaturated ketone. The occurrence of Favorskii rearrangement in the 2-methylated compound (244) contrasts with a simple nucleophilic opening of the unsubstituted 4/3,5/3-epoxy-3-ketone this is one of several recent examples in which an a-substituent favours Favorskii rather than alternative reactions.208... 

NaNHR, or NaNR2. Lithium dialkylamides also react with aryl halides to give the A-arylamine. With these reagents, the benzyne mechanism generally operates, so cine substitution is often found. The reaction of an amine, an aryl halide, and potassium tert-butoxide generates the A -aryl amine. A -Arylation was accomplished with butyllithium and a secondary amine using Ni/C-diphenylpho-sphinoferrocene (dppf). Ring closure has been effected by this type of reaction, as in the conversion of 16 to the tetrahydroquinoline. 

PROBLEM 14.73 Years before J. D. Roberts classic labeling experiment (p. 681), it was known that nucleophilic aromatic substitution occasionally resulted in what was termed cine (from the Greek kinema meaning movement ) substitution. In this type of substitution reaction, the nucleophile becomes attached to the carbon adjacent to the carbon bearing the leaving group. Here are two examples of this kind of substitution ... 

The examples of nucleophilic substitution discussed in Sect. 3.4 belong to the ipso-type [185]. In c/ne-substitution, the leaving group departs from the position adjacent to the nucleophile addition site, and in teZe-substitution, the leaving group departs from a more remote position on the ring or even from a side-chain [159]. cine- and feZe-substitutions of various nonaromatic, aromatic and heteroaromatic compounds, including thiophene, have been reviewed [185]. 

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