Ketone-directed Alkylation And Intramolecular Dehydrogenation To Synthesize Isocoumarins

The traditional methods for constructing C-C/C-O bonds have some disadvantages such as many by-products,poor atom economy,environmental pollution,high costs and tedious steps.In contrast,the direct addition of C-H bonds to C=C bonds and intramolecular dehydrogenative coupling reactions provide an efficient and green routes for synthesizing complex organic compouns due to their high atomic utilization and environmental friendliness.Based on direct addition of C-H bonds to C=C bonds and dehydrogenative coupling reactions,the following two works were carried out in this thesis.1.The alkylation reaction of aromatic ketones was realized via direct addition of C-H bonds to C=C bonds directed by carbonyl using aromatic ketones as starting materials.Both enol and ?,?-unsaturated ketone can all be used as alkylation reagent.A series of 2-alkyl substituted aromatic ketones were obtained in good to excellent yields.This method features mild reaction conditions,excellent yields and broad substrate scope.2.Employing 2-(3-oxoalkyl)aromatic acids as starting materials and cheap copper salt as additives,divergent syntheses of isocoumarin and 3,4-dihydroisocoumarin compounds were achieved by Csp3-H bonds and O-H bonds intramolecular dehydrogenative coupling reations to form C-O bonds in air.When using CuCl as additive,the 3,4-dihydroisocoumarins can be obtained in short time(20 min).Replacing CuCl by Cu(OTf)2 and CuCl2·2H2O,the isocoumarins were selectively synthesized.The advantages of this protocol include simple operation,air atmospheres,short reaction time,broad substrate scope,and cheap additives.