A new phenylethyl alkyl amide from the Ambrostoma quadriimpressum Motschulsky

• Guolei Zhao,
• Chao Yang,
• Bing Li and
• Wujiong Xia

Beilstein J. Org. Chem. 2011, 7, 1342–1346, doi:10.3762/bjoc.7.158

• according to the synthetic plan shown in Scheme 5. Oxidation of the alcohol 12 with PCC afforded the corresponding aldehyde 16, followed by a Wittig reaction with salt 15 in the presence of two equiv LDA, which afforded the adduct 17 as an (E/Z)-mixture in 72% yield. The E/Z isomers of 17 were not separated

Toward an integrated route to the vernonia allenes and related sesquiterpenoids

• Da Xu,
• Michael A. Drahl and
• Lawrence J. Williams

Beilstein J. Org. Chem. 2011, 7, 937–943, doi:10.3762/bjoc.7.104

• the direct formation of 21 via bromomethyltriphenylphosphonium bromide (Scheme 4). This reaction was inefficient and gave both the (E)- and (Z)-bromoolefins as well as dibromoolefin 20. Bromo group scrambling under basic Wittig reaction conditions is known [63], and the usual procedure for Wittig

Construction of cyclic enones via gold-catalyzed oxygen transfer reactions

• Leping Liu,
• Bo Xu and
• Gerald B. Hammond

Beilstein J. Org. Chem. 2011, 7, 606–614, doi:10.3762/bjoc.7.71

• oxygen transfer from a carbonyl group to a carbon–carbon triple bond, the so-called alkyne–carbonyl metathesis. This methodology has sparked the attention of the synthetic community, because it could serve as an efficient and atom-economic alternative to the Wittig reaction by the formation of a new

Application of the diastereoselective photodeconjugation of α,β-unsaturated esters to the synthesis of gymnastatin H

• Ludovic Raffier and
• Olivier Piva

Beilstein J. Org. Chem. 2011, 7, 151–155, doi:10.3762/bjoc.7.21

• configuration of the C-6 centre of the target molecule was controlled. Keywords: amide; diastereoselective protonation; dienol; isomerisation; Wittig reaction; Introduction The photodeconjugation of α,β-unsaturated esters 1 – which bear at least one hydrogen atom on γ-position – allows a straightforward

Enantioselective synthesis of tricyclic amino acid derivatives based on a rigid 4-azatricyclo[5.2.1.0^2,6]decane skeleton

• Matthias Breuning,
• Tobias Häuser,
• Christian Mehler,
• Christian Däschlein,
• Carsten Strohmann,
• Andreas Oechsner and
• Holger Braunschweig

Beilstein J. Org. Chem. 2009, 5, No. 81, doi:10.3762/bjoc.5.81

• oxidation of the alkene rac-13 (Scheme 3), which was available from the ketone rac-9 either by Wittig reaction or by a Tebbe-type olefination [31] using Mg, TiCl4, and CH2Cl2. Hydroboration/oxidation of rac-13 occurred highly diastereoselectively on the exo-side providing the desired endo-alcohol rac-14, as

• , and thus proximity-facilitated tandem hydride transfer/cyclization sequence [33]. Since the yields of rac-15 from the alkene rac-13 were low, we turned our attention to an alternative approach via the enol ether 18, which was available from 9 as a 1:1 mixture of E/Z-isomers by Wittig reaction with

Ring strain and total syntheses of modified macrocycles of the isoplagiochin type

• Andreas Speicher,
• Timo Backes,
• Kerstin Hesidens and
• Jürgen Kolz

Beilstein J. Org. Chem. 2009, 5, No. 71, doi:10.3762/bjoc.5.71

• boronic acid 22 with the bromoarene 16 under carefully optimized conditions followed by acidic workup afforded the hydroxyaldehyde 27 as precursor for cyclization (Scheme 6). A cyclization protocol for the intramolecular Wittig reaction, well established [15][20] for the synthesis of the tetramethyl ether

Green oxidations: Titanium dioxide induced tandem oxidation coupling reactions

• Vineet Jeena and
• Ross S. Robinson

Beilstein J. Org. Chem. 2009, 5, No. 24, doi:10.3762/bjoc.5.24

• to extend the methodology, a preliminary investigation into a titanium dioxide mediated tandem Wittig reaction was attempted in which the intermediate aldehyde is trapped by a stabilised phosphorane. Unfortunately, NMR spectroscopic analysis revealed a multitude of peaks, none of which were

An expedient synthesis of 5-n-alkylresorcinols and novel 5-n-alkylresorcinol haptens

• Kirsti Parikka and
• Kristiina Wähälä

Beilstein J. Org. Chem. 2009, 5, No. 22, doi:10.3762/bjoc.5.22

• Helsinki, Finland 10.3762/bjoc.5.22 Abstract The first synthesis of bioactive long alkyl chain 5-n-alkylresorcinols, present in whole grain products, by a novel modification of the Wittig reaction is described. All the main long chain 5-n-alkylresorcinols present in rye and wheat, including C23 and C25

• way for the immunochemical detection techniques of alkylresorcinols. Keywords: 5-n-alkylresorcinols; haptens; microwave assisted synthesis; Wittig reaction; Introduction 5-Alk(en)ylresorcinols and related compounds are phenolic lipids present in several families of plants (e.g. Gramineae

• reduced AR, the lack of stereochemical control was of no consequence. Following the Wittig reaction, catalytic hydrogenation and demethylation gave AR and AR haptens in ca. 40% overall yield. The Wittig product 7b was a practical starting material for the C23 hapten (2d), for which commercial alkanal or

Reversible intramolecular photocycloaddition of a bis(9-anthrylbutadienyl)paracyclophane – an inverse photochromic system. (Photoactive cyclophanes 5)

• Henning Hopf,
• Christian Beck,
• Jean-Pierre Desvergne,
• Henri Bouas-Laurent,
• Peter G. Jones and
• Ludger Ernst

Beilstein J. Org. Chem. 2009, 5, No. 20, doi:10.3762/bjoc.5.20

• structure and photochromic properties of 2 are reported in this paper. Results and Discussion 1 Synthesis Compound 2 was prepared from dialdehyde 3 using the Wittig reaction, as outlined in Scheme 1, in 48% yield. Dialdehyde 3 wasobtained in five steps from [2.2]paracylophane, a commercial product, in 72

• % overall yield as described previously [19]. Therefore, the overall yield of 2 from the parent cyclophane was found tobe 35% on the gram scale. The Wittig reaction provides a mixture of cis and trans isomers, but the pure all-trans isomer was isolated by crystallization as orange crystals (see Experimental

• structure of 4 (1,4 : 2′,3′-cycloadduct). Preparation of 2 (last step), using the Wittig reaction. The preparation of 3 has been described in ref [19]. Angles between various partial planes in molecule 2 in the crystal. Supporting Information Supporting Information File 40: Thermal dissociation of

Convenient methods for preparing π-conjugated linkers as building blocks for modular chemistry

• Jiří Kulhánek,
• Filip Bureš and
• Miroslav Ludwig

Beilstein J. Org. Chem. 2009, 5, No. 11, doi:10.3762/bjoc.5.11

• and 4-bromobenzyl(triphenyl)phosphonium bromide [37] by the Wittig reaction [37][38] in 37 and 54% yields, respectively. In contrast to the Horner–Wadsworth–Emmons reaction, this procedure afforded both (E)- and (Z)-stilbenes that were isomerized by heating with traces of iodine in toluene to afford

Catalytic synthesis of (E)-α,β-unsaturated esters from aldehydes and 1,1-diethoxyethylene

• Rubén Manzano,
• Lidia Ozores,
• Andreas Job,
• Lars Rodefeld and
• Benjamin List

Beilstein J. Org. Chem. 2009, 5, No. 3, doi:10.3762/bjoc.5.3

• high yielding synthesis of α,β-unsaturated esters from aldehydes and 1,1-diethoxyethylene was developed. Keywords: 1,1-diethoxyethylene; α,β-unsaturated esters; Introduction A number of reactions transforming aldehydes into α,β-unsaturated esters have been developed and especially Wittig reaction

A facile synthesis and fungicidal activities of 2-(alkylamino)-5,6-dimethylthieno[2,3-d]pyrimidin- 4(3H)-ones

• Yang-Gen Hu,
• Ai-Hua Zheng,
• Xu-Zhi Ruan and
• Ming-Wu Ding

Beilstein J. Org. Chem. 2008, 4, No. 49, doi:10.3762/bjoc.4.49

• activities against six kinds of fungi. Keywords: 2-(alkylamino)-5,6-dimethylthieno[2,3-d]pyrimidin-4(3H)-one; aza-Wittig reaction; fungicidal activity; synthesis; Introduction Over the past ten years, aza-Wittig reactions of functionalized iminophosphoranes with isocyanates have been applied to produce

• interested in the synthesis of a series of new heterocyclic compounds via aza-Wittig reaction of α- or β-(ethoxycarbonyl)-substituted iminophosphoranes with aromatic isocyanates and subsequent reaction with various nucleophiles under mild conditions [11][12][13][14]. Herein we wish to report an efficient

Recent progress on the total synthesis of acetogenins from Annonaceae

• Nianguang Li,
• Zhihao Shi,
• Yuping Tang,
• Jianwei Chen and
• Xiang Li

Beilstein J. Org. Chem. 2008, 4, No. 48, doi:10.3762/bjoc.4.48

• utilizing Wu’s own methodology. Wittig reaction of the aldehyde 37 and the Wittig reagent 38 furnished the butenolide unit 39. The tetrahydrofuran part of 22 was constructed from D-glucose via epoxide 40. The entire carbon skeleton of 41 was constructed by Pd(0)-catalyzed cross-coupling reaction between 39

• building block 45 by means of the Sharpless AD reaction and cyclization catalyzed by Co(modp)2 (the Mukaiyama epoxidation method) under mild reaction conditions. The connection of the THF unit 46 with the γ-lactone segment 47 was carried out by means of a Wittig reaction. The target compound 42 had

• conditions resulted in a smooth conversion of the starting material into THF 89. Triol (+)-90 was obtained with lipase Amano AK desymmetrization. For the appropriate side chain attachment, the termini were differentiated to give lactone (−)-91. Reduction of (−)-91 followed by a Wittig reaction yielded fully

End game strategies towards the total synthesis of vibsanin E, 3-hydroxyvibsanin E, furanovibsanin A, and 3-O-methylfuranovibsanin A

• Brett D. Schwartz,
• Craig M. Williams and
• Paul V. Bernhardt

Beilstein J. Org. Chem. 2008, 4, No. 34, doi:10.3762/bjoc.4.34

• lithium aluminium hydride proceded smoothly, however, global oxidation caused significant problems yielding only very low amounts of aldehyde 52, which was not enough to attempt the Wittig reaction with 45 (Scheme 8). In the view of the diasppointing results obtained above (Scheme 8) all attention was

Flexible synthesis of poison- frog alkaloids of the 5,8-disubstituted indolizidine- class. II: Synthesis of (-)-209B, (-)-231C, (-)-233D, (-)-235B", (-)-221I, and an epimer of 193E and pharmacological effects at neuronal nicotinic acetylcholine receptors

• Soushi Kobayashi,
• Naoki Toyooka,
• Dejun Zhou,
• Hiroshi Tsuneki,
• Tsutomu Wada,
• Toshiyasu Sasaoka,
• Hideki Sakai,
• Hideo Nemoto,
• H. Martin Garraffo,
• Thomas F. Spande and
• John W. Daly

Beilstein J. Org. Chem. 2007, 3, No. 30, doi:10.1186/1860-5397-3-30

• (-)-231C, (-)-221I and (-)-epi-193E on α4β2 and α7 nicotinic receptors, the most abundant subtypes in the mammalian brain. [4] Results and Discussion Reduction of the lactam 1 [1] with LiAlH4 followed by Swern oxidation of the resulting alcohol and Wittig reaction gave the olefin 3 in 78% overall yield

• (Scheme 1). Hydrogenation of the double bond in 3 with 10% Pd/C provided (-)-209B, whose spectral data were identical with reported values. [7] The lactam 1 was also converted to the alcohol 4, [1] which was transformed into (-)-235B" by Swern oxidation followed by Wittig reaction under high dilution and

• 'salt free' conditions (Scheme 1). The spectral data of synthetic (-)-235B" were identical with reported values. [8][9] Indolizidines (-)-231C [10] and (-)-233D [10] were synthesized from common intermediate 5 prepared from the alcohol 4. Thus, the Swern oxidation of 4 and then the Wittig reaction of

Flexible synthetic routes to poison- frog alkaloids of the 5,8-disubstituted indolizidine- class I: synthesis of common lactam chiral building blocks and application to the synthesis of (-)-203A, (-)-205A, and (-)-219F

• Naoki Toyooka,
• Dejun Zhou,
• Hideo Nemoto,
• H. Martin Garraffo,
• Thomas F. Spande and
• John W. Daly

Beilstein J. Org. Chem. 2007, 3, No. 29, doi:10.1186/1860-5397-3-29

• , CHCl3)) suggest that the absolute stereochemistry of natural 203A is 5S, 8R, 9S. We achieved the total synthesis of (-)-205A starting from 1 via 13 (Scheme 3). Lithium aluminum hydride reduction of 13 followed by Swern oxidation and Wittig reaction of the resulting aldehyde gave the olefin 17

• , followed by an Arndt-Eistert sequence of the resulting carboxylic acid. Reduction of both carbonyl groups in 14 with lithium aluminum hydride provided the alcohol, which was directly used for formation of Z-iodoolefin 15. Thus, the Dess-Martin periodinane oxidation [24] of the alcohol, followed by Wittig

• reaction of the resulting aldehyde under Stork's reaction conditions, [25] gave the olefin. Purification by silica gel column chromatography afforded pure 15 in 60% isolated yield. The coupling reaction of 15 with TMS-acetylene under Sonogashira's conditions [26] gave rise to the product 16. Finally