The Synthesis Of Naphthalene Boronic Acids And Derivatives

Arylboronic acids are important synthetic intermediates in organic chemistry. The palladium-catalyzed cross-coupling reaction between organoboron compounds and organic halides or triflates provides a powerful and general method for the formation of aryl-aryl bond. The coupling of diverse phenols with a variety of aryl boronic acids gives diaryl ethers. The coupling of arylboronic acids and amines is an effective carbon-nitrogen coupling method. The 1,4-conjugate addition of arylboronic acids to enones is widely used for carbon-carbon bond formation givingβ-substituted carbonyl compounds. The cross-coupling reaction shows good substrate generality while using relatively nontoxic, inexpensive reagents under mild conditions and provides products in good yields .Natural products, drugs, dyes and agrochemical specialities are synthesized by the coupling of arylboronic acids. Arylboronic acids and esters have rencently attracted considerable attention due to their advantages as reagents, such as ready availability, stability in the air, insensitivity to moisture, and so on.The first chapter briefly reviews the applications of arylboronic acids in biaryl synthesis, synthesis of diaryl ethers, alkyl aryl sulfides and aromatic amines, and catalytic addition reactions. Naphthalene boronic acids are important intermediates in organic synthesis especially in the synthesis of natural products and compounds with biological activities, so this chapter also introduces the applications of naphthalene boronic acids. At last, the methods for synthesis of arylboronic acids and esters were briefly summarized. The main synthetic methods of arylboronic acids in literatures include"traditional method","a One Pot"synthesis, in-situ quenching, etc; the main synthetic methods of arylboronic esters in literatures include palladium-catalyzed cross-coupling reaction, rhodium-catalyzed cross-coupling reaction,"a One Pot"synthesis and cobalt -catalyzed cross-coupling reaction, etc. These methods have potentially advantages and disadvantages, for example, some substrates may not be compatible to vary functional groups, some substrates are not readily available, some reagents are expensive, etc. Therefore we should choose suitable method in a synthesis according to particular application and specific condition.Naphthalene boronic acids as important organic synthetic intermediates are widely applied in the synthesis of natural products and drug molecules. But there are few reports concerning with the synthesis of naphthalene boronic acids and esters. In the second chapter of this thesis, the target compouds were synthesized via some of classical reactions, for instance, methylation reaction of phenolic hydroxyl, Schiemann reaction, demethylase reaction, the reaction of phenolic hydroxyl with trifluoromethanesulfonic anhydride, iodination of diazonium salt, Palladium-catalyzed cross-coupling reaction of pinacol ester of diborons with aryl triflates or aryl iodides, Curtius rearrangement, and so on.In this thesis, 8-fluoro-2-naphthalene boronic acid, 3-fluoro-2-naphthalene boronic acid and 5-fluoro-2-naphthalene boronic acid were synthesized in six steps, the total yields were 30%, 14% and 22% respectively, 6-fluoro-2-naphthalene boronic acidwas synthesized in ten steps, the total yield was 20%, 7-fluoro-2-naphthalene boronic esterwas synthesized in seven steps, the total yield was 27%, 1-fluoro-2-naphthalene boronic acid was synthesized in three steps, the total yield was 32.9%; 8-methyl-2-naphthalene boronic ester, 3-methyl-2-naphthalene boronic ester, 5-methyl-2-naphthalene boronic ester and 6-methyl-2-naphthalene boronic ester were synthesized in five steps, the total yields were 44%, 45%, 21% and 43% respectively, 7-methyl-2-naphthalene boronic ester was synthesized in four steps, the total yield was 64%, 1-methyl-2- naphthalene boronic ester was synthesized in three steps, the total yield was 54%; 3-methoxyl-2-naphthalene boronic acid, 6-methoxyl-2-naphthalene boronic acid and 7-methoxyl-2-naphthalene boronic acid were synthesized in two steps, the total yields were 23.2%, 51.3% and 70.3% respectively, 5-methoxyl-2-naphthalene boronic ester was synthesized in three steps, the total yield was 40.5%, 8-trifluoromethyl -2-naphthalene boronic acid, 5-trifluoromethyl-2-naphthalene boronic acid and 6-trifluoromethyl-2-naphthalene boronic acid were synthesized in five steps, the total yields were 15.8%, 17.8% and 6.9% respectively,...