An efficient and convenient synthesis of unsymmetrical disulfides from thioacetates

We have developed convenient methods for the synthesis of functionalized unsymmetrical dialkyl disulfides under mild conditions in very good yields. The designed method is based on the reaction of (5,5-dimethyl-2-thioxo-1,3,2-dioxaphosphorinan-2-yl)-disulfanyl derivatives 1 with functionalized alkyl thiolate anions, generated in situ from thioacetates 2 and sodium methoxide or butylamine. The developed method allows the preparation of unsymmetrical disulfides bearing additional hydroxy, carboxy, amino, azido, biotin, or maleimide functionalities.     

Regiospecific and stereoselective conversion of ribonucleosides to 3′-deoxynucleosides. A high yield three-stage synthesis of cordycepin from adenosine.

Treatment of 2′,3′-anhydroadenosine (obtained² in 92% yield from adenosine) with lithium triethylborohydride (or deuteride) gave cordycepin (or its 3′($\text{R}$)-deuterio derivative) in ≈90% overall yields with no 2′-deoxy isomer detected.     

An expeditious and convenient synthesis of acylsulfonamides utilizing polymer-supported reagents

Acylsulfonamides can be rapidly and conveniently synthesized from a variety of carboxylic acids and sulfonamides utilizing the commercially available reagents, PS-DCC and DMAP under mild reaction conditions. DMAP can be efficiently scavenged by utilization of a silica-supported tosic acid cartridge (Si-SCX). In most of the cases studied, products with high purities and yields were obtained without the need for further purification.     

An effective synthesis of medium-ring ketones

Medium-ring ketones (8–12 membered ketones) were synthesized based on the intramolecular cyclization of large-ring lactam sulfoxides or sulfones.     

An efficient and convenient approach to the total synthesis of sphingofungin

As a new member of the sphingofungin family, sphingofungin F exhibits interesting physiological activities with a structural unit of an alpha-substituted alanine. Described herein is an efficient and convenient stereoselective synthesis of sphingofungin F from L-(+)-tartaric acid, which utilizes Sharpless asymmetric epoxidation of allylic alcohol and Lewis acid-catalyzed intramolecular epoxide-opening reaction with an N-nucleophile, to introduce the other two desired stereogenic centers. Side chain functionality was incorporated into the chiral segment using a Wittig reaction.     

A convenient synthesis of O-alkyl thioesters from esters

O-Alkyl thioesters may be prepared from the corresponding carboxylic esters by successive treatment with lithium diisopropylamide, chlorotrimethylsilane, and hydrogen sulfide.     

New convenient synthesis of iridol. An approach to the synthesis of ubiquinones

A strategy for the synthesis of ubiquinones, in which iridol is the key intermediate, has been developed, together with a new convenient synthesis of iridol (2,3-dimethoxy-5-methylphenol) starting from the easily available 4-methylphenol and using mild conditions and friendly and high-yielding reactions.     

蛹虫草及其培养残基中腺苷和虫草素含量的快速测定

建立了以氰基正相色谱柱反相条件下快速分析腺苷和虫草素的方法。以微波辅助提取蛹虫草及其培养残基样品,每次提取1.5 min,共提取2次。采用Eclipse XDB-CN色谱柱测定提取液中腺苷和虫草素的含量,以甲醇-水(7:93, v/v)为流动相进行等度洗脱,检测波长260 nm,并考察和分析了影响分离性能的流动相组成和pH值。结果腺苷和虫草素在4.5 min内实现完全分离且无基质干扰。腺苷和虫草素在线性范围内线性关系良好,线性相关系数r2分别为0.9998和0.9995,定量限(以10倍信噪比计)分别为0.21 mg/L(腺苷)和0.083 mg/L(虫草素)。该方法日内和日间精密度的相对标准偏差(RSD)小于2%;腺苷和虫草素的平均加标回收率为93.8%～102.9%, RSD值不大于3.62%(n=5)。本方法简便、快速、准确、成本低,可用于冬虫夏草、蛹虫草子实体、虫草培养残基及虫草制剂中腺苷和虫草素含量的快速测定。     

An efficient and convenient synthesis of pentasubstituted pyrroles from alkyl acetoacetates,dialkyl acetylenedicarboxylates,and amines

A simple and efficient synthesis of pentasubstituted pyrroles has been developed using a one-pot, two-step reaction. The synthesis of a series of 4-hydroxypenta-1,3-diene-tricarboxylates from alkyl acetoacetates and dialkyl acetylenedicarboxylates in the presence of K₂CO₃, followed by cyclization with amines, gave the corresponding pyrroles in excellent yields.     

A convenient one-pot synthesis of boroxoles from diboronic acid

The preparation of the boroxole motif traditionally relies on a 3-step process and the use of n-butyl lithium that can limit substrate scope. Herein during our exploration toward novel RORγ inhibitors, we identified a convenient one-pot preparation of the motif in good yields with good substrate scope.     

A convenient synthesis of 1-aminophosphonates from 1-hydroxyphosphonates

A simple, efficient, and general method has been developed for the synthesis of 1-aminophosphonates from 1-hydroxyphosphonates under solvent-free conditions using microwave irradiation. 1-Aminophosphonates were obtained in high yield and mild conditions by reaction of diethyl 1-hydroxyalkylphosphonates with amines in the presence of acidic alumina.     

A convenient one-pot two-step synthesis of pyrazolylphosphonates from ethynylphosphonate

A convenient one-pot preparation of pyrazol-3-ylphosphonates involves Cu-catalyzed cross-coupling of acyl chlorides with diethyl ethynylphosphonate followed by heterocyclization with hydrazine.     

A convenient synthesis of nicotinate esters from 3-cyanopyridones

A convenient synthesis of alkyl-substituted ethyl nicotinates 8 was devised, using 3-cyano-2(1H)-pyridones 4. These were converted to the corresponding 2-bromo-3-cyanopyridines 5 with boiling phosphorus tribromide. The resulting 5 were smoothly debrominated to 3-cyanopyridines 6 with zinc dust in boiling ethanolic acetic acid. The nitrile function was hydrolyzed in boiling 6N hydrochloric acid, and the resulting nicotinic acid hydrochlorides 7 esterified with refluxing triethyl orthoformate, to give the ethyl nicotinates 8. A modified formylation of 2-butanone led to the sodium salt of 2-methyl-3-oxobutanal ( 3a ) of enhanced purity.     

A convenient synthesis of new heterocycles from benzimidazoles and carbon suboxide

The reaction of carbon suboxide with 2-substituted benzimidazoles was investigated. By this reaction 1,3-diazino- (pyrimido-), 1,3-oxazino- and 1,3-thiazinobenzimidazole-1,3-diones are obtained.     

Tereoselective total synthesis of racemic grandisol : An improved convenient procedure

(±) Grandisol has been stereoselectively synthesized in a 31% overall yield by a practical and convenient procedure employing the Salomon photobicyclization as the key-step.     

A convenient synthesis of dihydrocoumarins from phenols and cinnamic acid derivatives

A facile procedure for synthesis of dihydrocoumarin derivatives was described. Although the yield of the products in the reaction of phenols with acrylates in trifluoroacetic acid in the presence of Pd(OAc)₂ giving coumarins was found to be very low, dihydrocoumarin derivatives were obtained in good to high yields in the absence of Pd(OAc)₂ when ethyl cinnamates bearing electron-donating groups were employed in this reaction.