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A flexible and efficient synthesis of the potent human topoisomerase inhibitor (5 Z,9 Z)-eicosa-5,9-dienoic acid was explored; the presented method represents a generally applicable approach towards demospongic acids and related natural products. Key steps of the synthesis involve chemoselective hydroboration, Corey-Fuchs alkynylation, Z-selective Lindlar reduction, tetrapropylammonium perruthenate catalyzed direct oxidation of a primary alcohol to the corresponding acid, and Arndt-Eistert homologation. Thus, the total synthesis of (5 Z,9 Z)-eicosa-5,9-dienoic acid was achieved in 10 steps in an overall yield of 20 %. [ABSTRACT FROM AUTHOR]

( tert-Butyl- NNO-azoxy)acetonitrile ( 1) is a useful precursor for a number of nitrogen heterocycles. It was found that it could be obtained in good yield by treatment of the salts of ( tert-butyl- NNO-azoxy)(hydroxyimino)acetonitrile with NH2OTs. It is the first case of one-step reduction of an oxime group to a methylene unit using an aminating agent. A plausible reaction mechanism is proposed. In addition, a new strategy for the tetrazole 1-oxide ring construction was developed. This involves a diazo-group transfer to the active-methylene unit of compound 1, followed by intramolecular coupling of the azoxy and diazo groups. The tetrazole structures were confirmed by X-ray diffraction analysis. [ABSTRACT FROM AUTHOR]

Benzopyrazinoisoindigo, a pigment reported 40 years ago, should be a good candidate for n-type semiconductors if the reported structure is correct. Reinvestigation of this molecule revealed that it is actually (4 H,4′ H)-benzopyrazinoisoindigo, which could be considered as the reduced form of benzopyrazinoisoindigo, and hence, it is a good candidate for p-type semiconductors. The route toward the synthesis of this molecule was optimized, and a mechanism was accordingly proposed. A field-effect transistor based on this material showed a hole mobility up to 2.5 × 10-2 cm2 V-1 s-1. [ABSTRACT FROM AUTHOR]

Aliskiren is the first-in-class orally active direct renin inhibitor. It was approved in 2007 for the treatment of hypertension. We have designed a new strategy for the convergent synthesis of aliskiren that involves a catalytic stereoselective nitroaldol reaction as the key step. A new enantiopure nitroalkane (synthon A1), prepared in only three steps from a commercially available enantiopure 2-(arylmethyl)-3-methyl butanol derivative, was successfully used in a copper-catalysed Henry reaction to give a nitrolactone intermediate in which the correct configuration for the final product was established at all four stereocentres. Nitro-group reduction, Boc-protection of the resulting amine, aminolysis of the lactone with 3-amino-2,2-dimethylpropionamide, and finally Boc-deprotection led to the enantiopure renin inhibitor aliskiren. [ABSTRACT FROM AUTHOR]

The amine-bis(phenolate) iron(III)-catalysed reduction of ketones and aldehydes to the corresponding secondary and primary alcohols by a consecutive hydrosilylation/hydrolysis process is reported. The amine-bis(phenolate) iron(III) catalyst is easily accessible, stable towards moisture and air and has a broad substrate scope. [ABSTRACT FROM AUTHOR]

The partial reduction of α,β-unsaturated esters and benzoate derivatives to form the corresponding aldehydes was achieved using a flow reactor system within 1 s at a high flow rate (18 mL min-1) under cryogenic conditions (-97 °C). Commercially available diisobutylaluminium hydride (DIBAL-H) was used as the reductant. The desired enals and benzaldehyde derivatives, except for 4-methoxycinnamate and 4-methoxybenzoate, were formed selectively and redox economically in moderate to high yields. [ABSTRACT FROM AUTHOR]