The discovery of indazapyroxamet: a novel 3-pyridinyl insecticide targeting piercing/sucking insects.

In recent years, the registrations for a number of commercial insecticides utilized for piercing/sucking insects have been cancelled or restricted. To meet this growing need for new hemipteran controlling agrochemicals, we discovered a 2-(pyridin-3-yl)-thiazole compound, with limited insecticidal activity against cotton/melon aphid (Aphis gossypii). The 2-(pyridin-3-yl)-thiazole moiety offered us a basis to pursue the bicyclic 2-(pyridin-3-yl)-2H-indazole carboxamides.

Palladium-Catalyzed N-Arylation of Cyclopropylamines.

A general method has been developed for the previously challenging arylation of cyclopropylamine and N-arylcyclopropylamines. Highly active, air-stable, and commercially available R-allylpalladium precatalysts provide access to a wide range of (hetero)arylated cyclopropylanilines in high yields. Precatalysts [(tBuBrettPhos)Pd(allyl)]OTf and [(BrettPhos)Pd(crotyl)]OTf, deliver monoarylated products, while (PtBu3)Pd(crotyl)Cl is suited for preparing unsymmetrical diarylated products.

Rh-Catalyzed Intermolecular Reactions of α-Alkyl-α-Diazo Carbonyl Compounds with Selectivity over β-Hydride Migration.

Rh-carbenes derived from α-diazocarbonyl compounds have found broad utility across a remarkable range of reactivity, including cyclopropanation, cyclopropenation, C-H insertions, heteroatom-hydrogen insertions, and ylide forming reactions. However, in contrast to α-aryl or α-vinyl-α-diazocarbonyl compounds, the utility of α-alkyl-α-diazocarbonyl compounds had been moderated by the propensity of such compounds to undergo intramolecular β-hydride migration to give alkene products. Especially challenging had been intermolecular reactions involving α-alkyl-α-diazocarbonyl compounds.

Total Synthesis of Hyacinthacine A2: Stereocontrolled 5-aza-cyclooctene Photoisomerization and Transannular Hydroamination with Planar-to-Point Chirality Transfer.

The total synthesis of hyacinthacine A2 is reported via a novel transannular hydroamination in which planar chirality of a 5-aza-trans-cyclooctene precursor is transferred to point chirality in the product. Key to the success of this strategy was the development of a method for establishing absolute planar chirality via stereocontrolled photoisomerization of a 5-aza-cis-cyclooctene. This was accomplished by constructing a 5-aza-cis-cyclooctene precursor with a trans-fused acetonide.

Rh-catalyzed intermolecular reactions of cyclic α-diazocarbonyl compounds with selectivity over tertiary C-H bond migration.

Intermolecular Rh-catalyzed reactions of cyclic α-diazocarbonyl compounds with chemoselectivity over β-hydride elimination are described. These methods represent the first general intermolecular reactions of Rh-carbenoids that are selective over tertiary β-C-H bond migration. Successful transformations include cyclopropanation, cyclopropenation, and various X-H insertion reactions with a broad scope of substrates.

Rhodium(II)-catalyzed enantioselective C-H functionalization of indoles.

A catalytic, enantioselective method for the C-H functionalization of indoles by diazo compounds has been achieved. With catalytic amounts of Rh(2)(S-NTTL)(4), the putative Rh-carbene intermediates from α-alkyl-α-diazoesters react with indoles at C(3) to provide α-alkyl-α-indolylacetates in high yield and enantioselectivity. From DFT calculations, a mechanism is proposed that involves a Rh-ylide intermediate with oxocarbenium character.

The chiral crown conformation in paddlewheel complexes.

Bimetallic paddlewheel complexes derived from imides of (S)-tert-leucine adopt 'chiral crown' configurations in which the four imide groups are projected in a chiral arrangement on one face, and the four tert-butyl groups are projected on the opposite face. In this contribution, the generality of the chiral crown conformation is examined through crystallographic studies where the metal and the nature of the chiral ligands are altered. Based upon these observations, a model is proposed to explain the factors which create bias for the chiral crown configuration.

Chiral crown conformation of Rh(2)(S-PTTL)(4): enantioselective cyclopropanation with alpha-alkyl-alpha-diazoesters.

Herein, we provide crystallographic and computational evidence that Hashimoto's Rh(2)(S-PTTL)(4) catalyst adopts a "chiral crown" conformation with a reactive chiral face and an unreactive achiral face. In Rh(2)(S-PTTL)(4), all four tert-butyl groups are aligned on the same face of the catalyst, and each C-(t-Bu) bond is roughly parallel to the central Rh-Rh bond. This orients the four phthalimido groups on the opposite face of the catalyst.

Unusually reactive and selective carbonyl ylides for three-component cycloaddition reactions.

Conditions are described for the Rh-catalyzed formation of highly functionalized dihydro- and tetrahydrofuran products via three-component reactions of aldehydes, alpha-alkyl-alpha-diazoesters, and dipolarophiles. The alkyl-substituted carbonyl ylides that are generated in this fashion are highly reactive in cycloaddition reactions and display a scope of reactivity that is much broader than the three-component reactions of carbonyl ylides derived from ethyl diazoacetate or alpha-aryl-alpha-diazoesters. The reactions of alkyl-substituted carbonyl ylides proceed with high regioselectivity and diastereoselectivity that are rationalized in terms of an asynchronous, endo-selective transition state.

Rh-catalyzed intermolecular cyclopropanation with alpha-alkyl-alpha-diazoesters: catalyst-dependent chemo- and diastereoselectivity.

A Rh-catalyzed procedure for the cyclopropanation of alkenes with alpha-alkyl-alpha-diazoesters is described. With dirhodium tetraoctanoate, the predominant pathway is beta-hydride elimination. While a number of sterically demanding carboxylate ligands serve to avoid beta-hydride elimination, it was found that triphenylacetate (TPA) also imparts high diastereoselectivity.

Rh-catalyzed formation of dioxolanes from alpha-alkyl diazoesters: diastereoselective cycloadditions of carbonyl ylides with selectivity over beta-hydride elimination.

Described here is a diastereoselective Rh-catalyzed method for the preparation of dioxolanes from alpha-alkyl-alpha-diazoesters. This represents the first general method for generating carbonyl ylides from alpha-diazoesters that possess beta-hydrogens, as such diazo compounds typically give rise to alkenes via beta-hydride elimination. Subsequent cycloaddition with aromatic aldehydes gives tetrasubstituted dioxolanes with unusually high diastereoselectivity.

Development of a chipscale integrated microelectrode/microelectronic device for brain implantable neuroengineering applications.

An ultralow power analog CMOS chip and a silicon based microelectrode array have been fully integrated to a microminiaturized "neuroport" for brain implantable neuroengineering applications. The CMOS integrated circuit (IC) includes preamplifier and multiplexing circuitry, and a hybrid flip-chip bonding technique was developed to fabricate a functional, encapsulated microminiaturized neuroprobe device. Our neuroport has been evaluated using various methods, including pseudospike detection and local excitation measurement, and showed suitable characteristics for recording neural activities.