4,5,6,7-四氢吡唑并[1,5-a]哌嗪-3-甲酸乙酯的合成

以4-氯-3-氧代丁酸乙酯为原料,经与叔丁醇钾醚化、DMF-DMA缩合、水合肼环合、脱叔丁基、羟基氧化、还原氨化、分子内环合以及氢化脱苄等反应合成了标题化合物。并对其中关键的羟基氧化反应和分子内环化反应的工艺条件进行了优化,获得了较优的工艺条件:在羟基氧化反应中以二氧化锰为氧化剂、氯仿为溶剂;在分子内环化反应中以甲基磺酰氧基(OMs)为离去基团。目标化合物的总收率为39.5%,其结构经~1HNMR、~(13)CNMR、MS和元素分析进行了确定。     

分子内还原Heck反应合成7-溴-1-茚满酮

研究了标题化合物的合成新方法,即以邻溴苯甲酸为原料,经取代反应、氧化还原反应、格氏反应以及分子内还原Heck反应合成了目标化合物。探讨了分子内还原Heck反应中反应溶剂、反应温度、反应时间及催化剂种类等条件对产率的影响。最终确定了以四氢呋喃为溶剂、Pd(dppf)Cl_2为催化剂、60℃反应6 h的最佳反应条件,产率可达83%。     

天然棉籽油臭氧化反应机理及过程研究

为了研究天然棉籽油在不同溶剂中的臭氧化反应历程,合成高过氧化值的臭氧化油,以棉籽油为原料,通过臭氧氧化制备了一系列臭氧化油,利用红外光谱(IR)、核磁氢谱(1H-NMR),异核碳氢相关谱(HMQC)和长程异核碳氢相关谱(HMBC)解析了棉籽油中双键臭氧化的反应历程和产物结构,并优化了乙酸乙酯溶剂体系的臭氧化过程的工艺条件。结果表明:乙酸乙酯溶剂中,羰基氧化物与醛反应,主要产物为臭氧化物;而甲醇溶剂中,羰基氧化物易与过量醇发生反应,主要产物为过氧羟基和甲氧基的双官能团产物;在棉籽油的加入量为25 g,进口臭氧浓度80 mg/L,进口流量3 L/min,乙酸乙酯添加量50 g,反应时间2 h下,棉籽油双键转化率可达99%,产物过氧化值为1 990.73 mmol/kg,所获得的臭氧化棉籽油热稳定性好。     

臭氧化反应在香料工业中的应用

臭氧(O_3)常用来氧化不饱和烯烃化合物然后分解生成两个较小的分子——醛、酮或醇。由于臭氧化反应非常迅速,即使在极其温和的条件下,双键也能定量地开裂,所以臭氧化反应有时也被用来确定双键的位置和测定不饱和化合物的结构。进行臭氧化反应时,通常是将臭氧通入烯烃化合物的四氯化碳、石油醚或醋酸溶液中,臭氧加成在双键上,并生成不稳定的臭氧化物;臭氧化物与水作用,即分解成醛或酮:     

3-氰基-4-哌啶酮盐酸盐的合成与表征

以β-丙氨酸甲酯盐酸盐和丙烯腈为原料,经氨基的迈克尔加成、Boc(叔丁氧羰基)保护、分子内环合以及脱保护等4步反应制备了3-氰基-4-哌啶酮盐酸盐,总收率73.7%。对关键的杂原子的迈克尔加成和分子内环合的反应条件进行了优化,得到了迈克尔加成反应较佳的工艺条件:甲醇为溶剂,甲醇钠为碱,丙烯腈∶β-丙氨酸甲酯盐酸盐∶甲醇钠为1.25∶1∶1(物质的量比),反应温度为50℃,反应时间为6h;环合反应较佳的工艺条件:以甲苯为溶剂,氢化钠为碱,反应温度为80℃,反应时间为2h。目标产物的结构经核磁共振氢谱、碳谱和质谱确证。     

一种合成环丁烯酮衍生物的新方法

介绍了一种在碱性条件下以α-丙酰基二硫缩烯酮与胺类化合物为反应原料,DMSO为反应溶剂,发生分子内环化反应合成环丁烯酮衍生物的新方法。其中合成了3个新化合物,产物结构经1H NMR确证。     

5-咪唑甲基-二氢吡咯-3-甲酸甲酯的合成

以组氨酸为原料,经选择性咪唑环氮的保护、氨基迈克尔加成、甲基化、关环、还原和消除等反应合成了标题化合物.对其中关键步骤氨基迈克尔加成反应和分子内关环反应进行了研究,获得了较优的工艺条件:在迈克尔加成反应中以甲醇钠为碱,甲醇为溶剂;在分子内环化反应中选择以叔丁醇钾为碱,四氢呋喃为溶剂.目标产物的总收率为28.3％,结构经1HNMR和MS进行了确证.     

酸处理活性炭催化臭氧氧化肉桂醛为苯甲醛

以经酸处理的活性炭为催化剂,进行多相催化臭氧氧化肉桂醛为苯甲醛。考察了溶剂种类、乙醇用量、活性炭用量、臭氧流量及臭氧化反应温度对反应的影响。结果表明,活性炭能够明显提高臭氧的利用率,臭氧利用率从单独使用臭氧时的53.5%提高到67.4%。最佳反应条件为:无水乙醇为溶剂,m(无水乙醇)/m(肉桂醛)=3,氧气流量为800 mL/min(臭氧流量为0.71 g/h),m(活性炭)/m(肉桂醛)=0.01,在0℃下臭氧化反应2 h,然后进行还原反应,苯甲醛收率为44.0%。     

新型四唑并[1,5-a]哌嗪类螺环化合物的合成研究

以取代苄胺、1-叔丁氧羰基-4-哌啶酮、叠氮基三甲基硅烷(TMSN3)和异腈化合物为原料,经4组分“一锅煮”反应,得到新型四唑并[1,5-a]哌嗪类螺环化合物.研究了温度和溶剂对反应的影响,得到最佳反应条件:以甲醇为溶剂,65℃回流条件下反应48 h.所有产物结构经1HNMR和MS进行表征.     

环己烯臭氧化合成1,6-己二醛

以环己烯为原料,采用Zn-CH_3COOH为还原剂,经臭氧氧化和还原分解得到1,6-己二醛。讨论溶剂种类、溶剂用量、反应温度、氧气流量、氧化反应时间、还原剂种类、还原分解时间、还原剂用量对环己烯臭氧化合成1,6-己二醛反应的影响。得到较佳反应条件(以0.05 mol环己烯计)为:采用冰乙酸和1,2-二氯乙烷混合溶剂,冰乙酸6 g,1,2-二氯乙烷30 mL,臭氧化温度(0～5)℃,O_2流量(100～200) mL·min^(-1),臭氧化反应时间180 min,活化锌粉为还原剂,n(锌粉)∶n(环己烯)=1∶1,还原分解时间60 min。在该反应条件下,重复实验三次,1,6-己二醛平均收率可达61.6%。     

Electrolytical reduction of maleinamide and fumaramide of 2-nitrobiphenyl-2′-amine at mercury electrodes

The role played by geometric isomerism in the intramolecular cyclization reaction initiated by the electrode reduction of maleinamide and fumaramide of 2-nitrobiphenyl-2′-amine was studied at mercury electrodes. The cyclization reaction leading to the formation of benzo(c)cinnoline occurs with the former substance whereas only a reduction of the nitro group and of the CC double bond could be observed with the latter.     

Polymer nanoparticles via intramolecular crosslinking of sulfonyl azide functionalized polymers

A new approach to prepare polymeric nanoparticles via intramolecular collapse of single chain of sulfonyl azide functionalized polymers is proposed. Upon heating, the sulfonyl azide functionalized linear copolymers lose nitrogen and form nitrene. This nitrene reacts with CH bond of the backbone in dilute solution and leads to the efficient intramolecular crosslinking and formation of nanoparticles where the diameter of nanoparticles can be controlled by both the molecular weight and the content of sulfonyl azide groups. A significant reduction in the hydrodynamic volume is observed on going from the starting random coil of linear chains to the corresponding nanoparticles. The morphology and the dimension of nanoparticles are characterized by using transmission electron microscope (TEM), atomic force microscopy (AFM), as well as dynamic laser scattering (DLS).     

1-溴-5-苯基-四氮唑的合成

以苯甲腈、叠氮钠、溴等为原料,经偶合,溴化合成了1-溴-5-苯基四氮唑。研究了反应时间、反应温度、溶剂与反应物配比对产品收率的影响。实验表明:在n(苯甲腈)∶n(叠氮钠)=1∶1.1,1 mol NH4Cl催化,120℃下反应20 h可得到收率90%的5-苯基四氮唑。在n(5-苯基四氮唑)∶n(溴)∶n(氢氧化钠)=1∶0.97∶0.96,反应4 h,水作溶剂的条件下,可得到56.4%的1-溴-5-苯基四氮唑,两步反应后的总收率为49.1%。     

6-2-氨丙基-2,3-二氢苯并呋喃的合成

以3-甲氧基苯甲醛为原料,经亨利反应、还原硝基和双键、氨基保护、傅-克酰基化、脱甲基、环合、羰基还原等反应,合成目的产物6-2-氨丙基-2,3-二氢苯并呋喃。并对硝基和双键的还原反应、傅-克酰基化和脱甲基反应的工艺条件进行了优化,得出较佳工艺条件:(1)化合物Ⅱ的还原反应:反应温度40℃,氢气压力4.0 MPa,Raney-Ni用量为化合物Ⅱ质量的8%,产物收率为78.6%;(2)合成化合物Ⅵ的反应:反应温度45℃,n(氯乙酰氯)/n(化合物Ⅳ)=1.4,反应时间6 h,产物收率为68.8%。     

On the specificity of allene oxide cyclase

Jasmonic acid is a carbocyclic fatty acid that is biosynthesized from α-linolenic acid in several steps. The formation of the ring structure of jasmonic acid is catalyzed by the enzyme allene oxide cyclase (EC 5.3.99.6) and involves the cyclization of an unstable allene oxide into the cyclopentenone 12-oxo-10,15(Z)-phytodienoic acid. In this study, a number of allene oxides were generated, and their enzymatic and nonenzymatic cyclization into cyclopentenones was investigated. Nonenzymatic cyclization was observed with allene oxides having one pair of conjugated double bonds and an additional isolated double bond in the β,γ position relative to the epoxide group, i.e., the partial structure 4,5-epoxy-1,3,7-octatriene. Enzymatic cyclization took place provided that this structural element was inserted in the fatty acid chain with its epoxide group in the n−6,7 position and the isolated double bond in the n−3 position. A number of oxygenated fatty acids having structural features in common with the natural allene oxides were tested as inhibitors of allene oxide cyclase. Fatty acids having an allene oxide structure in the n−6,7 position but lacking the double bond in the n−3 position, as well as fatty acids having a saturated epoxide group in the n−6,7 position, served as competitive inhibitors of the enzyme. Data on the substrate specificity of allene oxide synthase (EC 4.2.1.92) from corn seeds indicated that fatty acid hydroperoxides with a double bond at n−3 and with the hydroperoxide function at n−6 exhibit the highest affinity but the slowest reaction velocity.     

Synthetic and mechanistic studies of the cycloisomerization and cyclization/hydrosilylation of functionalized dienes catalyzed by cationic palladium(II) complexes

This Account describes the development and mechanistic study of the cycloisomerization and cyclization/hydrosilylation of functionalized dienes catalyzed by cationic palladium(II) complexes. These transformations are characterized by good functional group compatibility, high regio- and stereoselectivity, and low air- and moisture-sensitivity. Mechanistic studies of palladium phenanthroline-catalyzed diene cycloisomerization and cyclization/hydrosilylation established mechanisms involving C-C bond formation via intramolecular carbometalation of an alkyl olefin chelate complex, which was directly observed in the context of cyclization/hydrosilylation.     

肾上腺素的电化学氧化聚合研究

采用电化学石英晶振阻抗分析法,研究了金电极上肾上腺素(EP)循环伏安电氧化形成聚合膜的过程,并考察了溶液pH对聚合过程的影响。结果表明溶液pH在3.31和7.04间,肾上腺素的氧化产物发生环化反应后,进一步氧化在金电极表面沉积形成聚合膜,并提出了可能的聚合机理,且该聚合膜具有优良的阳离子选择渗透性。     

A mild route to α-alkoxyacetylenes mediated by lewis acids and synthetic routes to 10-, 11-, and 12-membered ring enediyne carbocycles

The condensation of silyl substituted acetylenes with dimethoxy acetals via a modified “Mukaiyama-type reaction” to afford α-alkoxyacetylenes is described. These propargylic ethers 17–21 were synthesized from the reaction of aluminum or zinc acetylides with acetals mediated by Lewis acids. In appropriate cases, when a second acetal was present in the initial acyclic product ( 24 ), a subsequent intramolecular acetal-ene (Prins) cyclization ensued to afford the silylalkylidenealkoxycyclopentane ( 25 ). Enediyne species were unreactive under these conditions, even in an intramolecular case. Routes to 11- and 12-membered carbocyclic enediyne compounds ( 43, 44 ) were developed via an intramolecular pinacol coupling of the dialdehydes 39 with sammarium diodide/HMPA. The requisite double bond was introduced using the thiocarbonate expulsion method with trimethyl phosphite. A route to the highly substituted 10-membered ring enediyne 50 is also described based on the use of an isopropylidene acetal tether control group to facilitate an intramolecular chromium (II)/nickel (II)-mediated coupling of the iodoacetylene aldehyde 49 .     

Studies on the Oxidation of cis- and trans-Pinane with molecular oxygen

The pinanes are preferably attacked at the tertiary C-H bond in 2-position, but products of the oxidative attack at the secondary C-H bonds in 3- and 4-position are also found. At 100°C cis-pinane is attacked more easily than trans-pinane (k_cis : k_trans = 6.4), the relative rates of attack at the secondary C-H bonds in positions 3 and 4 with respect to the tertiary C-H bond in 2-position were also determined (in cis-pinane k_sec: k_tert = 0.027; in trans-pinane k_sec : k_tert = 0.20). After the attack at the 2-C-H bond the radical formed can either react with oxygen to form the corresponding cis- and trans-peroxy radicals and further to give cis- and trans-2-hydroperoxy pinane or fragmentate to the monocyclic radical derived from α-terpinene, giving as final products α-terpinene hydroperoxide and the bicyclic 8-hydroperoxy 4,4,8-trimethyl 2,3-dioxabicyclo[3.3.1]nonane. The corresponding alcohols were found after reduction with sodium sulphite. The oxidation at position 2 of the pinanes delivers not only the cis- and trans-hydroperoxide but also, as shortlived intermediates, the corresponding 2-pinanyloxy radicals. These radicals fragmentate forming a carbon radical with cyclobutane structure whose oxidation products were identified. Besides fragmentation of the 2-pinanyloxy radical also an intramolecular H-transfer from the methyl group in 9-position to the oxygen of the trans-2-pinanyloxy radical takes place leading to 9-hydroperoxy trans-pinane-2-ol.