7,8-二氢-6,6-二甲基-7,8-环氧-6氢-吡喃[2,3-f]苯并-2,1,3-噁二唑的合成

本文给出了一条较好的制备7,8-二氢-6,6-二甲基-7,8环氧-6氢-吡喃[2,3-f]苯并-2,1,3-噁二唑的合成路线,即由对乙酰氨基苯酚经酯化、Fries重排、环合、还原、脱水、硝化、脱酰基、氧化、脱氧和催化环氧化等反应制得标题化合物,其结构经元素分析和光谱数据确证。     

维生素丁的研究Ⅰ.——7,8-双羟-7,8-双氢维生素丁二

用高锰酸钾在温和条件下氧化维生素丁二,得到一种新的双羟双氢维生素丁二。根据其紫外吸收光谱及四乙酸铅或高碘酸的氧化结果,证明其结构是7.8-双羟-7,8-双氢维生素丁二。制备5,6-和7,8-双羟双氢维生素丁二的二乙酸酯衍生物,分别应是5,6-双羟-5,6-双氢维生素丁二的3,6-双乙酸酯和7,8-双羟-7,8-双氢维生素丁二的3,7-双乙酸酯。本文并讨论维生素丁二因氧化剂与条件不同所经历不同的反应历程。     

1-(2-炔丙基)-7,8-二氢喹啉-2,5(1H,6H)-二酮的合成

以1,3-环己二酮为原料,依次经亚胺化反应、Michael加成-环化反应、烷基化反应合成了含有端基炔的喹啉酮衍生物——1-(2-炔丙基)-7,8-二氢喹啉-2,5(1H,6H)-二酮,其结构经1H NMR,HR-MS和2D NMR确证。     

7,8-亚甲二氧基-4-氧代-3,4-二氢嘧啶并[4,5-b]喹啉衍生物的合成

为了寻找具有药理活性的喹啉衍生物, 我们合成了五个新的喹啉衍生物和十一个7,8--亚甲二氧基-4-氧代-3,4-二氢嘧啶并[4,5-b]喹啉衍生物. 这些化合物的结构均经核磁共振光谱, 红外光谱和元素分析予以证实 .     

7,8-二氢-8-氧鸟嘌呤碱基对的量子化学研究

遗传信息的完整性不断受氧化基因的威胁,7,8-二氢-8-氧鸟嘌呤（8-oxo-G）是氧化DNA损伤最常见的产物. 氧化碱基会引起基因突变、癌变及衰老等. 应用量子化学方法分析得出：鸟嘌呤（G）被氧化为8-oxo-G后,其电荷分布、氢键的供体和受体位点的数目和位置随之改变,N7和O6原子所带的电荷变得更负,使得它们作为氢键供体的能力增强. 从而G被误认为其他碱基,与正常碱基形成多种氢键复合物. 可将8-oxo-G划分为3个作用位点与正常碱基相互作用. 与正常的单体相比,碱基对中形成氢键的受体原子上所带电荷平均变负0.05e,占原电荷的8%; 供体H原子所带电荷平均变正0.02e,占原电荷的4%. 1位点与正常碱基作用形成的氢键复合物更稳定,2位点和3位点性质相似,水溶剂使碱基对的结合能力减弱,其中与C作用形成氢键复合物的结合能减弱程度最大,且使碱基对结合能力的次序改变. 在8-oxo-G导致的GC→TA突变中,亲核反应位点从G所在链转到A（C）所在链,影响酶对碱基的识别,从而产生基因突变.     

1,3-二(2,6-二甲基苯基)-2-四氢咪唑基-苯亚甲基-二吡啶基-二氯合钌化合物的合成

设计了由1,3-二(2,6-二甲基苯基)-2-四氢咪唑基-苯亚甲基-三苯基膦-二氯合钌(7)和吡啶反应生成无膦型金属钌卡宾化合物1,3-二(2,6-二甲苯基)-2-四氢咪唑基-苯亚甲基-2-吡啶基-二氯合钌(8),8作为高效催化剂用于丙烯腈和烯丙基苯的交叉交互置换反应.新化合物7,8经核磁共振氢谱、碳谱和高分辨率质谱予以证实.     

无溶剂一锅法合成新型8-芳基-7,8-二氢-[1,3]二氧戊环并[4,5-g]喹啉-6(5H)-酮类化合物

采用微波辅助,经三组分(3,4-亚甲二氧基苯胺,2,2-二甲基-1,3-二氧六环-4,6-二酮和取代芳醛)无溶剂一锅法合成了10个新型的8-芳基-7,8-二氢-[1,3]二氧戊环并[4,5-g]喹啉-6(5H)-酮类化合物,产率75.7%~83.5%,其结构经1H NMR,FT-IR,ESI-MS和元素分析表征。     

硅胶键合N-丙基氨基磺酸催化合成8-芳基-7,8-二氢-[1,3]二氧杂环戊烯并[4,5-g]苯并吡喃-6-酮类化合物

120℃、无溶剂条件下,硅胶键合N-丙基氨基磺酸可有效催化芝麻酚、芳香醛和米氏酸三组分一锅法合成8-芳基-7,8-二氢-[1,3]二氧杂环戊烯并[4,5-g]苯并吡喃-6-酮类化合物.考察了温度及催化剂用量对产率的影响.产物的结构经1H NMR,13C NMR,质谱和元素分析进行了表征.     

法可林中间体——7,8-二氨基吩嗪-2-磺酸的合成

研究了3条合成法可林中间体［7,8-二氨基吩嗪-2-磺酸(1)］的工艺路线(路线A~C)。结果表明：路线C为最优反应条件,即以邻苯二胺为起始原料,先用浓硫酸磺化,再经保护-氧化反应,最后脱除保护基合成了1,总收率62.01%,其结构经¹H NMR, ¹³C NMR和ESI-MS确证。     

10,10-二吡啶甲基-9,10-二氢蒽的合成研究

蒽酮1和氯甲基吡啶盐酸盐2在甲苯中回流反应生成10,10-二吡啶甲基-9(10H)蒽酮(3),收率63％～68％;3用硼氢化钠还原生成10,10-二吡啶甲基-9,l0-二氢蒽-9-醇(4),收率87％～90％;蒽醇4在酸催化下发生歧化反应,得到还原产物10,10-二吡啶甲基-9,10-二氢蒽(5)和氧化产物蒽酮3.该歧化反应受催化剂、溶剂和反应温度等影响.当蒽醇4用三氟化硼为催化剂、甲苯为溶剂、回流反应,5的收率达到74％.所合成的新化合物都经1H NMR,13C NMR,MS和元素分析表征确认.     

New ways to derivatize at position 6 of 7,7-dimethyl-7,8-dihydropterin

Reported are the synthesis of two intermediates for derivatization at position 6 of 7,7-dimethyl-7,8-dihydropterin: 6-carboxylic acid ethyl ester-7,7-dimethyl-7,8-dihydropterin, which is a novel compound, and 6-aldehyde-7,7-dimethyl-7,8-dihydropterin, which is synthesized by a new method with a yield of 90%.     

Some stable derivatives of 7,8-dihydropurines

The synthesis of a number of 7,8-dihydropurines is described. The unusual stability of these molecules is due to the presence of an electron withdrawing substituent in the 6-position.     

Use of allylic strain to enforce stereochemistry. Direct syntheses of 7,8-dihydroxycalamenene and mansonone C

[Structure: see text] Direct syntheses of 7,8-dihydroxycalamenene and mansonone C were achieved. The cis-stereochemistry required for the synthesis of 7,8-dihydroxycalamenene was introduced by an intramolecular cyclization directed by allylic strain.     

A novel and facile synthesis of 7,8-diacylcoumarins

Oxidation of N-carbonylhydrazones of 7-hydroxy-8-acetylcoumarin with lead tetraacetate results in the synthesis of 7,8-diacylcoumarins in good yields. The reaction proceeds via the transformation of a hydroxy into an acyl group reported for the first time in heterocyclic chemistry.     

Structure of 6,11-dichloro-9-dimethylthio-7,8-dicarba-nido-undecaborane [6,11-Cl2-9-SMe2-7,8-C2B9H9]

A technique is proposed for directed synthesis of 6,11-dichloro-9-dimethylthio-7,8-dicarba-nido-undecaborane [6,11-Cl₂-9-SMe₂-7,8-C₂B₉H₉]. Single-crystal X-ray diffraction is used to identify the molecular and crystal structure of the compound.     

Convenient Synthesis of 7,8‐Dimethoxytetralin‐2‐one

7,8‐Dimethoxytetralin‐2‐one (1), an important intermediate for the synthesis of compounds possessing biological activity, was synthesized by simple reaction steps from commercially available starting materials.     

7,8-Dioxochlorpromazine,synthesis and properties

7,8-Dihydroxychlorpromazine and 2-chloro-7,8-dihydroxyphenothiazine were converted to the corresponding 7,8-dioxo compounds by oxidation with tetrachloro-o-quinone. Spectral properties indicate that the 7,8-dioxo compounds exist in zwitterionic forms reminiscent of aminochromes. The 7,8-dioxochlorpromazine is proposed as a possible metabolite of chlorpromazine.     

A stereoselective total synthesis of 7,8-O-isopropylidene iriomoteolide-3a

A stereoselective total synthesis of 7,8-O-isopropylidene iriomoteolide-3a has been achieved by using Yamaguchi esterification, Julia-Kocienski olefination, organocatalytic α-oxidation, and ring-closing metathesis reaction as key bond-forming steps.     

A Convenient Synthesis 7,8-Dihydroisoquinolin-5(6H)-One

A new high-yield two step synthesis of 7,8-dihydroisoquinolin-5(6H)-one (3) from 5,6,7,8-tetrahydroisoquinoline (1) is described.