糖苷合成研究(ⅩⅩⅠ)2-N-(β-D-吡喃葡萄糖-1-基)-6-(4-卤代苯基)-3-哒嗪酮的合成

在相转移催化条件下,2,3,4,6-四-O-乙酰基-1-溴-1-脱氧-α-D-吡喃葡萄糖1与6-(4-卤代苯基)-3(2H)-哒嗪酮2反应,合成了4种新的哒嗪酮葡萄糖苷3;然后用干燥的氨气在0～-5 ℃下处理,得相应的2-N-(β-D-吡喃葡萄糖-1-基)-6-(4-卤代苯基)-3-哒嗪酮4. 这些化合物的结构经IR、1H NMR、13C NMR及元素分析所证实.     

4，5-环氧-α-紫罗兰酮的合成研究

研究以H2O2为氧化剂,钨酸钠／磷酸／十六烷基氯化毗啶原位合成的过氧钨配合物催化α-紫罗兰酮合成4,5-环氧-α-紫罗兰酮的反应,考察了催化剂用量、反应温度、反应时间、pH值、溶剂及季铵盐等因素对反应的影响。结果表明,以1,2-二氯乙烷作溶剂,nα-紫罗兰酮：n钨酸钠：n磷酸：n十六烷基氯化吡啶：n过氧化氢=100：0.3：0．1：0．2：120,pH值为4．0,65℃的条件下反应6h,收率可达85％,其结构通过MS、^1H-NMR、IR、EA等检测技术进行表征。     

氮羟基邻苯二甲酰亚胺催化的α-紫罗兰酮的氧化反应

以分子氧（O₂）为氧化剂,在无溶剂条件下,研究了N-羟基邻苯二甲酰亚胺/乙酰丙酮亚钴(Ⅱ)体系对α-紫罗兰酮的催化氧化反应,分析了氧化产物,主要得到α-紫罗兰酮的烯丙位氧化产物5-氧代-α-紫罗兰酮,同时生成少量环氧α-紫罗兰酮及重排产物4-氧代-β-紫罗兰酮和环氧β-紫罗兰酮,提出了可能的反应机理,化合物的结构经IR, ¹H NMR, MS和EA等手段得以表征;为了提高5-氧代-α-紫罗兰酮的选择性和催化氧化反应的转化率,优化了催化氧化反应的工艺条件：当反应温度为70 ℃,氧气压力为1.0 MPa,N-羟基邻苯二甲酰亚胺和乙酰丙酮亚钴(Ⅱ)用量分别为α-紫罗兰酮的25%和1.0%,反应10 h,5-氧代-α-紫罗兰酮的产率达53.4%,反应转化率达95.0%以上,平行实验表明,实验重复性良好。     

过渡金属催化的酮羰基导向C—H键官能化反应进展

近二十年来,过渡金属催化的酮羰基导向C—H键活化已发展成为在酮的非传统反应位点构建碳碳键和碳杂键(杂原子为氮、氟和氧原子等)的强有力而快捷的手段.其中,钌、铑、钯、铱等贵金属催化的酮羰基导向C—H键活化反应得到了广泛研究,而廉价3d金属锰、铁和钴催化的酮羰基导向C—H活化反应逐渐成为当前研究的热点.文中按照过渡金属催化的酮羰基导向C—H键官能化的不同反应类型(烷基化、烯基化、酰胺化、芳基化、环化等)综述了该领域近年来(2014～2021)的研究进展.     

N-羟基邻苯二甲酰亚胺/Co(acac)_2催化的α-紫罗兰酮的氧化反应

以分子氧(O_2)为氧化剂,在无溶剂条件下,研究了N-羟基邻苯二甲酰亚胺/乙酰丙酮亚钴(Ⅱ)体系对α-紫罗兰酮的催化氧化反应,分析了氧化产物,主要得到α-紫罗兰酮的烯丙位氧化产物5-氧代-α-紫罗兰酮,同时生成少量环氧α-紫罗兰酮及重排产物4-氧代-β-紫罗兰酮和环氧β-紫罗兰酮,提出了可能的反应机理,化合物的结构经IR、~1H NMR、MS和EA等测试技术得以表征;为了提高5-氧代-α-紫罗兰酮的选择性和催化氧化反应的转化率,优化了催化氧化反应的工艺条件:当反应温度为70 ℃,氧气压力为1.0 Mpa,N-羟基邻苯二甲酰亚胺和乙酰丙酮亚钴(Ⅱ)用量分别为α-紫罗兰酮的25%和1.0%,反应10 h,5-氧代-α-紫罗兰酮的产率达53.4%,反应转化率达95.0%以上,平行实验表明,实验重复性良好.     

α-卤代酮的脱卤新方法

报道了一种以乙醇为溶剂,在锌粉和甲酸铵催化下的α-卤代酮的脱卤新方法。该体系也适用于α,α-二卤代酮和卤代苄的脱卤反应,产物结构结构经~1H NMR,IR和MS(ESI)确证。     

新型螺环六氢山酮素-氧化吲哚-苯并呋喃酮类拼接物的合成及其抗白血病细胞增殖活性

以色酮-氧化吲哚合成子与3-烯基苯并呋喃酮为原料,在催化剂1,8-二氮杂二环十一碳-7-烯作用下,在二氯甲烷中发生Michael/Michael加成关环反应,合成了6个未见文献报道的螺环六氢山酮素-氧化吲哚-苯并呋喃酮类拼接物(3a^3f),产率75%~87%,dr值3/1~5/1,其结构经1H NMR,13C NMR和HR-MS(ESI-TOF)表征。采用MTT法研究了3a^3f对人白血病细胞(K562)的体外抗增殖活性。结果表明:化合物3c,3e和3f对K562增殖有一定的抑制活性。     

α，β-不饱和酮的绿色环氧化

以过氧化氢为氧源,磷钨杂多酸季铵盐为催化剂,研究了α,β-不饱和酮的环氧化反应,考察了溶剂、温度、催化剂用量、反应时间以及底物浓度等因素对环氧化反应的影响. 结果表明,在适宜反应条件下,过氧化氢/磷钨杂多酸季铵盐催化体系可以催化α,β-不饱和酮环氧化,得到相应的环氧化合物,并能取得较好的结果. 其中, 4-甲基-3-戊烯-2-酮的环氧化合物的产率达到了87%.     

以氨基酸为配体的铑催化剂催化苯乙炔和2,4⁃羟基苯甲醛的氧化偶联反应

以氨基酸和1,5-环辛二烯(cod)为配体的铑催化剂催化苯乙炔和2,4-二羟基苯甲醛的氧化偶联反应,并合成了2-苯基-7-羟基-1H-色酮-4-酮.研究了以不同氨基酸为配体的铑催化剂对相同底物的催化效果,结果发现,在相同反应条件下,Rh(cod)(L-Phe)的催化效果最佳.     

铜催化烯烃氰烷基化成环合成含氰吲哚酮

发展一种简单、高效的铜催化活泼烯烃氰烷基化成环合成吲哚酮的方法。 在CuI/DTBP(叔丁基过氧化物)催化作用下, N-芳基丙烯酰胺类化合物与α-氰基偶氮试剂发生自由基环化反应, 高效地合成了一系列含α-氰基季碳中心的吲哚酮, 并探讨了其反应机理。 该方法底物适用范围较广、反应体系温和, 催化体系廉价。     

Highly enantioselective borohydride reductions of 2-phenacylpyridine catalyzed by optically active β-ketoiminato cobalt(II) complexes

The highly enantioselective reduction of 2-phenacylpyridine catalyzed by optically active β-ketoiminato cobalt(II) complexes with pre-modified sodium borohydride was achieved affording in high enantiomeric excess 1-phenyl-2-(2-pyridyl)ethanol, a precursor of sedamine derivatives. The enantioselective sense in the present reduction is discussed and compared to the asymmetric reduction catalyzed by other complex catalysts.     

Biomimetic reduction of nimesulide with NaBH4 catalyzed by metalloporphyrins

The biomimetic reduction of anti-inflammatory drug, nimesulide (1) with sodium borohydride catalyzed by 5,10,15,20-tetraarylporphyrinatoiron(III) chlorides [TAPFe(III)Cl] has been studied in organic solvents under anaerobic and aerobic conditions.     

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.     

Imino-bridged heterocycles. II. Regiospecific synthesis of the 11H-benzo[5,6]cyclohepta[1,2-c]pyridin-6,11-imine and 5H-benzo[4,5]cyclohepta[1,2-b]pyridin-5,10-imine systems

Regiospecific synthetic pathways for two of the eight isomeric benzocycloheptapyridinimines have been developed based upon intramolecular acid catalyzed additions between an amine function and an internal olefin. The requisite amines were generated from known tricyclic ketones by ketimine formation followed by sodium borohydride reduction.     

Fully Diastereoselective Synthesis of Polysubstituted,Functionalized Piperidines and Decahydroquinolines Based on Multicomponent Reactions Catalyzed by Cerium(IV) Ammonium Nitrate

The cerium(IV) ammonium nitrate (CAN)‐catalyzed, three‐component reaction between primary amines, β‐dicarbonyl compounds, and α,β‐unsaturated aldehydes in ethanol heated to reflux, constitutes a general, one‐pot synthesis of 1,4‐dihydropyridines. Their reduction with sodium triacetoxyborohydride furnished piperidine derivatives bearing up to five substituents with full diastereoselectivity in a hitherto inaccessible stereochemical arrangement. The reaction proceeded with no significant loss of enantiomeric purity under mild reduction conditions that are compatible with several functional groups that are normally sensitive to reduction. Octahydroquinolin‐5‐one derivatives, which were prepared by a modified version of the initial multicomponent reaction, were not suitable substrates for the sodium triacetoxyborohydride mediated reduction, but they were transformed into the corresponding decahydroquinolines, including a precursor of the amphibian alkaloid pumiliotoxin C, by catalytic hydrogenation under a variety of conditions.     

Thiosugars Iii. Stereoselective Approach to β-(1→2)-2,3-Dideoxy-2-C-Acetamidomethyl-2-S-Thiodisaccharides From Levoglucosenone

ABSTRACT

β-(1→2)-2,3-Dideoxy-2-C-acetamidomethyl-2-S-thiodisaccharides were synthesized in four steps by a stereoselective base catalyzed Michael addition reaction of 1-thiosugars to α-nitroalkene 4a, a new chiral synthon from levoglucosenone. It was followed by the reduction of the nitro group with a sodium borohydride/cobalt chloride complex and the hydrolytic opening of the 1,6-anhydro ring.     

Studies towards iodine-catalyzed dehydrative-cycloisomerization of pent-4-yne-1,2-diols to di- and tri-substituted furans

An efficient and single-step iodine catalyzed and metal-free synthesis of di and tri-substituted 2-methylfuran derivatives were achieved from 1-popargyl-1,2-diols. Stereospecific synthesis of starting 1,2-diols was achieved by indium mediated Barbier type propargylation on corresponding keto-alcohols or by sodium borohydride mediated reduction of 2-hydroxy-2-propargyl ketones. The furan synthesis proceeded through iodine mediated 5-exo-trig cyclization, dehydration and reductive deiodination. The method was applied to the synthesis of 2-methylfuran fused to phenanthrene, pyrene and acenaphthylene rings.     

Metal Nanoparticle‐Catalyzed Reduction Using Borohydride in Aqueous Media: A Kinetic Analysis of the Surface Reaction by Microfluidic SERS

Hydrides are widely used in reduction reactions. In protic solvents, their hydrolysis generates molecular hydrogen as a second reducing agent. The competition between these two parallel reduction pathways has been overlooked so far since both typically yield the same product. We investigated the platinum‐catalyzed reduction of 4‐nitrothiophenol to 4‐aminothiophenol in aqueous sodium borohydride solution as a prominent model reaction, by using label‐free SERS monitoring in a microfluidic reactor. Kinetic analysis revealed a strong pH dependence. Surprisingly, only at pH>13 the reduction is driven exclusively by sodium borohydride. This study demonstrates the potential of microfluidics‐based kinetic SERS monitoring of heterogeneous catalysis in colloidal suspension.     

Convenient Method for Reduction of C-N Double Bonds in Oximes,Imines, and Hydrazones Using Sodium Borohydride–Raney Ni System

A practical method has been developed for reduction of C-N double bond in oximes, imines, and hydrazones with sodium borohydride catalyzed by Raney Ni. The reactions were carried out in basic aqueous solution, and the desired products were obtained in moderate yields after a simple procedure. This method can be applied to synthesize simpler aliphatic or aromatic amines and its analogs.     

Decomposition of di-tert-butyl nitroxide in aqueous solutions

Di-tert-butyl nitroxide (DTBN) decomposes in aqueous solutions producing 2-methyl-2-nitroso propane (MNP) and tert-butanol. The process is acid catalyzed, it is of second order in DTBN, and takes place with a rate constant of (1.0 ± 0.1) M^?2 s^?1. The reaction is also catalyzed by the anionic surfactant sodium dodecyl sulfate and by Fe(II) and Fe(III) ions. The catalysis by Fe(III) involves a very fast reduction of Fe(III) ions with concomitant formation of 2-methyl-2-nitroso propane. The reaction catalyzed by Fe(II) also produces 2-methyl-2-nitroso propane with a formation rate given by: d[MNP]/dt = (0.25 ± 0.10) [Fe(II)] [DTBN]. This reaction rate is nearly pH independent.