Aniline derivatives alkynylation

Jiang B, Si YG (2002) Zn(II)-mediated alkynylation-cyclization of o-trifluoroacetyl anilines one-pot synthesis of 4-trifluoromethyl-substituted quinoline derivatives. J Org Chem 67 9449-9451... 

Alkynes have been widely employed as the rr-component, with both A -nucleophiles (Scheme 6.46)" and 0-nucleophiles (Scheme 6.47) to give a variety of heterocycles. An application of particular importance has been in the synthesis of indoles 6.142 by the cyclization of o-alkynyl aniline 6.141 derivatives (Scheme 6.48)." The system may be extended to the synthesis of 3-acyl indoles 6.144 by the inclusion... 

Another efficient method to prepare chiral propargylamines 42 using a multicomponent process is by alkylation of in situ formed propargyl imines from alkynals 40 and o-phenoxy aniline (11c) by dialkylzinc derivatives 41 in the presence of a chiral ligand, for instance a dipeptide, and a Lewis acid salt, as depicted in Scheme 11.16 [48], Furthermore, the synthesis of A-aryl propargyl amines can be also performed by the alkynylation using dimethylzinc and terminal acetylenes of several aldehydes and o-methoxyaniline catalyzed by (l/ ,25)-A-bis(p-methoxybenzyl)norephedrine and phenylacetylene (52-93%, 79-97% ee) [49],... 

Cyclizations of alkynyl derivatives proved to be a synthetically convenient way to 2-(trifluoromethyl)quinolines. Indeed, the intramolecular cyclization of N-(a-trifluoromethyl)propargyl anilines 89 takes place with the gold(I) catalyst under extremely mild conditions to afford 2-trifluoromethylquinolines 90 (Scheme 36). The reaction mechanism has been suggested to involve cyclization and oxidation steps [57],... 

Indole synthesis starting from 2-unsubsituted anilines represents an atom-economical synthetic route that utilizes more readily available substrates. The Yamamoto group developed a method for nucleophilic introduction of alkynyl groups at the ortho position of the aniline moieties of A-phenylhydroxyamine derivatives 214 using aluminum acetylides 215 (Scheme 19.56) [101]. They applied this chemistry successfully to indole synthesis using Castro s conditions (Cul in DMF) to obtain indoles 217. 

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