The Catalytic Asymmetric Aminohydroxylation of Unsaturated Phosphonates

The Catalytic Asymmetric Aminohydroxylation of Unsaturated Phosphonate

An Intramolecular [2 + 3] Cycloaddition Route to Fused 5-Heterosubstituted Tetrazoles

Fused 5-heterotetrazole ring systems are synthesized in high yield via intramolecular [2 + 3] cycloadditions of organic azides and heteroatom-substituted nitriles. Cyanates, thiocyanates, and cyanamides are all competent dipolarophiles for this reaction. A variety of scaffolds are tolerated when the new enclosed ring is five- or six-membered

Bis(trimethylsilyl) Peroxide Extends the Range of Oxorhenium Catalysts for Olefin Epoxidation

Bis(trimethylsilyl) Peroxide Extends the Range of Oxorhenium Catalysts for Olefin Epoxidatio

Applications of Aziridinium Ions. Selective Syntheses of β-Aryl-α,β-diamino Esters

α,β-Diamino esters are readily prepared through stereospecific and regioselective opening of an aziridinium ion intermediate with a variety of amines. The aziridinium ion is generated from the epoxide in two steps

An Expedient Route to the Tetrazole Analogues of α-Amino Acids

Convenient conditions are described for the transformation of α-aminonitriles to the tetrazole analogues of α-amino acids. Refluxing the starting material in water/2-propanol at 80 °C with sodium azide and catalytic zinc bromide affords the tetrazole product in yields generally exceeding 90%

Applications of Aziridinium Ions. Selective Syntheses of α,β-Diamino Esters, α-Sulfanyl-β-amino Esters, β-Lactams, and 1,5-Benzodiazepin-2-one

A variety of nucleophiles, including amines, thiolates, and alkoxides, were employed to open the aziridinium ions Az. The latter are opened stereospecifically and regioselectively at the C-3 position by a wide range of amines, and thiolate nucleophiles attack predominately at the C-2 position. Poor regioselectivities (ca. 1:1) were observed using nucleophiles derived from phenols, carboxylic acids, and imides. Base-mediated ring closure of the aziridinium opening products, from primary amines, gave β-lactams and a 1,5-benzodiazepin-2-one in high yields

A Simple Method for the Preparation of <i>N</i>-Sulfonylsulfilimines from Sulfides^†

While excellent methods exist for the oxidation of sulfides to sulfoxides R1R2S → R1R2SO, the aza-version of this atom transfer redox process, i.e., R1R2S → R1R2SN−SO2R3, has been less reliable. In sulfilimine synthesis, sulfoxide has been an inevitable byproduct in all cases to date, and the yields of sulfilimine have varied widely. A nearly ideal procedure for the sulfide to sulfonyl sulfilimine transformation is described. Almost quantitative yields are achieved from a diverse set of sulfides and a broad range of the readily available sulfonyl nitrenoid sources known as chloramine salts (R3SO2NClNa), essentially by simply stirring them together in acetonitrile

Preparation of 5-Substituted 1<i>H</i>-Tetrazoles from Nitriles in Water^†

The addition of sodium azide to nitriles to give 1H-tetrazoles is shown to proceed readily in water with zinc salts as catalysts. The scope of the reaction is quite broad; a variety of aromatic nitriles, activated and unactivated alkyl nitriles, substituted vinyl nitriles, thiocyanates, and cyanamides have all been shown to be viable substrates for this reaction

Ligand-Dependent Reversal of Facial Selectivity in the Asymmetric Dihydroxylation

Ligand-Dependent Reversal of Facial Selectivity in the Asymmetric Dihydroxylatio

Ethenesulfonyl Fluoride (ESF): An On-Water Procedure for the Kilogram-Scale Preparation

A two-step, on-water procedure for the synthesis of ethenesulfonyl fluoride (ESF) is described. 2-Chloroethanesulfonyl fluoride is made via a neat reaction with an aqueous, nearly saturated potassium bifluoride solution from readily available 2-chloroethanesulfonyl chloride. The subsequent dehydrochlorination of 2-chloroethanesulfonyl fluoride proceeds neatly with magnesium oxide as the base in an aqueous suspension to give ESF. This recipe allows the preparation of ESF in 98% yield on a kilogram scale