Novel Synthetic Method of 2, 6-Naphthalenedicarboxylic Acid

为了开发合成2，6-萘二甲酸1的新路线，对钯催化的环羰化反应进行了广泛的研究。主要研究结果如下：1.2-甲基-3-(对甲苯基)烯丙基乙酸酯在Net_3、Ac_2O和PdCl_2(PPh_3)_2催化下的环羰基化反应，以较高的产率制得1-乙酰氧基-3，7-二甲基萘，并转化为相应的苯磺酸盐。Pd(OAc)_2-dppb催化苯磺酸盐氢解生成2，6-二甲基萘，其氧化制1是众所周知的。因此，这些反应开辟了一条新的合成路线：1.通过环碳酰化反应合成了5-乙酰氧基-1-萘甲酸，并研究了其与4-乙酰氧基苯甲酸共聚物的物理性质。通过3-呋喃、3-噻吩基、3-吡咯基和3-吲哚基烯丙基乙酸酯的环羰化反应，高产率地合成了乙酰氧基苯并呋喃、乙酰氧基苯并噻吩类、乙酰氧基吲哚和乙酰基咔唑。以异硫醇为原料合成了大麻呋喃，证明了该反应的合成价值。3，3-二芳基烯丙基乙酸酯的环羰化反应生成了对芳基取代的稠苯乙酸酯，其中环化反应选择性地发生在更富电子的环上。这一结果表明，该反应涉及钯配位的酰基对芳香环的分子内亲电攻击。2，4-戊二烯基乙酸酯的环羰基化反应以较高的产率得到乙酸苯酯。该反应提供了一条通用的合成取代苯酯的通用路线，包括3，5-或2，3-二取代苯酯，这是传统的苯酚亲电取代反应难以获得的。

With the aim of developing of a novel route to 2, 6-naphthalenedicarboxlic acid 1, the palladium catalyzed cyclocarbonylation was extensively studied. The major results are as follows :1. Cyclocarbonylation of 2-methyl-3-(p-tolyl)allyl acetate in the presence of NEt_3, Ac_2O, and a catalytic amount of PdCl_2(PPh_3)_2 gave 1-acetoxy-3, 7-dimethylnaphthalene in a good yield, which was converted to the corresponding benzenesulfonate. Hydrogenolysis of the benzenesulfonate catalyzed by Pd(OAc)_2-dppb afforded 2,6-dimethylnaphthalene, whose oxidation to 1 is well-known. Therefore these reactions accomplish a novel route to 1. Synthesis of 5-acetoxy-1-naphthoic acid via the cyclocarbonytlation and physical properties of its copolymer with 4-acetoxybenzoic acid were also investigated.2. Acetoxybenzofurans, acetoxybenzothiophenes, acetoxyindoles, and acetoxycarbazoles were obtained in high yields by the cyclocarbonylation of 3-furyl, 3-thienyl, 3-pyrrolyl, and 3-indolylallyl acetates, respectively. The synthetic utility of the reaction was demonstrated by the synthesis of cannabifuran from isothymol.3. Cyclocarbonylation of 3,3-diarylallyl acetates afforded p-aryl-substituted fused phenyl acetates where the cyclization occurred selectively on the more electron rich ring. This result suggests that the reaction involves the intramolecular electrophilic attack of the acyl group coordinated by palladium on the aromatic ring.4. Cyclocarbonylation of 2, 4-pentadienyl acetates was revealed to give phenyl acetates in good yields. This reaction provides a versatile and general synthetic route to substituted phenyl esters including 3, 5- or 2, 3- disubstituted ones, which are hardly obtainable by conventional electrophilic subs titution reactions of phenol.