Ruthenium(II)-Catalyzed Asymmetric Transfer Hydrogenation of Ketones Using a Formic Acid−Triethylamine Mixture

▪ Abstract Studies of dispersal polymorphism in insects have played a pivotal role in advancing our understanding of population dynamics, life history evolution, and the physiological basis of adaptation. Comparative data on wing-dimorphic insects provide the most definitive evidence to date that habitat persistence selects for reduced dispersal capability. The increased fecundity of flightless females documents that a fitness trade-off exists between flight capability and reproduction. However, only recently have studies of nutrient consumption and allocation provided unequivocal evidence that this fitness trade-off results from a trade-off of internal resources. Recent studies involving wing-dimorphic insects document that flight capability imposes reproductive penalties in males as well as females. Direct information on hormone titers and their regulation implicates juvenile hormone and ecdysone in the control of wing-morph determination. However, detailed information is available for only one species,...

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Physiology and ecology of dispersal polymorphism in insects

Cytochromes P450 and insecticide resistance.

4.1 – Insect Cytochrome P450

Metal-organic frameworks (MOFs) are finding increasing application as solid catalysts for liquid phase reactions leading to the synthesis of fine chemicals. In the present review we have focused on those reports describing the use of MOFs as catalysts for the synthesis of N-containing heterocycles that is a class of organic compounds with high added value due to their therapeutic use as drugs and their remarkable biological activities. After an introduction describing relevant structural features of MOFs and the nature of their active sites, this manuscript is organized according to the type of N-containing heterocycle synthesized employing MOFs as catalysts including pyrimidines, N-substituted piperidines, quinolines, indoles, N-substituted imidazoles, triazoles and heterocyclic amides. Special attention has been paid to the structural stability of MOFs under the reaction conditions, to the occurrence of metal leaching and reusability. The final section of this review provides some concluding remarks and future prospects for the field, with emphasis on showing the superiority of MOFs with respect to other solid catalysts for this type of liquid phase organic reactions and pointing out that the final goal in this research would be the use of these materials as catalysts in real industrial synthesis.

Metal–organic frameworks as solid catalysts for the synthesis of nitrogen-containing heterocycles

5-(Arylmethylene)hydantoins (4-19) and 5-(arylmethylene)-2-thiohydantoins (20-37) have been synthesized by condensation of aromatic aldehydes with hydantoin (1) or 2-thiohydantoin (2) in the presence of ethanolamine. A number of 5-alkyl- and 5-(arylmethyl)hydantoins (40-48) and their 2-thio analogs (50-55) were synthesized from amino acids. All of these compounds were tested for pesticidal activity.

Preparation and fungicidal activity of 5-substituted hydantoins and their 2-thio analogs

A novel synthesis of precocenes. Efficient synthesis and regioselective O-alkylation of dihydroxy-2,2-dimethyl-4-chromanones

The cytochrome P-450-dependent microsomal and mitochondrial ecdysone 20-monooxygenase systems convert ecdysone into 20-hydroxyecdysone. The microsomal fraction of fat bodies of zero h wandering stage fleshfly larvae (Neobellieria bullata; Diptera: Sarcophagidae) has a high ecdysone 20- monooxygenase activity. The effects of cytochrome P-450 inhibitors were investigated in vitro on microsomal ecdysone 20-monooxygenase. Metyrapone, fenarimol and certain imidazole derivatives (KK-42, KK-110, KK-135 and PIM) are strong inhibitors. The IC50 value of KK-110, which is the strongest inhibitor, is 2 × 10−7 M. A triazolyl and two cyclopropylamine derivatives have low activity. The activities of different NADPH-cytochrome c (P-450) reductase inhibitors were also assessed; diquat dibromide is a moderate inhibitor of microsomal ecdysone 20-monooxygenase, while paraquat dichloride has no activity.



In-vivo experiments with cytochrome P-450 inducers and inhibitors gave the following results: (a) fenarimol, FI-121, precocene-2 caused “permanent” first-instar larvae; (b) barbital, phenobarbital and their sodium salts caused significant delay in larval development; (c) PIM, PTM, metyrapone, KK-42, KK-135, J-2710, RH 5849 and colchicine caused moulting disturbances; (d) J-2710, PIM, PTM, KK-42, KK-135, RH 5849 and colchicine caused lethal spiracle and mandible malformation; (e) KK-110, fenarimol, barbital and phenobarbital caused precocious pupariation.

Cytochrome P-450 Inducers and Inhibitors Interfering with Ecdysone 20-Monooxygenases and Their Activities during Postembryonic Development of Neobellieria bullata Parker

The precocenes have notable effects on insect development, in particular they can induce specific destruction of corpora allatal cells and thus prevent the synthesis of juvenile hormones. As juvenile hormones have wide-ranging physiological roles in insects, from metamorphosis to reproduction, the effects of precocenes are also diverse. It has been suggested that high juvenile hormone titres in aphids induce the development of wingless adult forms while low titres promote the development of winged forms. The morphogenetic effects of precocene derivatives on aphids are complex. They can affect wing dimorphism in some species, both promoting wing development and inhibiting wing development, depending upon experimental strategy, and can exhibit the classical induction of precocious adult development indicating destruction of the corpus allatum. The morphogenetic effects promoted by a series of precocenes and 2,2-dimethylchromene derivatives have been investigated in the pea aphid, Acyrthosiphon pisum (Harris), and structure-activity relations determined for wing induction, wing inhibition, and precocious metamorphosis. These experiments show that compounds which promote wing development are not, or not so, effective in wing inhibition and that the compounds that inhibit wing formation are more closely aligned with those that induce precocious metamorphosis. Substitution of alkylthio for alkoxy groups at C7 alters the morphogenetic activity profile while 2,2-dimethylchroman derivatives have no morphogenetic activity. © 1996 Wiley-Liss, Inc.

Precocene derivatives and aphid morphogenesis

The synthesis of novel benzopyran compounds analogues of the natural precocenes is described. These derivatives are obtained via novel synthesis and regioselective O-alkylation of 6-chloro- and 6-tert-butyl-7,8-dihydroxy-2,2-dimethyl-4-chromanones

Selective syntheses of analogues of the natural precocenes: synthesis and regioselective O-alkylation of 6-chloro- and 6-tert-butyl-7,8-dihydroxy-2,2-dimethyl-4-chromanones

Tibor Timar

Papers

Preparation and fungicidal activity of 5-substituted hydantoins and their 2-thio analogs

A novel synthesis of precocenes. Efficient synthesis and regioselective O-alkylation of dihydroxy-2,2-dimethyl-4-chromanones

Cytochrome P-450 Inducers and Inhibitors Interfering with Ecdysone 20-Monooxygenases and Their Activities during Postembryonic Development of Neobellieria bullata Parker

Precocene derivatives and aphid morphogenesis

Selective syntheses of analogues of the natural precocenes: synthesis and regioselective O-alkylation of 6-chloro- and 6-tert-butyl-7,8-dihydroxy-2,2-dimethyl-4-chromanones