The Fischer Indole synthesis in choline chloride.2 zinc chloride ionic liquid and the 1,3 arene-olefin cycloaddition reaction
We have utilised the copper(I) triflate catalysed intramolecular [2+2] photocycloaddition reaction to cyclise diene 53 to afford the exo product 54 in 60% yield (Chapter 2). (Fig. 15762A) Using choline chloride.2zinc chloride ionic liquid we have carried out a one pot Fischer Indole synthesis. Phenyl hydrazine 149 was reacted with ethylmethyliketone 298 to give 2,3-dimethyl-indole 273 as the only product in 80% yield. The product 273 was directly sublimed from the ionic liquid. 10 more examples of this reaction was carried out with direct sublimation of the product from the ionic liquid with yields between 48-90% (Chapter 3). (Fig. 15762B) A single diastereoisomer 517 was obtained from the 1,3 arene-olefin cycloaddition reaction of the substrate (S,S) (R,R) 508. This is arising from a prefulvene diradical 511. The structure of the product was confirmed by X-ray crystallography and the finding was confirmed by repeating the reaction with an analogous substrate (R,S), (S,R) 534 to give the single product 540 (Chapter 56). (Fig. 15762C).