A Facile Synthesis of Prumycin

Abstract

Benzyl 2,3-anhydro-4-azido-4-deoxy-α-L-ribopyranoside (7), an intermediate for the synthesis of Prumycin was synthesized in 72% yield in seven steps from D-arabinose. Ammonolysis of 7 followed by N-protection with the benzyloxycarbonyl group gave benzyl 4-azido-2-(benzyloxycarbonyl)amino-2,4-dideoxy-α-L-arabinopyranoside (8), which was easily converted to Prumycin.     

一种新颖而简易的硒催化合成硫代氨基甲酸酯的方法

 在硒催化下,苯胺和硫醇在一氧化碳和氧气作用下发生氧化羰基化反应直接生成相应的硫代氨基甲酸酯,收率从中等到良好. 反应在室温无溶剂条件下进行. 催化剂硒能方便地回收且能循环使用.     

手性芳基膦-噁唑啉的简便合成

膦-噁唑啉化合物作为一类“优势配体”,自发现以来就引起化学家们的广泛关注。 现有合成方法存在路线长、收率低、分离困难等问题。 本研究发展了一种合成手性芳基膦-噁唑啉(PHOX)的简单高效方法。 在1-羟基苯并三唑(HOBt)、1-(3-二甲氨基丙基)-3-乙基碳二亚胺盐酸盐(EDCI)作用下,2-(二苯基膦基)苯甲酸与多种光学纯的氨基醇发生缩合反应,高收率获得酰胺基醇类化合物;之后酰胺基醇经三苯基膦/三乙胺/四氯化碳体系处理完成噁唑啉环的构建,以64%86%的总收率得到膦-噁唑啉化合物。 随后,合成的化合物(S)-t-BuPHOX被应用于钯催化β-酮酯的脱羧Tsuji烯丙基化反应,得到了80%的收率和84%的ee值。 该新方法具有原料易得、条件温和、收率高等优点。     

A Facile Synthesis of Pechmann Dyes

A facile synthesis of Pechmann dyes has been accomplished by the reaction of substituted N‐phenacyl‐4‐dimethylaminopyridinium halides with dimethyl maleate in the presence of DBU. Based on a related 4‐DMAP elimination product and an isolated monolactone intermediate a reaction mechanism has been proposed. The scope of this synthetic method is determined by the availability of α‐haloaroyl or heteroaroyl derivatives. DBU=1,8‐diazabicycloundec‐7‐ene, DMAP=4‐dimethylaminopyridine.     

A Facile Synthesis of Substituted N-Benzoylthiourea

Abstract

One pot reaction of benzoyl isothiocyanate and Tris(hydroxy- methyl)aminomethane (Tris) at room temperature with polyethylene glycol-400 (PEG-400) as solid–liquid phase-transfer catalyst produced substituted N-benzoylthioureas with high yield. A reasonable pathway for their formation has been suggested.     

一个改进的Dallacker双内酯的合成

以5步反应从邻碘苯甲酸乙酯合成了9,10-二氢-9,9,10,10-双(γ-丁内酯)菲,减少了3步反应,总产率提高7%.又由邻碘苯甲酰氯与乙烷-1,1,2-三羧酸三乙酯缩合,继以消除两个乙酯基合成Dallacker双内酯,反应减少一步,产率则增高13%.还研究了联苯-2,2-二甲酰氯分别与乙烷-1,1,2-三羧酸三乙酯和氰基琥珀酸二乙酯的缩合,均能得到良好的产率.     

A Facile Formal Synthesis of Volicitin

A short and concise synthesis of volicitin is presented. The synthesis is based on repeated chemoselective copper salt cross coupling reactions of alkynes and propargylic halides.     

A Facile Synthesis of Various Butenolides

The synthesis of α'-acyloxy-α,β-unsaturated cyclic ketones from the corresponding α,β-unsaturated cyclic ketones by using manganese (III) acetate in combination with 2-chloropropionic acid followed by subsequent Arbuzov and intramolecular Horner-Emmons cyclization reactions provided a convenient synthetic pathway to various butenolides 4a-d.     

A Facile Synthesis of Substituted Phenylglycines

A convenient scaleable process for the preparation of substituted phenylglycines 2 by a modified Strecker reaction is described. Bisulfite-mediated addition of benzylamine and cyanide anion to substituted benzaldehydes 3 gave the aminonitriles 4 which were hydrolysed in two steps to the N-protected amino acid 1. Debenzylation using catalytic transfer hydrogenation gave the title compounds in good yield.     

A Facile Synthesis of 11-Dodecynal

A three-step synthesis of 11-dodecynal is described.     

A Facile One-Pot Synthesis of Vinpocetine

A one-pot synthesis of vinpocetine from vincamine was established. Lewis acids caused transesterification and/or dehydration of vincamine in EtOH. FeCl₃ catalyzed both transesterification and dehydration while Ti(OEt)₄ selectively catalyzed transesterification.     

A Facile Synthesis of 2-Aminonicotinaldehyde

A synthesis of 2-aminonicotinaldehyde (1) which does not require chromatography and is easily scaled up has been developed. Bromination of 2-amino-3-picoline, protected as a phthalimide (4), produced the gem-dibromide (5), which was reacted with Nh₄OH. The imine intermediate (7) was hydrolyzed with acid, producing (1) in a 56% conversion from 4.     

A Facile Synthesis of Benzoxazolyl Cyclopropanes

2′-Benzoxazolyl substituted cyclopropane derivatives were synthesized in the yield of 73-89% from the reaction of telluronium ylides with chalcones.     

A Facile Synthesis of 3,4-Dialkoxythiophenes

Dialkylation of diethyl 3,4-dihydroxythiophenedicarboxylate followed by ester hydrolysis and acid decarboxylation provides a general route to 3,4-dialkoxythiophenes.     

A Facile Synthesis of Pyrrolidine Derivatives

The Amaryllidaceae alkaloids have attracted considerable attention for their interesting biological activities. [1] Many of these tyrosine derived alkaloids[2] incorporate a hexahydroindole moiety in the structural skeletons. New approaches towards the synthesis of hexahydroindole core have been a topical interest for the synthetic community.Herein we report an experimentally very simple method for the synthesis of hexahydroindole by aminocylization. Four kinds of N-substituted have been demonstrate to be effective to this cyclization. The results were summarized in Figure 1.     

A Facile Synthesis of Biscyclopropane Derivatives

Abstract: Bis(dibutyltelluronium)p-xylylene dibromide reacts easily with α,β-unsaturated carbonyl compounds to give biscyclopropane derivatives in high yield.

     

A Facile Synthesis of Squamosamide Cyclic Analogs

A series of novel cyclic derivatives have been synthesized by utilizing a nickel powder mediated radical cyclization as the key step. The structures of the new compounds were confirmed by ^lH-NMR and MS.     

A Facile Synthesis of Indole-based Conjugated Derivatives

A novel synthetic method was developed for the preparation of indole-based conjugated derivatives with satisfied yields. By applying this strategy, a series of new compounds were prepared conveniently. All the obtained new indole derivatives were characterized by spectroscopic analyses, giving satisfactory data corresponding to their expected molecular structures.     

Facile Synthesis of Novel Aminopyrrolobenzimidazole System via Regioselective Amination

A new series of substituted pryrrolobenzimidazoles have been prepared via regioselective displacement of chlorine atom from dichloropyrrolobenzimidazoles with various amine nucleophiles. The dichloro compounds were obtained from the reaction of ortho phenylene diamine compounds with dichloromaleic anhydride.     

A Facile and Efficient Synthesis of Organocyclosiloxanes

A new facile preparative method for the synthesis of organocyclosiloxanes is reported. Ring closure of the dichlorosilanes with NaHCO 3 and pyridine gave mixture of organocyclosiloxanes with cyclotrisiloxane as a main product.