Efficient Synthesis of N-[(2-Hydroxyethoxy)methyl]-2-alkyl-3-hydroxy-4-pyridinone by a Modified Hilbert-Johnson Reaction

Ethyleneglycol derivatives of 2-methyl (and ethyl)-3-hydroxy-4-pyridinone were synthesized by a modified Hilbert-Johnson reaction. The synthesis proceedes by reaction of O-protected 2-alkyl-3-hydroxy-4-pyridinone with hexamethyldisilazane in the presence of chlorotrimethylsilane followed by trimethylsilyl trifluoromethanesulfonate catalized alkylation with benzyloxy-ethoxymethylchloride in dichloroethane and deprotection by hydrogenation. The overall yield was 87%. This method provides a useful way to produce oligo- or polyethyleneglycol substituted hydroxypyridinones.     

Conversion of Epoxides to β‐Chlorohydrins with Thionyl Chloride and β‐Cyclodextrin in Water

Several epoxides are efficiently converted to the corresponding β‐chlorohydrins in impressive yields with thionyl chloride in the presence of β‐cyclodextrin using water as solvent at room temperature.     

New Approach to 3‐Aminothiophene‐ 2‐carboxylic Acid Derivatives: Access to 5‐Aryl‐4‐(ethylsulfanyl) Compounds

Treatment of DMSO/water solutions of β‐bromo‐α‐(ethylsulfanyl)cinnamonitriles with sodium sulphide and α‐halo acetic acids derivatives followed by cyclization in a potassium carbonate/acetone/DMSO mixture gave the expected 3‐amino‐5‐aryl‐4‐(ethylsulfanyl)thiophene‐2‐carboxylic acids derivatives in fair yields.     

A Practical,One-Pot Preparation of Diisopinocampheylchloroborane

A one-pot preparation of the chiral reducing agent diisopinocampheylchloroborane (Ipc₂BCl) from α-pinene and borane methyl sulfide has been developed. The procedure obviates isolation of the air and moisture sensitive reagent, making it useful for large scale operations. Asymmetric reduction of ketones using the in situ prepared Ipc₂BCl is comparable to that using isolated reagent.     

Novel and Efficient Approach to Fluorinated β‐Aminobutanones Catalyzed by Molecular Iodine

A variety of fluorinated compounds of β‐amino ketones could be obtained in good to excellent yields at room temperature through a three‐component Mannich reaction of aldehydes, anilines, and acetones catalyzed by iodine.     

Facile and Efficient Synthesis of Substituted 1,4‐Dithiafulvalenes from β‐Dicarbonyl Compounds

A facile and efficient synthetic route to substituted 1,4‐dithiafulvalenes has been developed. The precursors 2 may be easily prepared from the reactions of β‐dicarbonyl compounds 1 with CS₂ and 1,2,3‐tribromopropane under mild conditions. The elimination of HBr of 2 in basic media furnishes corresponding acetyl substituted 1,4‐dithiafulvalenes 3 in 85–93% yields. The aldol condensation reaction of 2 with various arylaldehydes affords alkenoyl substituted 1,4‐dithiofulvalenes 4 in high to excellent yields.     

Efficient Synthesis of β‐Amino Alcohols Catalyzed by Niobium Pentachloride: Regioselective Ring Opening of Epoxides with Aromatic Amines

Epoxides undergo a rapid ring‐opening reaction with aromatic amines catalyzed by niobium pentachloride under mild reaction conditions. All the reactions were carried out at room temperature to afford the corresponding β‐amino alcohols in excellent yields and with high regioselectivity.     

Efficient Regioselective Ring Opening of Oxiranes with Thioacids in the Presence of β‐Cyclodextrin in Water

A mild and convenient synthesis of β‐hydroxy thioesters has been achieved by the regioselective ring opening of oxiranes using thioacetic acid and thiobenzoic acid in the presence of β‐cyclodextrin in water at room temperature. β‐Hydroxy thioesters are realized in high yields, and β‐cyclodextrin can also be recovered and reused.     

Efficient Synthesis of Tetrahydrobenzo[b]pyrans under Solvent‐Free Conditions at Room Temperature

A range of tetrahydrobenzo[b]pyrans have been synthesized in very good yields under solvent‐free conditions by grinding α‐cyanocinnamonitrils or β‐cyano‐β‐carbethoxy styrene and 5,5‐dimethyl‐1,3‐cyclohexanedione in the presence of TEBA as catalyst. The short reaction time, cleaner reaction, and easy workup make this protocol practical and economically attractive.     

Unexpected Rearrangement in the Reaction of 7‐Mercapto‐4‐methylcoumarin with 1‐Mono‐ and 1,1‐Dimethyl Propargyl Alcohols

The reaction of 7‐mercapto‐4‐methylcoumarin (4) with 1‐mono‐ and 1,1‐dimethyl propargyl alcohols in H₃PO₄ afforded the corresponding β‐(7‐coumarinthio)ketones with a rearrangement of the carbon chain of propargyl. A possible mechanism of this rearrangement was proposed.