3-羟基哌啶氮α-碳负离子的形成及α-羟烷化反应

合成了（S）-3-羟基哌啶苯硫醚化合物6作为3-羟基哌啶氮α-碳负离子手性合成子（B）的合成等效体.化合物6经羟基去质子现场保护、萘锂（LN）还原锂化形成手性哌啶醇双负离子中间体B.双负离子B可被质子淬灭得到还原产物2a 而与羰基化合物反应则得到α-羟烷化产物12～17和少量还原产物2a.该反应具有很高的环上2,3-位非对映立体选择性 与非对称的羰基化合物反应产生新手性中心的立体选择性从50：50到77：23.     

铁催化酮羰基的硼化反应合成α-羟基硼酸酯

报道了一种铁催化烷基酮类化合物硼化合成三级α-羟基硼酸酯的反应,使用了可商业购买的FeBr₂作为催化剂,加入醇作为添加剂来加速反应的进行,同时避免副反应的发生.通过该方法合成了一系列三级α-羟基硼酸酯化合物,反应具有很好的底物兼容性以及官能团兼容性.该铁催化剂对于大位阻的酮类化合物的硼化反应,表现出优于铜催化的活性.同时该反应可应用于克级规模的制备,随后通过对三级α-羟基硼酸酯的C-O键进行官能化,将所得的三级α-羟基硼酸酯转化为三级烷基硼酸酯以及偕二硼、偕硅硼类化合物.     

α-羟基取代膦酸酯类化合物的合成研究进展

含磷化合物一直是有机化学研究的热点之一,许多合成药物以及天然产物都含有磷原子。其中,α-羟基取代膦酸酯类化合物是重要的有机合成中间体,其在有机合成中的应用一直受到广泛关注。文章详细综述了α-羟基取代膦酸酯类化合物的合成方法。     

异戊烯金属有机化合物与羰基化合物加成的区域选择性研究进展

异戊烯金属有机化合物与羰基化合物加成反应是合成含α-羟基异戊烯结构单元的天然化合物最简便的方法,但该反应通常生成α-加成和γ-加成两种异构体。不同金属对反应的区域选择性有很大影响。本文综述了异戊烯金属有机化合物与羰基化合物加成反应的区域选择性及其在天然产物合成中的应用。     

铁催化酮羰基的硼化反应合成α-羟基硼酸酯（英文）

报道了一种铁催化烷基酮类化合物硼化合成三级α-羟基硼酸酯的反应,使用了可商业购买的FeBr_2作为催化剂,加入醇作为添加剂来加速反应的进行,同时避免副反应的发生.通过该方法合成了一系列三级α-羟基硼酸酯化合物,反应具有很好的底物兼容性以及官能团兼容性.该铁催化剂对于大位阻的酮类化合物的硼化反应,表现出优于铜催化的活性.同时该反应可应用于克级规模的制备,随后通过对三级α-羟基硼酸酯的C—O键进行官能化,将所得的三级α-羟基硼酸酯转化为三级烷基硼酸酯以及偕二硼、偕硅硼类化合物.     

碱促进下空气氧化合成α-羟基苯乙酰胺

α-羟基酰胺类化合物具有独特的药理和生理活性,引起了有机化学家和药物化学家的广泛关注.目前,这类化合物的合成主要是通过α-羟基苯乙酸的胺基化反应,或者是通过还原α-羰基酰胺类化合物而得到.本工作通过在KOH-DMSO(二甲基亚砜)体系中,利用空气为氧化剂,发展了一种简单高效地制备α-羟基酰胺类化合物的方法.共得到21个α-羟基酰胺产物,并对这些化合物进行了结构表征,其中N-对甲苯基-2-(2-溴苯基)-2-羟基乙酰胺(2a)的结构还通过X射线单晶衍射分析确认.     

α-羟基膦酸酯芳甲酸酯的合成、晶体结构和质谱裂解规律研究

α-羟基膦酸酯与各种取代苯甲酸或吡啶甲酸,通过酰氯或缩合剂的作用,合成了一系列的O,O-二烷基-α-苯基-α-(取代芳基甲酸酯基)-甲基膦酸酯的衍生物.它们的合成收率为61%～84%,这些化合物的结构经过核磁(1HNMR,13CNMR和31PNMR)、红外、质谱、元素分析或高分辨质谱确证,同时化合物C1的结构在晶体结构解析上进一步得到证实.利用多级质谱分析了化合物C2,C5和C8的质谱裂解规律,解释了重排离子的形成机制.     

4-芳亚甲基-2-羟基-3-蒎酮类化合物的合成及其紫外吸收特征研究

以(-)-α-蒎烯为原料合成了系列新型4-芳亚甲基-2-羟基-3-蒎酮类化合物.(-)-α-蒎烯经选择性氧化得到(+)-2-羟基-3-蒎酮;在碱催化作用下,(+)-2-羟基-3-蒎酮与苯甲醛、对甲基苯甲醛、对甲氧基苯甲醛、对羟基苯甲醛、对氯苯甲醛、对硝基苯甲醛和糠醛等芳香醛缩合,得到系列光学活性4-芳亚甲基-2-羟基-3-蒎酮类化合物a～g.采用1H NMR,13C NMR,GC-MS和FT-IR等分析手段对合成所得4-芳亚甲基-2-羟基-3-蒎酮类化合物的结构进行了表征,考察了它们的紫外吸收特性及光稳定性.结果表明,化合物a,b,e对UVB具有良好的吸收性能;而化合物c,d,f,g兼具长波紫外线(UVA)和中波紫外线(UVB)的吸收性能.化合物a～g的光稳定性顺序为d>c>e>f>b>a>g.     

多羟基取代二氢沉香呋喃倍半萜的合成方法

二氢沉香呋喃倍半萜是一类具有杀虫、抑菌等多种活性的天然化合物.由于重要的生物活性和结构的复杂性,从而吸引了有机合成化学家的关注.最近,我们小组从桉烷倍半萜α-(-)-山道年出发,经过NBS促进的四氢呋喃环成环、OsO4双羟基化、环氧化合物的碱重排等一系列官能团转化,合成了七羟基取代的二氢沉香呋喃倍半萜化合物1,进而开拓了一种新颖、简洁的合成多羟基取代二氢沉香呋喃倍半萜的方法,其合成路线如下所示.     

18-甲基腺甾烯酮一类物的酶催化羟化

18-甲基-11α-羟基腺甾-4-烯-3,17-双酮是合成高效口服避孕药的重要中间体。试用黑根霉酶羟化引进11α-羟基于18-甲基-19-失碳雌甾-4-烯-3,17-双酮,得到包括该化合物在内的几种不同位置羟基产物的混合物。改用赭曲霉酶羟化同一底物也得到包括11α-羟基在内的几种不同位置羟基产物的混合物。而用赭曲霉催化羟化18-甲基-17β-羟基腺甾-4-烯-3-酮时,首次得到15α-羟化的主要产物和7β羟化的次要产物。前者可用来合成另一类高效口服避孕药△^15-D-18-甲基炔诺酮。     

DMAP-catalyzed cyanation of aldehydes and ketones with ethyl cyanoformate

The cyanation of carbonyl compounds with ethyl cyanoformate is catalyzed by 4-dimethylaminopyridine (DMAP) to afford the corresponding cyanohydrin carbonates in excellent yields. The system provides a convenient method for cyanation of carbonyl compounds without using metal catalysts or solvents.     

阳极氰化反应的研究进展

本文综述了近30年来阳极氰化反应在有机电合成中的应用,主要回顾了阳极氰化胺、阳极氰化杂环化合物和阳极氰化芳香化合物的研究.此外,还报道了乳化技术在阳极氰化反应中的应用.     

N-heterocyclic carbene catalyzed cyanation reaction of carbonyl compounds with ethyl cyanoformate and acetyl cyanide

N-heterocyclic carbene (NHC) has been employed as an efficient catalyst for cyanation reaction of carbonyl compounds. Under catalysis of 1 mol % NHCs, various aldehydes and 2,2,2-trifluoroacetophenone coupled with ethyl cyanoformate in THF to provide cyanohydrins ethyl carbonates in excellent yields. While in the presence of 10 mol % catalyst, different types of aldehydes and 2,2,2-trifluoroacetophenone reacted with acetyl cyanide in dichloroethane to give acylated cyanohydrins in moderate to high yields.     

One-step remote oxidative cyanation of ketones and aldehydes

Conclusion A one-step general synthesis has been developed for the synthesis of--and -cyano-ketones and cyanoacids, based on the remote oxidative cyanation of carbonyl compounds by the sodium peroxydisulfate-sodium cyanide system.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2725–2734, December, 1986.     

Stereoselective Synthesis of 3,4‐Dihydroxylated Prolines and Prolinols Starting from L‐Tartaric Acid

A straightforward and stereoselective synthesis of 3,4‐dihydroxyprolines and 3,4‐dihydroxyprolinols is described. The key reaction in this synthesis is a protective group‐controlled diastereoselective cyanation of a chiral acyliminium intermediate derived from l ‐tartaric acid. Methanolysis of the obtained cyanolactam gave methyl 3,4‐dihydroxypyroglutamate that was converted to 3,4‐dihydroxyproline and 3,4‐dihydroxyprolinol by reduction of the lactam carbonyl and ester groups in a stepwise manner.     

Cyanide-Free Cyanation of sp2 and sp-Carbon Atoms by an Oxazole-Based Masked CN Source Using Flow Microreactors

This work reports a cyanide-free continuous-flow process for cyanation of sp² and sp carbons to synthesize aryl, vinyl and acetylenic nitriles from (5-methyl-2-phenyloxazol-4-yl) boronic acid [OxBA] reagent as a sole source of carbon-bound masked −CN source. Non-toxic and stable OxBA reagent is generated by lithiation-borylation of bromo-oxazole, and the consecutive Suzuki-Miyaura cross-coupling with aryl, vinyl, or acetylenic halides and demasking [4+2]/retro-[4+2] sequence were successfully accomplished to give the desired cyano compounds with reasonably good yields in a four-step flow manner. A unique feature of this cyanation protocol in flow enables to cyanate a variety of sp² and sp carbons to produce a broad spectrum of aryl acetonitrile. It is envisaged that the OxBA based cyanation would replace existing unstable and toxic approaches as well as non-toxic cyanation using two different sources of “C” and “N” to incorporate the −CN group.     

Direct oxidative cyanation based on the concept of site isolation

On the basis of the concept of site isolation, we have successfully demonstrated direct oxidative cyanation of various organic compounds, which even have higher oxidation potentials compared to that of cyanide, by using a polystyrene-supported quaternary ammonium cyanide.     

Iron(II)‐Catalyzed Direct Cyanation of Arenes with Aryl(cyano)iodonium Triflates

A direct oxidative cyanation of arenes under Fe^II catalysis with 3,5‐di(trifluoromethyl)phenyl(cyano)iodonium triflate (DFCT) as the cyanating agent has been developed. The reaction is applicable to wide range of aromatic substrates, including polycyclic structures and heteroaromatic compounds.     

Dissecting the intimate mechanism of cyanation of {2Fe3S} complexes related to the active site of all-iron hydrogenases by DFT analysis of energetics, transition states, intermediates and products in the carbonyl substitution pathway

A bridging carbonyl intermediate with key structural elements of the diiron sub-site of all-iron hydrogenase has been experimentally observed in the CN/CO substitution pathway of the {2Fe3S} carbonyl precursor, [Fe(2)(CO)(5){MeSCH(2)C(Me)(CH(2)S)(2)}]. Herein we have used density functional theory (DFT) to dissect the overall substitution pathway in terms of the energetics and the structures of transition states, intermediates and products. We show that the formation of bridging CO transitions states is explicitly involved in the intimate mechanism of dicyanation. The enhanced rate of monocyanation of {2Fe3S} over the {2Fe2S} species [Fe(2)(CO)(6){CH(2)(CH(2)S)(2)}] is found to rest with the ability of the thioether ligand to both stabilise a mu-CO transition state and act as a good leaving group. In contrast, the second cyanation step of the {2Fe3S} species is kinetically slower than for the {2Fe2S} monocyanide because the Fe2 atom is deactivated by coordination of the electron-donating thioether group. In addition, hindered rotation and the reaction coordinate of the approaching CN(-) group, are other factors which explain reactivity differences in {2Fe2S} and {2Fe3S} systems. The intermediate species formed in the second cyanation step of {2Fe3S} species is a mu-CO species, confirming the structural assignment made on the basis of FT-IR data (S. J. George, Z. Cui, M. Razavet, C. J. Pickett, Chem. Eur. J. 2002, 8, 4037-4046). In support of this we find that computed and experimental IR frequencies of structurally characterised {2Fe3S} species and those of the bridging carbonyl intermediate are in excellent agreement. In a wider context, the study may provide some insight into the reactivity of dinuclear systems in which neighbouring group on-off coordination plays a role in substitution pathways.     

Aerobic ruthenium-catalyzed oxidative cyanation of tertiary amines with sodium cyanide

RuCl3-catalyzed oxidative cyanation of tertiary amines with sodium cyanide under molecular oxygen (1 atm) at 60 degrees C gives the corresponding alpha-aminonitriles, which are versatile synthetic intermediates of various compounds such as amino acids and unsymmetrical 1,2-diamines, in excellent yields. This reaction is clean and should be an environmentally benign and useful process.