选择脱卤还原反应的研究

Ramasamy、Osuka等用NaHTe/EtOH研究了二卤代物的脱邻二溴、偕二溴反应和α-溴代羰基化合物的脱卤还原反应,我们选择结构不同的卤代物以NaHTe还原,发现在水介质和催化量碲代替计算量碲时也能顺利地进行这类反应,其反应条件温和,产率高,是有机官能团转化的好方法。     

烯胺化学

烯胺(enamines)是指具有结构的一类化合物的总称,但是习惯上所谓烯胺往往是指α,β-不饱和三级胺。烯胺这类化合物虽然早被知道,然而,被化学工作者所重视还只是近十年来的事。在1954年Stork利用烯胺作为中间体提出了一类羰基化合物的烷基化和酰基化的新合成方法。这类合成方法不需要碱性催化剂,可以免除碱催化的烷基化和酰基化反应中由于碱的存在而引起的许多困难,如自缩合反应、Michael反应、再烷基化等副反应。近年来利用这一反应合成了许多难以制得的化合物,提供了     

铜催化胺与1,3-二羰基化合物的缩合反应合成烯胺酮化合物

报道了铜催化胺与1,3-二羰基化合物的缩合反应.在CuCl催化剂的存在下,胺与1,3-二羰基化合物的缩合反应,可在四氢呋喃溶剂中、室温条件下顺利进行,生成烯胺酮化合物,收率为75%～98%.合成了16种烯胺酮化合物3a～3p,其中,3p为未知化合物.     

FeCl3催化羰基化合物与芳烃的还原Friedel-Crafts烷基化反应

在二甲基氯硅烷作用下, FeCl3能催化羰基化合物(醛、酮)与芳烃及噻酚的还原Friedel-Crafts烷基化反应, 在温和的条件下一步实现羰基化合物的还原和C—C键的构造.     

FeCl3催化羰基化合物与芳烃的还原Friedel-′Crafts烷基化反应

在二甲基氯硅烷作用下,FeCl3能催化羰基化合物（醛、酮）与芳烃及噻酚的还原Friedel—Crafts烷基化反应,在温和的条件下一步实现羰基化合物的还原和C—C键的构造．     

不对称三烯胺催化的发展

手性胺可以与多不饱和羰基化合物原位生成三烯胺中间体,其给电子效应根据插烯规则可通过共轭不饱和体系传递,进而提高三烯胺体系的HOMO能量,并能够在远端β,ε-或δ,ε-位与多种缺电子烯烃发生Diels-Alder环加成反应。采用这种合成策略,可以制备许多结构多样和复杂的环状手性化合物。这种策略除了能够高效地在羰基化合物远端直接实现官能团化,更重要的是ε-反应位点即使距离催化剂手性中心达七个键之远,仍能获得优秀的立体选择性控制,这在不对称合成中具有重要的研究价值。本文将总结近年来不对称三烯胺催化机制的发现及发展,重点介绍2,4-二烯醛、多种二烯酮、含羰基芳香化合物经由三烯胺、交叉共轭三烯胺或形式三烯胺进行的不对称反应,并对手性胺催化的进一步应用进行展望。     

手性质子酸催化酮的不对称直接α-烷基化反应研究

在有机合成中,羰基化合物的α-烷基化反应是一种重要的碳碳键形成策略.羰基化合物的不对称α-烷基化反应已经有较多的研究报道,但是,在已有的报道中多是使用脂肪醛作为烷基化反应的给体和手性胺作为催化剂.手性胺催化脂肪酮的不对称α-烷基化反应其立体选择性不是十分理想.西南大学化学化工     

过渡金属催化1,3-二羰基化合物不对称烯丙基烷基化反应的研究进展

1,3-二羰基化合物的不对称烯丙基烷基化反应是构筑手性中心的重要方法.综述了过渡金属催化1,3-二羰基化合物不对称烯丙基烷基化反应的进展.按照烯丙基化试剂的不同,主要讨论了以烯丙基酯类、烯丙醇、烯丙基卤化物、烯烃、联烯作为烯丙基化试剂或其他烯丙基化方法合成手性α-烯丙基取代的1,3-二羰基化合物.     

碲氢化钠与胺烷基化苯并三氮唑的反应

碲氢化钠是一个用途广泛的磁试剂,自作为有用的去溴试剂以来,日益受到化学工作者的关注,不断有文献报道它的合成及应用.例如能有效地还原卤代烃、硝基化合物、叠氮化合物和亚胺等.近年来,Katritzky报道了胺烷基化苯并三氮唑衍生物的合成及应用,此衍生物中的苯并三氮唑基是很好的离去基团,易被各种亲核试剂所取代.我们在前文中对硒氢化钠与胺烷基化苯并三氮唑反应生成二苄基二硒醚的合成进行了报道.本文用碲氢化钠与胺烷基化苯并三氮唑反应,结果生成还原产物N-取代胺.     

含烯烃配体的过渡金属配合物的研究 Ⅳ.钼和铬的环庚三烯二羰基[乙氧基(芳基)卡宾]配合物的合成和晶体结构

不久前,我们报道了丁二烯三羰基铁和异戊二烯三羰基铁与亲核试剂芳基锂在低温下反应,再用Et_3OBF_4烷基化,可分别获得一族新奇的异构化的丁二烯-和异戊二烯二羰基[乙氧基(芳基)卡宾]铁配合物。我们又发现环辛四烯三羰基铁与芳基锂进行类似的反应,也不生成正常的环辛四烯配位的卡宾配合物,而是得到一系列具有新奇结构的环辛四烯二羰基[乙氧基(芳基)卡宾]铁的异构化产物和(或)环辛三烯三羰基芳基铁配合物。这些产物的结构显示了烯烃在金属化合物中的键合方式是复杂多样的,十分令人感兴趣。因此,我们选择了含奇数碳的环状共轭三烯配体的环庚三烯三羰基钼和铬,在类似的条件下与芳基锂进行反应,以研究不同种类的烯烃配体和不同中心金属对反应产物的影响。     

Further studies on vinamidinium salt amine exchange reactions, borohydride reductions and subsequent transformations

Studies directed at the amine exchange reaction of vinamidinium salts followed by sodium borohydride reduction to secondary and tertiary allylic amines are described. The tertiary allylic amines were alkylated and subjected to base mediated rearrangement to yield a variety of highly functionalized tertiary homoallylic amines.     

Novel Synthesis of Optically Active 2‐Ethylhexanoic Acid, 2‐Ethylhexanol,and 2‐Ethylhexylamine via the Asymmetric Favorskii Rearrangement

The asymmetric Favorskii rearrangement of optically active α‐haloketones, which are easily prepared from chiral menthyl‐4‐toluenesulfoxide in several steps using primary or secondary amines, yields their corresponding secondary or tertiary chiral amides. The secondary chiral amides were converted to acids or amines using acylation followed by hydrolysis or reduction. In addition, the tertiary amides were directly reduced to alcohol with Super‐Hydride^®.     

Selective Analysis of Secondary Amines Using Liquid Chromatography with Electrochemical Detection (LC‐EC)

In a mixture of primary and secondary aliphatic amines, the primary amines were derivatized (masked) with o‐phthalaldehyde (OPA) followed by derivatization of the remaining secondary amines with ferrocenecarboxylic acid chloride (FAC). The “tagged” amines were analyzed by LC‐EC (liquid chromatography with electrochemical detection) using in‐series dual electrode detection. Chemically‐reversible oxidation of the FAC tagged secondary amines and their subsequent complementary oxidation and reduction signals coupled with chemically‐irreversible oxidation of OPA tagged primary amines provided the selectivity for quantitative secondary amine analysis. The procedure was also applied for the selective identification of fragment 4–11 (N‐terminus‐proline) of Substance P in the presence of other Substance P fragments with primary amino acids as their N‐termini.     

Amberlite IRA-400 Cl resin catalyzed synthesis of secondary amines and transformation into N-((1H-indol-3-yl) (heteroaryl) methyl)-N-heteroaryl benzenamines and bis-indoles via multicomponent reaction

A one-pot Amberlite IRA-400 Cl resin catalyzed the in-situ generation of imines from various aldehydes and primary amines followed by reduction with sodium borohydride affording corresponding secondary amines. The secondary amines thus obtained were utilized for the IRA-400 Cl resin catalyzed multicomponent synthesis of 3-aminoalkylated indoles using a number of aldehydes and indole. Mild condition, easy work-up, and environmentally benign nature of the synthetic strategy make it both practical and attractive.     

Reductive hydroxyalkylation/alkylation of amines with lactones/esters

We have developed a one-pot method for the direct intermolecular reductive hydroxyalkylation or alkylation of amines using lactones or esters as the hydroxyalkylating/alkylating reagents. The method is based on the in situ amidation of lactones/esters with DIBAL-H-amine complex (for primary amines) or DIBAL-H-amine hydrochloride salt complex (for secondary amines), followed by reduction of the amides with an excess of DIBAL-H. Different from the reduction of Weinreb amides with DIBAL-H where aldehydes are formed, the reduction of the in situ formed Weinreb amides yielded amines. Moreover, this method is not limited to Weinreb amides, instead, it also works for other amides in general. A plausible mechanism is suggested to account for the outcome of the reactions.     

Effect of the Temperature on the Stoichiometry of Borane Dimethyl Sulfide Reduction of Secondary and Tertiary Amides

A simple procedure has been described for the reduction of secondary and tertiary amides to amines using borane-dimethyl sulfide in theoretical amounts.     

Synthesis and some transformations of 2-[2-isopropyl-4-(3-methylbutyl)tetrahydropyran-4-yl]-ethylamine

The condensation of 2-[2-isopropyl-4-(3-methylbutyl)tetrahydropyran-4-yl]ethylamine with aromatic aldehydes followed by reduction gave rise to secondary amines of tetrahydropyrane series. Reactions of the obtained amines with acetyl chloride, succinic and phthalic anhydrides resulted in the corresponding acetamides, succinimide, and phthalimide.     

Solid-phase synthesis of trisubsituted guanidines

The solid-phase library synthesis of trisubstituted guanidines was accomplished. Amines were loaded onto the 4-formyl-3,5-dimethoxyphenoxymethyl linker via reductive amination. Subsequent acylation with Fmoc-4-aminomethylbenzoic acid followed by Fmoc deprotection gave solid-supported primary amines. Alternatively, sulfonylation of resin-bound secondary amines with 4-cyanobenzenesulfonyl chloride followed by borane reduction also gave solid-supported primary amines. Both resins were acylated with isocyanates to furnish solid-supported ureas. Dehydration of ureas with p-toluenesulfonyl chloride in pyridine gave solid-supported carbodiimides. Nucleophilic addition of amines to the carbodiimide bond followed by cleavage off the solid support gave trisubstituted guanidines.     

Preparation of functionalized primary chiral amines and amides via an enantioselective three-component synthesis of propargylamines

A general preparation of functionalized primary chiral amines and amides from propargylamines has been developed. The chirality is established by an enantioselective three-component reaction of an aldehyde, a terminal alkyne and a secondary amine in the presence of copper(I) bromide/Quinap as the catalytic system leading to chiral propargylamines in high yields and enantioselectivities. Functionalization and reduction leads to various primary amines and amides.     

Cu-catalyzed reduction of azaarenes and nitroaromatics with diboronic acid as reductant

A ligand-free copper-catalyzed reduction of azaarenes with diboronic acid as reductant in an aprotic solvent under mild conditions has been developed. Most interestingly, the nitroazaarenes could be reduced exclusively to give the corresponding amines without touching the azaarene moieties. Furthermore, the reductive amination of aromatic nitro compounds and aromatic aldehydes has also been realized. A series of hydrogenated azaarenes and secondary amines were obtained with good functional group tolerance.