Synthesis of quinoline-3-carboxylates by a Rh(II)-catalyzed cyclopropanation-ring expansion reaction of indoles with halodiazoacetates

Abstract In this letter, we report a novel synthesis of ethyl quinoline-3-carboxylates from reactions between a series of indoles and halodiazoacetates. The formation of the quinoline structure is probably the result of a cyclopropanation at the 2-and 3-positions of the indole followed by ring-opening of the cyclopropane and elimination of H-X. 194

α-Bromodiazoacetamides – a new class of diazo compounds for catalyst-free, ambient temperature intramolecular C–H insertion reactions

In this work, we introduce a new class of halodiazocarbonyl compounds, α-halodiazoacetamides, which through a metal-free, ambient-temperature thermolysis perform intramolecular C–H insertions to produce α-halo-β-lactams. When carried out with α-bromodiazoacetamides bearing cyclic side chains, the thermolysis reaction affords bicyclic α-halo-β-lactams, in some cases in excellent yields, depending on the ring size and substitution pattern of the cyclic amide side chains

Synthesis of quinoline-3-carboxylates by a Rh(II)-catalyzed cyclopropanation-ring expansion reaction of indoles with halodiazoacetates

In this letter, we report a novel synthesis of ethyl quinoline-3-carboxylates from reactions between a series of indoles and halodiazoacetates. The formation of the quinoline structure is probably the result of a cyclopropanation at the 2- and 3-positions of the indole followed by ring-opening of the cyclopropane and elimination of H–X

On the cause of low thermal stability of ethyl halodiazoacetates

Abstract Rates for the thermal decomposition of ethyl halodiazoacetates (halo = Cl, Br, I) have been obtained, and reported herein are their half-lives. The experimental results are supported by DFT calculations, and we provide a possible explanation for the reduced thermal stability of ethyl halodiazoacetates compared to ethyl diazoacetate and for the relative decomposition rates between the chloro, bromo and iodo analogs. We have also briefly studied the thermal, non-catalytic cyclopropanation of styrenes and compared the results to the analogous Rh(II)-catalyzed reactions. 159

Cyclopropanation–ring expansion of 3-chloroindoles with α-halodiazoacetates: novel synthesis of 4-quinolone-3-carboxylic acid and norfloxacin

We present a short and efficient way of synthesizing two synthetically versatile 4-quinolone-3-carboxylate building blocks by cyclopropanation-ring expansion of 3-chloroindoles with α-halodiazoacetates as the key step. This novel transformation was applied towards the synthesis of the antibiotic drug norfloxacin

Nucleophilic Halogenations of Diazo Compounds, a Complementary Principle for the Synthesis of Halodiazo Compounds: Experimental and Theoretical Studies

Three new protocols for the nucleophilic halogenations of diazoesters, diazophosphonates, and diazopiperidinylamides as complementary methods to our previously reported electrophilic halogenations are presented for the first time. On the basis of hypervalent α-aryliodonio diazo triflate salts <b>1A</b>, <b>2A</b>, and <b>3A</b>, the corresponding halodiazo compounds are generated via nucleophilic halogenations with tetrabutylammonium halides or potassium halides. The products from subsequent catalytic intermolecular cyclopropanations of the halodiazoesters and halodiazophosphonates and thermal intramolecular C–H insertion of the brominated diazopiperidinylamide are obtained in moderate to good yields after two steps. DFT calculations are presented for the diazoesters to give insight into the mechanism and transition states of the nucleophilic substitutions with the neutral nucleophiles dimethyl sulfide and triethylamine and the bromination with Br^–

Nucleophilic Halogenations of Diazo Compounds, a Complementary Principle for the Synthesis of Halodiazo Compounds: Experimental and Theoretical Studies

Three new protocols for the nucleophilic halogenations of diazoesters, diazophosphonates, and diazopiperidinylamides as complementary methods to our previously reported electrophilic halogenations are presented for the first time. On the basis of hypervalent α-aryliodonio diazo triflate salts <b>1A</b>, <b>2A</b>, and <b>3A</b>, the corresponding halodiazo compounds are generated via nucleophilic halogenations with tetrabutylammonium halides or potassium halides. The products from subsequent catalytic intermolecular cyclopropanations of the halodiazoesters and halodiazophosphonates and thermal intramolecular C–H insertion of the brominated diazopiperidinylamide are obtained in moderate to good yields after two steps. DFT calculations are presented for the diazoesters to give insight into the mechanism and transition states of the nucleophilic substitutions with the neutral nucleophiles dimethyl sulfide and triethylamine and the bromination with Br^–

Nucleophilic Halogenations of Diazo Compounds, a Complementary Principle for the Synthesis of Halodiazo Compounds: Experimental and Theoretical Studies

Three new protocols for the nucleophilic halogenations of diazoesters, diazophosphonates, and diazopiperidinylamides as complementary methods to our previously reported electrophilic halogenations are presented for the first time. On the basis of hypervalent α-aryliodonio diazo triflate salts <b>1A</b>, <b>2A</b>, and <b>3A</b>, the corresponding halodiazo compounds are generated via nucleophilic halogenations with tetrabutylammonium halides or potassium halides. The products from subsequent catalytic intermolecular cyclopropanations of the halodiazoesters and halodiazophosphonates and thermal intramolecular C–H insertion of the brominated diazopiperidinylamide are obtained in moderate to good yields after two steps. DFT calculations are presented for the diazoesters to give insight into the mechanism and transition states of the nucleophilic substitutions with the neutral nucleophiles dimethyl sulfide and triethylamine and the bromination with Br^–

Asymmetric Organocatalytic Aldol Reaction in Water: Mechanistic Insights and Development of a Semi-Continuously Operating Process

Rulli G, Fredriksen KA, Duangdee N, Bonge-Hansen T, Berkessel A, Gröger H. Asymmetric Organocatalytic Aldol Reaction in Water: Mechanistic Insights and Development of a Semi-Continuously Operating Process. Synthesis. 2013;45(18):2512-2519.A detailed study on the impact of the catalyst loading on conversion and enantioselectivity of the direct aldol reaction of an aldehyde and acetone in aqueous solvent with nonimmobilized and immobilized proline amide-based organocatalysts is described. Based on a polymer-supported catalyst, batch and semi-continuously operating processes, comprising recycling studies in the latter case, were investigated