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.

Total synthesis and antileukemic evaluations of the phenazine 5,10-dioxide natural products iodinin, myxin and their derivatives.

A new efficient total synthesis of the phenazine 5,10-dioxide natural products iodinin and myxin and new compounds derived from them was achieved in few steps, a key-step being 1,6-dihydroxyphenazine di-N-oxidation. Analogues prepared from iodinin, including myxin and 2-ethoxy-2-oxoethoxy derivatives, had fully retained cytotoxic effect against human cancer cells (MOLM-13 leukemia) at atmospheric and low oxygen level. Moreover, iodinin was for the first time shown to be hypoxia selective. The structure-activity relationship for leukemia cell death induction revealed that the level of N-oxide functionality was essential for cytotoxicity. It also revealed that only one of the two phenolic functions is required for activity, allowing the other one to be modified without loss of potency.

On the cause of low thermal stability of ethyl halodiazoacetates.

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.

Microporous Molecular Materials from Dipeptides Containing Non-proteinogenic Residues.

Dipeptides with two hydrophobic side chains have proved to be an exceptional source of microporous organic materials, but since previous structures were limited to the incorporation of only proteinogenic residues, their full potential as adsorbents has remained unexplored. Single-crystal XRD data for ten new compounds with non-proteinogenic L-2-aminobutanoic acid and/or L-2-amino-pentanoic acid are presented. The gas-phase accessibility of their crystal pores, with cross-sections of 2.3 to 5.1 Å, was monitored by CO2 and CH4 adsorption isotherms. Included CO2 was also detected spectroscopically by 2D MAS NMR. An extensive conformational analysis reveals that the use of linear rather than branched side chains (such as L-valine and L-isoleucine) affords peptides with a greater degree of conformational freedom and yields more-flexible channel surfaces that may easily adapt to a series of potential guest molecules.

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.

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 1A, 2A, and 3A, 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(-).

A solid-state oxidation of 1,1,3,3-tetramethylguanidinium 4-methylbenzenesulfinate to 1,1,3,3-tetramethylguanidinium 4-methylbenzenesulfonate.

The organic acid-base complex 1,1,3,3-tetramethylguanidinium 4-methylbenzenesulfonate, C5H14N3(+)·C7H7O3S(-), was obtained from the corresponding 1,1,3,3-tetramethylguanidinium 4-methylbenzenesulfinate complex, C5H14N3(+)·C7H7O2S(-), by solid-state oxidation in air. Comparison of the two crystal structures reveals similar packing arrangements in the monoclinic space group P2(1)/c, with centrosymmetric 2:2 tetramers being connected by four strong N-H···O=S hydrogen bonds between the imine N atoms of two 1,1,3,3-tetramethylguanidinium bases and the O atoms of two acid molecules.

1,4-Bis(2-diazo-acet-yl)piperazine.

The asymmetric unit of the title compound, C8H10N6O2, contains one-half mol-ecule, which is completed by a crystallographic center of symmetry. The piperazine ring adopts a chair conformation. In the crystal, weak C-H⋯O inter-actions link the mol-ecules into layers parallel to the bc plane. The crystal packing also exhibits short N⋯N contacts of 3.0467 (16) Šbetween the terminal diazo N atoms from neighbouring mol-ecules.

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-ß-lactams. When carried out with α-bromodiazoacetamides bearing cyclic side chains, the thermolysis reaction affords bicyclic α-halo-ß-lactams, in some cases in excellent yields, depending on the ring size and substitution pattern of the cyclic amide side chains.