A rapid ultrasound-promoted Horner–Wadsworth–Emmons reaction for the preparation of ferrocene derivatives. Application to ferrocene-modified ITO electrodes

The Horner–Wadsworth–Emmons reaction of ferrocenecarboxaldehyde with various phosphonate-stabilized carbanions has been performed under ultrasound irradiation. The reaction time at ambient temperature was considerably shortened (5–15 min) compared to nonsonicated conditions requiring often refluxing for 6–24 h. Control of the reaction time can be achieved by tuning the base strength in different solvents. This method was successfully applied to the preparation of various 2-substituted vinylferrocenes. The as-prepared (E)-2-ferrocenylvinylphosphonic acid was used to modify ITO electrodes to form redox-active functionalized ITO electrodes which have been characterized by means of electrochemical techniques.     

Recent topics of the natural product synthesis by Horner–Wadsworth–Emmons reaction

The Horner–Wadsworth–Emmons (HWE) reaction has become well established among existing methodologies for the highly stereoselective olefination of carbonyl compounds. The reliability of this reaction in terms of its robustness, high stereoselectivity, and broad substrate scope permit retrosynthetic disconnection of the olefin bond in α,β-unsaturated carbonyl intermediates in natural product synthesis. This review discusses recent applications of the HWE reaction in natural product synthesis, highlighting its use for carbon chain elongation, coupling reactions of synthetic segments, ring-closing reactions, tandem reactions including HWE olefination, and asymmetric reactions.     

Synthesis of 6E－Geranylgeraniol－19－oic Acid

The present paper deals with the facile synthesis of 6E-geranylgeraniol-19-oic acid(l), a naturally occuring alicyclic diterpene acid, by a Horner-Wadsworth-Emmons olefination of two readily available fragments 7 and 3.     

Interlaboratory quality audit program for potable water – assessment of method validation done on inductively coupled plasma atomic emission spectrometer (ICP-AES)

In an effort to assess the method validation done using ICP-AES in our laboratory for potable water, an Environmental Laboratory Approval Program organized by New York State Department of Health, Wadsworth Center providing the reference material has been undertaken for 14 trace elements and seven other chemical constituents. The certified means for the reference material and the results obtained in our laboratory are compared. The comparisons helped us assess the quality of our work. All the data from the inductively coupled plasma atomic emission spectrometer (ICP-AES) fall into the ranges specified. These data are intended to depict the quality of chemical analysis being conducted in our laboratory and to increase the level of confidence of our clientele in accepting our test reports. It should be further noted that while the technique may not be new, the model is new and the simultaneous detection of elements required validation for those of our clientele who are only familiar with sequential AAS and AES. Received: 3 April 2002 Accepted: 4 September 2002     

trans-Tetradec-2-enoic Acid in Impatiens glandulifera

Purification of the hydrophobic extracts of the flowers and seed pods of Impatiens glandulifera(Himilayan balsam) yielded 2-methoxy-[1,4]-naphthoquinone 1, 1-hydroxyeicosan-3-one 16, and an unusual unsaturated fatty acid, trans-tetradec-2-enoic acid 6. Mass spectrometry and nuclear magnetic resonance spectroscopy indicated that the latter compound (6) was isolated as a mixture with linolenic acid 8 and saturated acids 7, 9, and 10 (chain lengths C-16, 18, and 20). Its structure was subsequently proven by independent chemical synthesis.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.     

Enantioselective total synthesis of (+)-sarcandralactone A

An enantioselective total synthesis of the lindenane sesquiterpene (+)-sarcandralactone A has been accomplished for the first time. The synthesis features a SeO₂-mediated [2,3]-sigmatropic rearrangement for the facile construction of the tertiary allylic alcohol as a single diastereoisomer.