Domingo Gomez Pardo

Ring Expansion – Formation of Optically Active 3‐Hydroxypiperidines from Pyrrolidinemethanol Derivatives

Treatment of pyrrolidinemethanol derivatives (–)-1, (–)-6, (–)-7, 8, (–)-9, (+)-10, (–)-11, and (–)-21 with trifluoroacetic anhydride and then with Et3N afforded, after hydrolysis of the trifluoroacetyl group with NaOH, the optically active 3-hydroxypiperidines (–)-14, (+)-15, (–)-16, 17, (+)-18, (–)-19, (–)-20, and (+)-22, respectively. The yields are good and the enantiomeric excess excellent (up to 95 %).

Formation of optically active 3-hydroxypiperidines

Abstract The synthesis of enantiomerically pure 3-hydroxypiperidines has been achieved from prolinol.

Synthesis of Aryl Sulfides: Metal-Free C-H Sulfenylation of Electron-Rich Arenes.

A simple, efficient, and practical metal-free C-H sulfenylation of substituted electron-rich arenes has been developed. This method is highly regioselective, and the corresponding aryl sulfides were obtained in moderate to excellent yields from stable and readily accessible N-(alkylthio)- and N-(arylthio)succinimides at room temperature in the presence of TFA.

Monoalkylation of acetonitrile by primary alcohols catalyzed by iridium complexes.

The monoalkylation of acetonitrile by primary alcohols was achieved in a one-pot sequence in the presence of iridium catalysts. A diversity of nitriles has been obtained from aryl- and alkyl-methanols in excellent yield.

Daucus carota Mediated-Reduction of Cyclic 3-Oxo-amines

Carrots (Daucus carota) were used to reduce cyclic amino-ketones in high yields and enantiomeric excesses. This cheap, eco-compatible, and efficient reducing reagent allows the easy access to precursors of biologically active products.

Iridium-catalyzed hydrogen transfer: synthesis of substituted benzofurans, benzothiophenes, and indoles from benzyl alcohols.

An iridium-catalyzed hydrogen transfer has been developed in the presence of p-benzoquinone, allowing the synthesis of a diversity of substituted benzofurans, benzothiophenes, and indoles from substituted benzylic alcohols.

A CONVENIENT ROUTE TO SPIROPYRROLIDINYL-OXINDOLE ALKALOIDS VIA C-3 SUBSTITUTED ENE-PYRROLIDINE CARBAMATE RADICAL CYCLIZATION

Abstract A short access to spiropyrrolidinyl-oxindole alkaloids via a substituted ene-pyrrolidine carbamate, synthesized from the commercially available tert -butyl 1-pyrrolidine carboxylate, is described.

Ring Expansion of Cyclic β-Amino Alcohols Induced by Diethylaminosulfur Trifluoride: Synthesis of Cyclic Amines with a Tertiary Fluorine at C3

As the replacement of a hydrogen atom by a fluorine atom in a compound can have an important impact on its biological properties, the development of methods allowing the introduction of a fluorine atom is of great importance. The scope and limitations of the ring expansion of cyclic 2-hydroxymethyl amines induced by diethylaminosulfur trifluoride (DAST) to produce cyclic β-fluoro amines was studied as well as the enantioselectivity of the process.

Access to optically active 3-azido- and 3-aminopiperidine derivatives by enantioselective ring expansion of prolinols.

The activation of N-alkyl prolinols by XtalFluor E allowed the formation of an aziridinium intermediate that can react with tetrabutylammonium azide (nBu(4)NN(3)) to produce 3-azidopiperidines and/or 2-(azidomethyl)pyrrolidines, in a ratio up to 100/0. These 3-azidopiperidines can be reduced to the corresponding 3-aminopiperidines.

A new nitrone from C2 symmetric piperidine for the synthesis of hydroxylated indolizidinone

Abstract The oxidation of a C 2 symmetric piperidine, obtained through a ring enlargement process of the enantiopure protected (4 R )-hydroxy-(2 S )-hydroxymethyl pyrrolidine, is reported. Oxidation with C -phenyl- N -phenylsulfonyloxaziridine afforded the corresponding nitrone that is too unstable for isolation and which reacted in situ with dimethyl maleate. The major adduct was transformed to the corresponding protected dihydroxyindolizidinone.