Practical Synthesis of Menthofuran

A 3-step synthesis of menthofuran from isopulegol in 65–70% is reported.     

Practical Synthesis of Aromatic Dithiocarbamates

Oxidation-sensitive N,N-diaryl dithiocarbamates (DTCs) are synthesized in good yields by the generation of metal amide salts from N-benzoyl precursors, followed by addition of CS₂. para-Substituted diphenylamines are prepared by electrophilic aromatic substitution of diphenylbenzamide and saponification. Deacylation of electron-rich species such as bis(p-dimethylaminophenyl)benzamide is challenging because of the oxidative sensitivity of the anionic intermediate but could be achieved in good yield by using n-BuLi to generate a hemiaminal adduct, prior to acidification. The N,N-diaryl DTCs are stable as alkali salts and can be used to produce densely packed monolayers on gold surfaces.     

Practical Synthesis of Sugar Monophosphonucleotides

A reliable procedure for the preparation of sugar nucleoside monophosphates is presented, which involves condensation of an activated glycosyl‐1‐H‐phosphonate with an appropriately protected nucleoside and simple end‐product isolation via lithium perchlorate–induced precipitation. The utility of these methods is demonstrated by the preparation of a number of purine‐ and pyrimidine‐based sugar nucleoside monophosphate derivatives.     

Practical Synthesis of Disaccharide H

Abstract

Oligosaccharide components of glycoconjugates play a fundamental role in recognition phenomena and intercellular interactions. Disaccharide H, 2-O-(α-L-fucopyranosyl)-D-galactopyranose, is one such biologically important, L-fucose containing oligosaccharide.¹ This disaccharide is found in natural antigenic determinants such as blood group determinants and tumor associated antigens.^1,2     

Practical Synthesis of N-Aryl-o-hydroxyaryl Ketimines

Heating o-hydroxyacetophenones and anilines under solvent-free conditions afforded the corresponding aryl ketimines in good to excellent yields.     

Practical Synthesis of (+)-Alloisoleucine

Subsequent treatment of N-crotoyl-(1S,2R)-bornane-10,2-sultam with EtMgCl, recrystallization of the product and saponification, afforded R-(-)-3-methylpenthanoic acid which was used for acylation of (1R,2S)-bornane-10,2-sultam. The product was converted into N-[(2S,3R)-2-amino-3-methylpentanoyl]-(1R,2S)-bornane-10,2-sultam by hydroxyamination with 1-chloro-1-nitrosocyclohexane, followed by reduction of the hydroxylamine grouping. Saponification of the sultam imide provided (+)-alloisoleucine.     

QM/MM Study on Enzymatic Mechanism in Sinigrin Biosynthesis

As the major and abundant type of glucosinolates (GL) in plants, sinigrin has potential functions in promoting health and insect defense. The final step in the biosynthesis of sinigrin core structure is highly representative in GL compounds, which corresponds to the process from 3-methylthiopropyl ds-GL to 3-methylthiopropyl GL catalyzed by sulfotransferase (SOT). However, due to the lack of the crystallographic structure of SOT complexed with the 3-methylthiopropyl GL, little is known about this sulfonation process. Fortunately, the crystal structure of SOT 18 from Arabidopsis thaliana (AtSOT18) containing the substance (sinigrin) similar to 3-methylthiopropyl GL has been determined. To understand the enzymatic mechanism, we employed molecular dynamics (MD) simulation and quantum mechanics combined with molecular mechanics (QM/MM) methods to study the conversion from ds-sinigrin to sinigrin catalyzed by AtSOT18. The calculated results demonstrate that the reaction occurs through a concerted dissociative mechanism. Moreover, Lys93, Thr96, Thr97, Tyr130, His155, and two enzyme peptide chains (Pro92-Lys93 and Gln95-Thr96-Thr97) play a role in positioning the substrates and promoting the catalytic reaction by stabilizing the transition state geometry. Particularly, His155 acts as a catalytic base while Lys93 acts as a catalytic acid in the reaction process. The presently proposed concerted dissociative mechanism explains the role of AtSOT18 in sinigrin biosynthesis, and could be instructive for the study of GL biosynthesis catalyzed by other SOTs.     

A Practical Synthesis of Tetrachloroethylene Oxide

Tetrachloroethylene oxide has been synthesized by direct oxidation of tetrachloroethylene with oxygen in the presence of ultraviolet light. This preparation resulted in a mixture of tetrachloroethylene oxide and trichloroacetyl chloride in approximately equal amounts under the most favorable conditions. Tetrachloroethylene oxide rearranges readily to trichloroacetyl chloride above 60 C with an activation energy E of 3.0 × 10⁴ cal/mole and a pre-exponential factor A of 1.9 × 10¹³. All attempts to polymerize tetrachloroethylene oxide under a variety of conditions failed.     

New and Practical Synthesis of Momelotinib

New and practical synthetic route of momelotinib, a JAK inhibitor, is described on a decagram scale. A convergent synthetic process is adopted to prepare the methyl 4‐(2‐((4‐morpholinophenyl)amino)pyrimidin‐4‐yl) benzoate intermediate, by cyclization of 1‐(4‐morpholinophenyl)guanidine and methyl 4‐(3‐(dimethylamino)acryloyl)benzoate in high yield and mild conditions. Momelotinib is obtained in 43.2% yield over five steps and 99.1% purity (HPLC).     

Selective and Practical Synthesis of Penciclovir

Abstract

A selective and practical method has been developed for the synthesis of penciclovir (1) in gram quantities involving a highly N ⁹ selective alykylation of 2-amino-6-chloropurine (9) with 2-(2-phenyl-1,3-dioxane-5-yl)ethanol (12) as a key step.     

Practical Synthesis of Structurally Important Spirodiamine Templates

A general, concise, four‐step synthetic sequence for the preparation of spirodiamine templates is described herein.     

3,13-二羟基-1,5,8,11,15,18-六氮杂环二十烷的合成研究

尝试了三种制备 3 ,13 二羟基 1,5 ,8,11,15 ,18 六氮杂环二十烷 ( 5 )的方法 .实验结果表明 1,3 二氯 2 丙醇 ( 1)与N 对甲苯磺酰基 -二乙烯三胺 ( 2 )在醇钠条件下制备 5的方法简便可行 ,易于纯化 ,收率较高     

A Practical Total Synthesis of Taxamairin B

Taxamairin B. a novel rearranged 9(10 ± 20)-abeo-8. 11. 13-triene diterpenoid. has been convergently synthesized by a facile route, which employed the acid catalyzed rearrangement and oxidation of vinyl carbinol as the key steps.     

New Practical Synthesis of Tetrahydronquinolin-2,5-diones

A series of 4,6,7,8-tetrahydro-2,5-(1H,3H)-quinolinediones was prepared from ethyl-2-cyanoacetate, aromatic aldehydes and 1,3-cyclohexanedione or 5,5-dimethyl-1,3-cyclohexanedione by two steps, the yields were moderate to excellent. This method is a new practical promising green strategy to synthesize tetrahydronquino-lin-2,5-diones.     

Practical Synthesis of Functionalized 2‐Thioxoimidazolidine Derivatives

High‐yielding syntheses of an unpublished series of 2‐thioxo‐imidazolidin‐4‐ones 6 bearing an N‐ethoxycarbonyl and amidyl moieties an N₁ and C₅, respectively, are reported. These derivatives were obtained by intramolecular cyclization of 3‐ethylhydrazinoacetate 3,4‐dihydro maleimides 4 in the presence of ethyl or phenylisothiocyanate 2 under neutral conditions.     

A Short and Practical Synthesis of 1-Deoxynojirimycin

The potent glucosidase inhibitor 1-deoxynojirimycin was synthesized from L-sorbose using a short synthesis and only one protecting group. The last step, which constituted the removal of an acetonide protecting group and an intramolecular reductive amination, was accomplished on an acidic lon-exchange resin. This provided a synthesis capable of being operated on a multi-kilogram scale.     

A Practical Synthesis of 6-Acetylsalicylic Acid Methyl Ester

A new and efficient synthesis of the title compound is reported. The method includes a regioselective ortho-lithiation step in none polar solvents at an ambient temperature and the overall yield for 5 steps is more than 70% from a commercially available 3-hydroxyacetophenone.