Study On Domino Reaction Of 2-(2-Alkynylarylidene)-1,3-Dicarbonyl Compounds

Benzopolycycles can be found in many natural occurring products, commercially important pharmaceuticals, argricultures, food industries, functional materials and dynes. They are also considered as building blocks for the construction of numerous natural and non-natural compouns. Many chemists focus their research interests on developing new methodologies for the synthesis and transformation of this class of compounds.The selective synthesis of different products from the same starting materials by simple subtle modification of structure or reaction conditions is an attractive challenge for chemists. This dissertation reports the selective reactions of 2-(2-alkynylarylidene)-1,3-dicarbonyl compounds which can be formed from o-alkynylbenzaldehyde and 1,3-dicarbonyl compounds. Several types of polycycles can be synthesized from the reaction of 2-(2-alkynylarylidene)-1,3-dicarbonyl with the simple subtle modification of structure or reaction conditions.In the first part, we have developed an efficient Br(?)nsted acid-and Lewis acid-catalyzed benzannulation of 2-(2-alkynylarylidene)-1,3-dicarbonyl compounds to afford polysubstituted naphthalenes and benzo[a]fluorenols. Furthermore, the product selectivity could be tuned by subtle choice of the catalyst. An unprecedented process between alkynes and ketones was explored. On the basis of those experimental data, mechanism of this transformation was discussed.In the second part, we have developed a Lewis acid-catalyzed regiodivergent tandem cationic cyclization/ring expansion terminated by pinacol rearrangement selectively affording naphthalen-2(1H)-ones or naphthalenes. In this work, both the Lewis acid and the nucleophile play significant roles in controlling the reaction pathway. In the presence of AgSbF6, the reaction of 2-(2-cyclopropylethyny arylidene)-1,3-dicarbonyl compounds afforded naphthalen-2(1H)-ones and naphthalenes in up to>20:1 ratio, whereas it afforded naphthalenes and naphthalen-2(1H)-ones in up to>20:1 ratio under the catalysis of In(OTf)3 in the presence of MeOH. Furthermore, the migration ability of substituent of ketone had a significant impact on selectivity.In the end, we have developed an In(OTf)3-catalyzed highly diastereoselective tandem Nazarov cyclization/intramolecular Conia-ene type reaction of the 2-(2-alkynylarylidene)-1,3-dicarbonyl compounds to synthesize fused bicyclic scaffold with a quaternary carbon stereocenter. It should be noted that the double bonds were exo-selectivity and the fused cycles were cis-configuration. Furthermore, a one-pot strategy has also been successfully accomplished, which provides an efficient and rapid access to polycyclic scaffold from readily available starting materials. Piperidinium acetate is a novel tandem catalyst which promotes not only the Knoevenagel condensation but also the following Nazarov cyclization/ intramolecular Conia-ene type reactions.