Convenient Method for Synthesis of Substituted 2‐Amino‐2‐chromenes

Some substituted 2‐amino‐2‐chromenes were synthesized by the reaction of arylidenemalononitriles with 1‐naphthol or 2‐naphthol in the presence of sodium hydroxide as catalyst under solvent‐free condition.     

Convenient Synthesis of 3,5‐Disubstituted Isoxazoles

α,β‐Unsaturated oximes obtained from the corresponding α,β‐unsaturated ketones on treatment with 2 equivalents of manganese dioxide in refluxing chloroform gives 3,5‐disubstituted isoxazoles in good yields.     

Convenient Synthesis of 5‐Aryl Uracils

A convenient one‐step synthesis of 5‐aryl uracils has been developed. The procedure involves heating ethyl 3‐hydroxy‐2‐arylpropenate with urea at 130°C, followed by base‐catalyzed cyclization. The method is simple and high yielding.     

Convenient Synthesis of Some Substituted 5‐Oxonitriles under Aqueous Conditions: Synthesis of 3,4‐Dihydro‐2H‐pyrrole‐2‐carbonitriles

Michael additions of [(diphenylmethylene)amino]acetonitrile (1) to α,β‐unsaturated ketones (chalkones) (2) under aqueous conditions allow for the highly diastereoselective synthesis of substituted 2‐amino‐5‐oxonitriles (3). Selective removal of diphenylmethylene protecting group, followed by in situ cyclization, gives 3,5‐diaryl‐3,4‐dihydro‐2H‐pyrrole‐2‐carbonitriles (4).     

Facile and Convenient Synthesis of 1‐Perfluoroalkyl‐1,2,4‐triazoles

Treatment of N‐methylcarbonyl 1, N‐phenylthioamido 2, and N‐cyano 3 iminoethers with perfluoroalkylated hydrazines leads to 1‐perfluoroalkyl‐5‐methyl‐1,2,4‐ triazoles, 4,1‐perfluoroalkyl‐5‐phenylamino‐1,2,4‐triazoles 5, and 1‐perfluoroalkyl‐5‐amino‐1,2,4‐triazoles 6 in good yields. These compounds are screened for their biological activities.     

Convenient One‐Pot Synthesis of Vinyl Ethers from Phenyl 2‐Hydroxyalkyl Selenides

Vinyl ethers were prepared with good yields in a one‐pot, two‐step transformation by O‐alkylation reaction of phenyl 2‐hydroxyalkyl selenides with primary or secondary organic halides followed by oxidation elimination with 30% hydrogen peroxide.     

Convenient Large‐Scale Synthesis of Universal Solid Support

A simple, convenient large‐scale synthesis of a universal solid support useful for the synthesis of oligonucleotides is described.     

Convenient Formal Synthesis of (±)‐Paroxetine

A formal total synthesis of antidepressant (±)‐paroxetine employing a solvent‐free Heck reaction is disclosed.     

Convenient and Regioselective One‐Pot Solvent‐Free Synthesis of ß‐Hydroxyphosphonates

A simple, efficient, regioselective, and solvent‐free method has been developed for the synthesis of β‐hydroxyphosphonates from epoxides and triethyl phosphite using ZnCl₂ in high yields under mild conditions.     

Convenient Synthesis of Structurally Novel 1,3‐Disubstituted Azetidine Derivatives

A convenient synthesis of structurally novel 1,3‐disubstituted azetidine derivatives is described. The approach involves condensation of an azetidine building block with sulfonylated carbamic acid methyl ester, subsequently followed by quenching the imidoyl chloride with amines. Different derivatives were prepared by substituting benzhydrol as well as benzenesulfonamide as part of the core structure.     

Convenient Synthesis of Tolcapone,a Selective Catechol‐O‐methyltransferase Inhibitor

A convenient and efficient synthesis of tolcapone from commercial 4‐benzyloxy‐3‐methoxybenzaldehyde is presented. Grignard reaction of 4‐benzyloxy‐3‐methoxybenzaldehyde (1) with p‐tolylmagnesium bromide followed by Oppenauer oxidation of the hydroxyl functionality and subsequent O‐debenzylation gave phenol 5. Compound 5 was regioselectively nitrated and then subjected to O‐demethylation to produce tolcapone in 60% overall yield.     

Simple and Convenient Synthesis of 21‐Thioalkylether Derivatives of Methyl 16‐Prednisolone Carboxylates

The antedrug approach for corticosteroids has been described as a fundamentally sound approach for the development of safer anti‐inflammatory and anti‐asthmatic therapy. However, the derivatization of prednisolone and its congeners have been considered to be major pitfalls, because their syntheses are complicated by the presence of numerous carboxylate esters and hydroxyl functions in the steroid nucleus. A simple and direct synthesis of 21‐thioalkylether derivatives of methyl 16‐prednisolonecarboxylates is described. The 21‐mesylate of the methyl 16‐prednisolonecarboxylate and 9‐fluoro‐17‐dehydro methyl 16‐prednisolonecarboxylate were reacted with Na‐thioalkoxides to furnish the desired thioethers in good yields. A previously published method for the methanolysis of 16‐cyanoprednisolone to methylcarboxylate has been reexamined, and the conditions are explained clearly. The reaction conditions for all these reactions were critical.     

Convenient Synthesis of Pyrrole‐ and Indolecarboxylic Acid tert‐Butylesters

Abstract

The tert‐butylesters of pyrrole‐ and indolecarboxylic acids are readily accessed by reacting the appropriate carboxylic acids with N,N‐dimethylformamide di‐tert‐butyl acetal.     

Efficient and Convenient One‐Pot Synthesis of Phosphoramidates and Phosphates

A simple and efficient one‐pot method is described for the synthesis of phosphoramidates/phosphates in excellent yields from dialkylphosphites and trichloroisocyanuric acid in acetonitrile and subsequent treatment with dialkyl amines/alcohols. The procedure is operationally simple, has reduced reaction times, and uses a one‐pot procedure.     

Simple and Convenient Synthesis of 4‐Unsubstituted‐3‐(3‐Oxoalkyl)isocoumarins

A simple transformation of 2‐alkylfurans and 2‐formylbenzoic acids into 4‐unsubstituted 3‐(3‐oxoalkyl)isocoumarins is described. It is based on the synthesis of 2‐(2‐carboxybenzyl)furans followed by their acid‐catalyzed recyclization to the target isocoumarins.     

A Convenient Synthesis of N‐Boc‐Protected α‐Aminonitriles from α‐Amidosulfones

Abstract

Synthesis of N‐Boc‐protected α‐aminonitriles starting from N‐Boc‐protected α‐aminosulfones is described. Treatment of the sulfone with two equivalents of potassium cyanide in 2‐propanol or dichloromethane‐H₂O under phase transfer condition affords crystalline N‐Boc‐protected α‐aminonitriles in good yield. Hydrolysis of the aminonitriles provides a convenient access to racemic α‐amino acids.     

A Convenient and Efficient Preparation of 2‐Acetyl‐4,5‐difluorothiophene

A convenient, five‐step preparation of 2‐acetyl‐4,5‐difluorothiophene from 2,3‐dibromothiophene is described.     

Convenient One‐Pot Procedures for the Synthesis of 2,2′:6′,2″‐Terpyridine

One‐pot reactions to produce 2,2′:6′,2″‐terpyridine (tpy) under mild conditions are described under both solventless and solvent‐assisted conditions. Tpy can be obtained in 32% yield in a simple one‐pot reaction, which can readily be scaled‐up to give large quantities of tpy. These new approaches are superior to those previously described because of the fast and efficient synthesis and purification of tpy.     

Convenient Synthesis and Reactivity of Ethyl 8‐amino‐6‐methyl‐2,3‐dihydro‐4H‐1‐benzopyran‐2‐carboxylate

Abstract

We report and comprehensively describe the synthesis and reactivity of ethyl 8‐amino‐6‐methyl‐3,4‐dihydro‐2H‐1‐benzopyran‐2‐carboxylate. This peptidomimetic building block provides a constrained template that allows for the introduction of various functionalities in a specific spatial orientation.     

Convenient Synthesis of Nucleoside‐5′‐Diphosphates from the Corresponding Ribonucleoside‐5′‐phosphoroimidazole

The reaction of ribonucleoside‐5′‐phosphoroimidazolide with a tributylammonium orthophosphate in anhydrous dimethylformamide at room temperature provides a general method for the synthesis of nucleoside‐5′‐diphosphates. The novelty of the approach is to use the triethylammonium salt of 5′‐monophosphate nucleoside derivative prior to the imidazolate reaction with imidazole, triphenylphosphine, and 2,2′‐dithiodipyridine. Deprotection, followed by displacement of the imidazole moiety using tributylammonium orthophosphate and a catalytic amount of zinc chloride in dimethylformamide gave the desired 5′‐diphosphate products. The triethyl ammonium salt of 5′‐diphosphate nucleosides was purified by flash chromatography using DEAE (diethylaminoethyl weak anion exchange resin) Sepharosa fast flow packed in an XK 50/60 column on an Akta FPLC (Fast Protein Liquid Chromatography). Synthesis procedures are reported for adenosine‐5′‐diphosphate, uridine‐5′‐diphosphate, cytidine‐5′‐diphosphate, and guanosine‐5′‐diphosphate. Yields for the displacement reactions ranged from 95 to 97%. Thus, this method offers the advantages of shorter reaction time, greater product yield, and a more cost‐effective synthetic route.