Development of New Organic Reactions by Use of Electron Acceptor Quinones

[2+2]光环加成作用：用乙基乙烯醚照射各种间取代和对取代的同苯醌，使[2+2]光加合物具有区域选择性和内选择性。加合物的反式是由同苯并醌的阻碍较少的一侧加入乙基乙烯醚而形成的。C = C双键上的CH_3、Cl、Br和ch3o取代基主要发生头-头加成反应。在CH_3、Cl和Br的情况下，乙氧基在内位取向，而CH_3O取代基与外位异构体形成1/5的混合物。还发现br取代的[2+2]加合物容易发生骨架重排，被转化为对取代的二氢苯醌衍生物和间取代的二氢邻苯并呋喃衍生物，这可能是在原位生成的HBr的影响下发生的。在碱、碱土金属、高氯酸铵和三氟甲烷磺酸钪的催化下，15-21元醌冠醚1a-c和18元醌冠醚1d与环戊二烯发生了Diels-Alder反应。碱金属离子对每个冠醚具有选择性的速率加速作用，这是由于孔内离子的配合作用。然而，对于二价碱土（Mg^<2+>到Ba^<2+>）和三价Sc^<3+>离子催化的反应，没有观察到这种空穴大小的选择性。包裹络合在速率加速中发挥了重要作用，最小的Mg^<2+>对最灵活的1c产生了160倍的速率增强，而Sc^<3+>对18元喹啉冠1d产生了最大的3700倍的速率增加。与环戊二烯HOMO的轨道相互作用有利于LUMO能量的降低，从而使这些阳离子识别效应合理化。速率增强的幅度是根据阳离子结合亲和力和配位几何构型以及阳离子的价来解释的。少

[2+2] photocycloaddition: Irradiation of various meto- and para-substituted homobenzoquinones with ethyl vinyl ethers gave the [2+2] photoadducts regio- and endo-selectively. The adducts have an antiform built by the addition of ethyl vinyl ethers from the less hindered side of homobenzoquinones. All of the CH_3, Cl, Br, and CH_3O substituents at the reacting C = C double bond afforded head-to-head addition predominantly. In the case of CH_3, Cl, and Br, the ethoxy group was -oriented in the endoposition, while the CH_3O substituent led to a 1/5 mixture with the exo-isomer. It was also found that the Br-substituted [2+2] adducts undergo a facile skeletal rearrangement, being converted into dihydro-obenzoquinone methide for para-substituent and dihydro-o-benzofuran derivatives for meta-substitution, probably under the influence of the in sit generated HBr.Diels-Alder reactions of quinocrown ethers: 15-21-membered auinocrown ethers 1a-c and 18-membered quinobenzocrown ether 1d with cyclo … More pentadiene were catalyzed by the addition of alkali, alkaline earth metal and ammonium perchlorates, and scandium trifluoromethane-sulfonate. The alkali metal ions brought about a fairly selective rate-acceleration for each crown ether due to the size-fitted ion-in-the-hole complexation. However, such a hole-size-selectivity was not observed for the reactions catalyzed by divalent alkalie earth (Mg^<2+> to Ba^<2+>) and trivalent Sc^<3+> ions. The wrapping complexation played a significant role in rate-acceleration in such a way that the smallest Mg^<2+> caused 160 times rate-enhancement for the most flexible 1c and the Sc^<3+> performed maximal 3700 times rate-increment for the 18-membered quinobenzocrown 1d. These effects of cation recognition were rationalized by the reduction of LUMO energy that is favored by the orbital interaction with the HOMO of cyclopentadiene. The magnitude of rate-enhancement was expained in terms of the cation binding affinity and coordination geometry of quinocrown ethers as well as the valence of cations. Less