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Browsing by Subject "Sandmeyer"

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    Acid-Catalyzed Condensation of Indole with Cyclic Ketones & Synthesis and Crystallographic Study of 2,6-Dihalobenzonitriles and Isocyanobenzenes
    (2017-06) Tritch, Kenneth
    I. As an extension of ongoing indole-ketone research, one-pot condensation reactions were performed between indole (1) and cyclic ketones with ring sizes n = 4–12 (2d–l) in the presence of boric, phosphoric, acetic, trifluoroacetic, hydrochloric, and toluene-4-sulfonic acids (Scheme 1). From fastest to slowest, the rate of condensation with indole was n = 6, 4, 5, 7, 12, 8, 11, 10, and 9. In addition to oligomerized indole, seven different types of products were isolated and identified. An eighth type of product was obtained from cyclododecanone, but it was not identified. The optimal catalyst for 2:1 condensation varied by ring size. CF3COOH or HCl were the best catalysts for one-pot preparation of all other products. II. Eleven 2,6-dihalobenzonitriles (204) and six corresponding isocyanobenzenes (209) were prepared (Scheme 2). To minimize radical-derived byproducts, it was important to perform cyanation in the presence of excess NaHCO3. Six nitriles and five isocyanides were analyzed by X-ray diffraction to study substituent effects on cyano-halo short contacts and the resulting ribbon or layer structures. All crystals exhibited such contacts. Polytypism of tribromo analogs 204ca and 209ca; and 2:1 anthracene co-crystals of cyano acids 204bc,cc were observed. Numbering. The introduction and discussion material is separated into two parts. Compound numbering begins at 1 and 201, for Part I and Part II, respectively. Main starting materials, intermediates, and products are given the lowest numbers. Entries in Part III and the appendices are given in numerical order, although Part III is also sorted by type of chemical reaction. Thus, several compounds in Part III are given more than one entry because they were prepared by more than one method.