A Concise Route to a Key Intermediate in the Total Synthesis of Sempervirine1

Enantiopure γ-amino and γ-hydroxy-β-ketosulfones have been synthesized in high yields from α-diazoketones derived from the α-amino and α-hydroxy acid chiral pools.     

Synthesis of the Ziegler Key Intermediate and Related Precursors for the Synthesis of Forskolin and Erigerol in Enantiomerically Pure Form

The Ziegler key intermediate 5, previously used in three total synthesis of forskolin (1), and the intermediate 4, potentially useful for the synthesis of erigerol (2), were obtained in optically pure form by the resolution of the allylic alcohol 7a with R-(-)-O-methylmandelic acid.     

Practical and Efficient Route to Dolutegravir Sodium via One-Pot Synthesis of Key Intermediate with Controlled Formation of Impurities

Russian Journal of Organic Chemistry - An efficient, cost effective and commercially viable synthesis of dolutegravir sodium has been developed from commercially available methyl...     

PBr3-DMF Assisted Elimination of a Highly Hindered Diallylic Tertiary Alcohol in a Bicyclic System: Synthesis of a Key Intermediate Useful for the Total Synthesis of Forskolin

Regioisomeric acetates 12 and 13. obtained by the PBr₃-DMF reaction on a highly hindered diallylic tertiary alcohol, were converted into a key intermediate 15. useful for the total synthesis of forskolin 1     

A Convenient Route to Norpyrenophorin

A norpyrenophorin precursor has been achieved by a three-step synthesis in good yield.     

Diazepinomicin关键中间体三甲氧基二苯二氮平的合成

以2,4-二甲氧基苯胺和3-甲基苯酚为原料,通过氨基保护、硝化、还原、甲基氧化、乌尔曼反应、内酰胺环化制得天然化合物Diazepinomicin的关键中间体——三甲氧基二苯二氮平,其结构经1H NMR,IR和MS表征.     

A New Approach to the Synthesis of A Key Intermediate in the Synthesis of Lincomycin

6-acetamido-6,8-dideox-1,2:3,4-di-O-isopropylidene- D -glycero-α-D-galacto-octopyranos-7-ulose (6), has been synthesised from D -galactose. The side chain elongation was carried out by cyano-amination of the protected dialdo sugar (2), followed by N-acetylation, and a subsequent Grignard reaction.     

A Convenient Route to Mixed Pnictogenylboranes

We report on the synthesis and characterization of mixed pnictogenylboranes. The substitution of the Lewis base SMe₂ in (OC)₅W–PH₂BH₂–SMe₂ ( 2 ) by different pnictogenylboranes ER₂BH₂–LB (E=P, As, Sb) leads to the Lewis acid/base stabilized butane analogue (OC)₅W–PH₂BH₂ER₂BH₂–LB ( 3 a , b : E=P; R=H, SiMe₃; LB=NMe₃; 4 a , b : E=As; R=H, SiMe₃; LB=NMe₃; 5 : E=Sb; R=SiMe₃; LB=NHC^Me). All of these compounds were characterized by single‐crystal X‐ray structure analysis, mass spectrometry, NMR, and IR spectroscopy. In addition, the very unstable phosphanylborane chain PH₂BH₂PH₂BH₂–NMe₃ ( 1 ) was synthesized. DFT calculations provide insight into the thermodynamics of these reactions.     

A Convenient Route for the Synthesis of 4-Aryl- and 4-Aminopyrimidines

Summary. A series of ureidopropenenitriles were synthesised by Knoevenagel condensation of ArCOCH₂CN and HC(OEt)₃ in presence of ureas in a one pot reaction. These ureidopropenenitriles were cyclised to 4-aryl-5-cyano-3-substituted pyrimidines (in acid) or to 4-amino-5-benzoylpyrimidines (in base) in 60–70% yields. The amine pyrimidine derivatives were further converted to substituted uracils by hydrolysis with isopentyl nitrite in DMF. Alkylation of uracils furnished 1,3-dimethyluracil derivatives with DMS in alkali. All new compounds were characterised by spectral and analytical methods.     

A Convenient Route for the Synthesis of 4-Aryl- and 4-Aminopyrimidines

A series of ureidopropenenitriles were synthesised by Knoevenagel condensation of ArCOCH₂CN and HC(OEt)₃ in presence of ureas in a one pot reaction. These ureidopropenenitriles were cyclised to 4-aryl-5-cyano-3-substituted pyrimidines (in acid) or to 4-amino-5-benzoylpyrimidines (in base) in 60–70% yields. The amine pyrimidine derivatives were further converted to substituted uracils by hydrolysis with isopentyl nitrite in DMF. Alkylation of uracils furnished 1,3-dimethyluracil derivatives with DMS in alkali. All new compounds were characterised by spectral and analytical methods.     

A Convenient Route to Substituted Thiocarbamides

A varicty of substituted thioureas result from thiuram disufides by a simple reaction with different amines.     

2H-苯骈吡喃类化合物的简便合成方法

2 H-苯骈吡喃(2 H-1-benzopyranes,1)又称色烯(chrom-3-ene),是一类天然有机化合物的基本骨架。许多包烯类化合物具有生物活性和光致变色效应,因此它们的合成方法一直是合成化学家感兴趣的课题。本文报道一种简便合成2 H-苯骈吡喃基本骨架的新方法,并用此法合成了从 Ageratum 属植物中分离得到的2,2-二甲基-6,7-二甲氧基苯骈吡喃(2)。     

Convenient Synthesis of 2-Allyl-3-bromo-1,4-dimethoxynaphthalene: Key Intermediate as Building Block for Bioactive Pyranonaphthoquinones

Synthesis of a key precursor 2-allyl-3-bromo-1,4-dimethoxynaphthalene (1) used in constructing various naturally occurring biologically active pyranonaphthoquinones is carried out utilizing easily available 1-methoxynaphthalene as a starting material. The synthesis was accomplished with Dakin's oxidation and Claisen rearrangement, thereby providing another easy approach toward (1) without involving highly lachrymatric 2-bromonaphthoquinone.     

Efficient Preparation of the Key Intermediate in Corey's Tamiflu Synthesis

A very efficient two‐step synthesis was developed to prepare the key intermediate in Corey's Tamiflu synthesis. DBU (1,8‐diazabicyclo[5.4.0] undec‐7‐ene) was used as a multifunctional catalyst for a series of reactions in a one pot procedure. The new synthesis was featured by the good availability of the starting material and the ease of the synthetic steps. This method might be practical for large scale preparations.     

Nickel-Catalyzed Asymmetric Hydrogenation for the Synthesis of a Key Intermediate of Sitagliptin

Nickel-catalyzed enantioselective hydrogenation of enamines leading to the efficient synthesis of 3-R-Boc-amino-4-(2,4,5-trifluorophenyl)butyric esters, the key intermediate of the blockbuster antidiabetic drug (R)-SITAGLIPTIN, is described. The sitagliptin motifs were isolated in more than 99% yield and with 75–92% ee using the earth-abundant nickel catalyst. Upon chiral resolution with (R)- and (S)-1-phenylethylamines, the partially enantioenriched (R)- and (S)-Boc-3-amino-4-(2,4,5-trifluorophenyl)butanoic acids provided >99.5% ee of the crucial sitagliptin intermediate. The asymmetric hydrogenation protocol was scaled up to 10 g with consistency in yield and ee, and has been reproduced in multiple batches.     

A Convenient Route to Condensed-Ring Aromatic Acetylenes

Palladium catalysed coupling of aryl halides with 3-methylbut-1-yn-3-ol and a subsequent base-induced retro-Favorsky reaction gave the corresponding ethynyl aromatics in good to excellent yields.