An efficient one-pot four-step domino reaction of substituted β-ketoesters has been optimized giving rise to a large panel of C2-substituted 3-methylcyclohex-2-enones, an important scaffold for the preparation of various initiators for cationic or radical cyclizations. The developed methodology is quite general and applicable to a wide range of β-ketoester substrates, allowing the introduction of various functionalities at the C2 position of the 3-methylcyclohex-2-enones, in good to excellent yields.

http://dx.doi.org/10.1016/j.tet.2010.07.029

Helicobacter pylori, a gastric pathogen, binds to various blood group antigens, including the Lewis types, present in the gastric tissue and a relation between the presentation of the ligands and the overall strength of binding has been assumed. Synthetic Lewis b tetra- and hexasaccharide conjugates are available but not the analogous pentasaccharide. An efficient synthesis of the amino spacer equipped Lewis b pentasaccharide, 3-aminopropyl α-l-fucopyranosyl-(1→2)-β-d-galactopyranosyl-(1→3)-[α-l-fucopyranosyl-(1→4)]-2-acetamido-2-deoxy-β-d-glucopyranosyl-(1→3)-β-d-galactopyranoside, is presented to enable further investigation of the carbohydrate recognition process of H. pylori.

http://dx.doi.org/10.1016/j.tet.2010.07.036

We report a novel approach to the synthesis of GlcNAcstatins—members of an emerging family of potent and selective inhibitors of peptidyl O-GlcNAc hydrolase build upon tetrahydroimidazo[1,2-a]pyridine scaffold. Making use of a streamlined synthetic sequence featuring de novo synthesis of imidazoles from glyoxal, ammonia and aldehydes, a properly functionalised linear GlcNAcstatin precursor has been efficiently prepared starting from methyl 3,4-O-(2′,3′-dimethoxybutane-2′,3′-diyl)-α-d-mannopyranoside. Subsequent ring closure of the linear precursor in an intramolecular S_N2 process furnished the key fused d-mannose-imidazole GlcNAcstatin precursor in excellent yield. Finally, a sequence of transformations of this key intermediate granted expeditious access to a variety of the target compounds bearing a C(2)-phenethyl group and a range of N(8) acyl substituents. The versatility of the new approach stems from an appropriate choice of a set of acid labile permanent protecting groups on the monosaccharide starting material. Application was demonstrated by the synthesis of GlcNAcstatins containing polyunsaturated and thiol-containing amido substituents.

http://dx.doi.org/10.1016/j.tet.2010.07.037

The synthesis of three azasugar-containing analogs of the disaccharide units of heparan sulfate, which are potential inhibitors of the enzyme heparanase, is reported. Synthetic routes were developed for the preparation of l-ido-nojirimycin type glycosyl acceptors with O-4 free. Glycosylation of these acceptors with an O-6 functionalized 2-azido-2-deoxy-d-glucose thioglycoside donor afforded the α-linked disaccharides in good yields. The advantages of using the 4-nitrobenzenesulfonyl group for the protection of the ring nitrogen of azasugars were demonstrated.

http://dx.doi.org/10.1016/j.tet.2010.07.055

A novel β-cyclodextrin (β-CD) derivative containing mono-phenylamino (MPA-β-CD) was newly synthesized by classical Mitsunobu reaction in good yield, and its structure has been confirmed by ¹H NMR, ¹³C NMR and electrospray ionization mass spectra. The compound MPA-β-CD was immobilized onto glassy carbon electrode (GCE) by diazotization, and with this modified electrode the binding behavior of MPA-β-CD for ferrocene (Fc) was investigated qualitatively, and the comparison of differential pulse voltammetry before and after immersion in ferrocene solution indicated that the MPA-β-CD immobilized GCE exhibited the molecular recognition behavior between β-CD and ferrocene.

http://dx.doi.org/10.1016/j.tet.2010.07.052

Three unusual natural products, viz., alstopirocine, a macroline alkaloid incorporating a substituted pyrrole moiety, pleiomaltinine, an alkaloid–pyrone adduct, and pleiomalicine, an alkaloid–carbamic acid adduct, were isolated from the Malayan Alstonia angustifolia. The alkaloid moiety in alstopirocine was alstomicine while that in pleiomaltinine and pleiomalicine was pleiocarpamine. The structures were determined by spectroscopic methods and in the case of pleiomaltinine, confirmed by X-ray diffraction analysis. Possible biogenetic pathways to these unusual compounds are presented.

http://dx.doi.org/10.1016/j.tet.2010.07.079

The Diels–Alder reaction between C₆₀ and anthryl glycodendron, which has d- or l-gluconamides at the terminals, gave a new fullerene glycodendron conjugate. Interestingly, the diastereoselective cycloaddition reaction proceeded upon the treatment of C₆₀ with the anthryl dendron 3. Furthermore, optical pure fullerodendrons (−)-4L and (+)-4D, which were confirmed by ¹H and ¹³C NMR spectroscopy, FT-IR, MALDI-TOF mass spectroscopic analysis, were isolated from the mixture of diastereomers. And their absolute configurations were predicted by the use of CD spectra.

http://dx.doi.org/10.1016/j.tet.2010.07.061

DABCO-mediated Morita–Baylis–Hillman reactions of several 1-substituted-indole-2-carboxaldehydes are disclosed. It was discovered that carboethoxy or tert-butoxycarbonyl groups installed at N-1 undergo cleavage under the reaction conditions to afford 2-substituted indoles. Utility of the N-substituted adducts for preparing a variety of annulated indoles has been exemplified.

http://dx.doi.org/10.1016/j.tet.2010.07.078

This paper describes the use of (−)-sclareol in the synthesis of the tricyclic diterpenes of abietane skeleton, such as (+)-ferruginol and (+)-sugiol, using as key step the lateral lithiation of a dinorditerpene derivative.

http://dx.doi.org/10.1016/j.tet.2010.07.066

A simple and convenient one-pot multicomponent reaction (MCR) has been developed for the synthesis of highly functionalized piperidines catalyzed by molecular iodine. This strategy demonstrated five-component reactions of 1,3-dicarbonyl compounds, amines and aromatic aldehydes in methanol using 10 mol % of iodine at room temperature. This methodology provides an alternative approach for easy access of highly and fully substituted piperidines in moderate to good yields using three readily available starting materials. Notably, this method is mild, cheap, straight forward, applicable to broad range of substrates and environmentally friendly as compared to the existing methods. Synthetic and mechanistic studies are presented here.

http://dx.doi.org/10.1016/j.tet.2010.07.075

A new, efficient, and inexpensive CuCl₂/salicylic acid catalytic system has been developed to catalyze Sonogashira-type cross-coupling of haloarenes and iodoheteroarenes with terminal alkynes under mild reaction conditions to afford the corresponding coupling products in 18–95% yields. The role of salicylic acid might act as a bidentate O,O-donor ligand to activate the catalytic reactivity of copper chloride in coupling reactions was also briefly discussed.

http://dx.doi.org/10.1016/j.tet.2010.07.072

1,1,3,3,6-Pentamethyl-1,3-disilaindan-5-ol (2) is a key intermediate in the synthesis of new sila-substituted gonadotropin releasing hormone receptor antagonists, such as 1. In order to produce sufficient quantities of 1 for pharmacological and toxicological evaluation, an efficient synthesis of 2 has been developed. (1,1,3,3,6-Pentamethyl-1,3-disilaindan-5-yl)methanal (11) was synthesized in a one-pot procedure. CoBr₂/Zn-catalyzed [2+2+2] cycloaddition of diyne 3 with the commercially available monoalkyne 15 was achieved through a slow addition of 3 and CoBr₂ to a mixture of 15 and zinc powder in refluxing acetonitrile, giving rise to 5-(diethoxymethyl)-1,1,3,3,6-pentamethyl-1,3-disilaindane (14). In-situ aqueous acidification yielded 11. Conversion to 2 was then achieved via a Baeyer–Villiger oxidation followed by hydrolysis under basic condition. This novel methodology is useful, not only for the rapid, large-scale synthesis of 2, but also for the synthesis and development of new sila-substituted drugs derived from 11.

http://dx.doi.org/10.1016/j.tet.2010.07.068

Enantioselective alkynylation of aldehydes and ketones was accomplished using trimethoxysilylalkynes as alkynylating reagents and lithium 3,3′-diphenylbinaphtholate as a catalyst. Optically active propargylic alcohols were obtained in good to high chemical yields and enantioselectivities. Alkynylation of acetylpyridines afforded biologically active pyridyl propargylic alcohols in good enantioselectivities.

http://dx.doi.org/10.1016/j.tet.2010.07.080

The synthesis of chiral, nonracemic butadienylcarbinols by employing intermediate (trimethylsilyl)methylallenic alcohols is described. Allenic alcohols are obtained by treatment of aldehydes with (4-bromobut-2-ynyl)trimethylsilane in the presence of a catalytic amount of CrCl₃ or CrCl₂. Several new tridentate bis(oxazolinyl)carbazole ligands were synthesized and evaluated as the source of chirality. The synthesis of chiral allenic alcohols can be achieved in good yields (58–88%) and enantioselectivities (55–78% ee). Allenic alcohols may be treated with TBAF or 2 M HCl to provide the desired dienes in 43–86% yields. Alternatively, the (trimethylsilyl)methyl allenic alcohols afford iodobutadienyl carbinols when treated with N-iodosuccinimide.

http://dx.doi.org/10.1016/j.tet.2010.07.065

Mi Ri Kim, Seungwoo Lee, Jung-Ki Park, Kuk Young Cho
(Communication from Chem. Commun.)
Mi Ri Kim, Chem. Commun., 2010, DOI: 10.1039/c0cc01738h
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Shuchen Hsieh, Chiung-wen Hsieh
(Communication from Chem. Commun.)
Shuchen Hsieh, Chem. Commun., 2010, DOI: 10.1039/c0cc00164c
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Andreas Stahl Madsen, T. Santhosh Kumar, Jesper Wengel
(Paper from Org. Biomol. Chem.)
Andreas Stahl Madsen, Org. Biomol. Chem., 2010, DOI: 10.1039/c0ob00346h
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Kazuhito Tanabe, Eiji Matsumoto, Takeo Ito, Sei-ichi Nishimoto
(Paper from Org. Biomol. Chem.)
Kazuhito Tanabe, Org. Biomol. Chem., 2010, DOI: 10.1039/c0ob00275e
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Goncalo J. L. Bernardes, Raghavendra Kikkeri, Maha Maglinao, Paola Laurino, Mayeul Collot, Sung You Hong, Bernd Lepenies, Peter H. Seeberger
(Paper from Org. Biomol. Chem.)
Goncalo J. L. Bernardes, Org. Biomol. Chem., 2010, DOI: 10.1039/c0ob00372g
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Dan Zhao, Daqiang Yuan, Rajamani Krishna, Jasper M. van Baten, Hong-Cai Zhou
(Communication from Chem. Commun.)
Dan Zhao, Chem. Commun., 2010, DOI: 10.1039/c0cc02771e
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Giovanni Palmisano, Elisa Garcia-Lopez, Giuseppe Marci, Vittorio Loddo, Sedat Yurdakal, Vincenzo Augugliaro, Leonardo Palmisano
(Feature Article from Chem. Commun.)
Giovanni Palmisano, Chem. Commun., 2010, DOI: 10.1039/c0cc02087g
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Varun Kumar, Pallepogu Raghavaiah, Shaikh M. Mobin, Vipin A. Nair
(Paper from Org. Biomol. Chem.)
Varun Kumar, Org. Biomol. Chem., 2010, DOI: 10.1039/c0ob00230e
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Journal of the American Chemical Society, Volume 132, Issue 35, Page 12226-12227, September 8, 2010.

Journal of the American Chemical Society, Volume 132, Issue 35, Page 12214-12215, September 2010.

Journal of the American Chemical Society, Volume 132, Issue 35, Page 12365-12377, September 2010.

Journal of the American Chemical Society, Volume 132, Issue 35, Page 12246-12248, September 2010.