A direct route to angularly substituted hydrindanes. Formal synthesis of bakkenolide-A and synthesis of an advanced intermediate to umbellactal

A direct route for the synthesis of highly functionalized angularly substituted hydrindanes has been developed. The key step involves RO-RCM of an appropriately functionalized norbornene derivative. The hydrindane derivative obtained in this way has been used to accomplish a formal synthesis of bakkenolide-A. This protocol has also been extended for the synthesis of an advanced intermediate to the synthesis of the diterpene umbellactal.     

Total synthesis of cytotoxic sponge alkaloids hachijodines F and G

The total synthesis of two cytotoxic sponge alkaloids hachijodines F and G has been achieved. The synthesis of both compounds utilises a common intermediate alkyne. By comparison of spectra the structure of the natural product has been confirmed.     

Straightforward synthesis and crystal structures of the 3-piperazine-bisbenzoxaboroles and their boronic acid analogs

The straightforward synthesis of a highly biologically active 3-piperazine-bisbenzoxaborole and its fluorine analog has been described. The obtained bisbenzoxaboroles have been used in the synthesis of their phenylboronic acids analogs. One diboronic acid has been also isolated as hydrochloride salt as well as its methyl monoester. All the described compounds display unique molecular architectures, which have been determined by X-ray measurements.     

Kinetics and mechanism of diphenylamine synthesis by the condensation of aniline with oxygen-containing compounds

The condensation of aniline and cyclohexanol (cyclohexanone) yielding intermediates and the subsequent dehydrogenation of these intermediates into diphenylamine have been studied. The mechanism of diphenylamine synthesis is substantiated. The kinetics of diphenylamine synthesis from aniline and cyclohexanol over a NiSnMg catalyst has been studied. A kinetic model in terms of the conversion of strongly chemisorbed species has been developed. The rate constants of diphenylamine synthesis at 260–300°C have been determined, which are consistent with the observed regularities. The kinetic model can be used in the determination of optimal synthetic conditions and in the design of a reactor for diphenylamine synthesis from aniline and cyclohexanol. Conditions have been found under which diphenylamine synthesis occurs at a high rate of up to 1 kg/(1h), with high selectivity, and with a high yield of up to 95%.     

Asymmetric synthesis and absolute configuration of streptophenazine G

The asymmetric synthesis of the antibacterial natural product, streptophenazine G, has been achieved by employing asymmetric alkylation and asymmetric aldol reactions using chiral oxazolidinones as the key steps. The originally proposed structure for streptophenazine G has been revised, and its absolute configuration has been determined to be 1'S,2'R,6'S. The asymmetric total synthesis of 6'-epi-streptophenazine G is also described.     

Enantioselective synthesis and absolute configuration assignment of gabosine O. Synthesis of (+)- and (-)-gabosine N and (+)- and (-)-epigabosines N and O

[reaction: see text] A rational approach to the synthesis of gabosines and other related carba-sugars starting from a masked p-benzoquinone has been designed. The enantioselective acetylation of the hydroxyketal 2 provides a practical entry to either enantiomer of the target products. The strategy has been applied to the synthesis of (+)- and (-)-gabosines N and O and (+)- and (-)-epigabosines N and O. The absolute configuration of natural gabosine O has been established.     

Application of catalytic dynamic resolution of N-Boc-2-lithiopiperidine to the asymmetric synthesis of 2-aryl and 2-vinyl piperidines

The highly enantioselective synthesis of 2-aryl- and 2-vinyl-piperidines has been accomplished through a catalytic dynamic resolution (CDR) of N-Boc-2-lithiopiperidine. The method has been applied to the synthesis of both enantiomers of the tobacco alkaloid anabasine.     

Synthesis of polyhydroxycyclohexanes and relatives from (-)-quinic acid

An efficient and versatile strategy for the synthesis of polyhydroxycyclohexanes and related compounds 3-6 is reported. The successful synthesis of these analogues has been achieved from a common intermediate, quinic acid derived lactone 2, rapidly accessible from cheap and commercially available (-)-quinic acid (1) as a chiral template. A practical route involving stereocontrolled epoxide formation and hydrolysis has been developed for the synthesis of 2,3-trans analogues 3 and 4. The preparation of the 2,3-cis analogues 5 and 6 has been realized by diasteroselective oxidation of a 5,6-double bond.     

Highly efficient diastereoselective biocatalytic acylation of a diastereotopic furanose diol and synthesis of key intermediates for amino derivatized bicyclonucleosides

The selectivity of Candida antarctica lipase has been demonstrated and employed in the manipulation of a diastereotopic furanose diol as the key step in the synthesis of a novel bicyclo 3-amino-3-deoxy furanose derivative, which is an important intermediate for the synthesis of bicyclic analogs of AZT. The asymmetrization of the diol has been achieved with preferred formation of a monoacylated product with 100% diastereoselectivity. An efficient synthesis of an intermediate in the synthesis of amino derivatized bicyclonucleosides is also described, two such novel compounds containing cycloamino residues have been prepared.     

An efficient strategy for the synthesis of endocyclic enol ethers and its application to the synthesis of spiroacetals

An efficient strategy for the synthesis of endocyclic enol ethers based on a Suzuki-Miyaura coupling/ring-closing metathesis sequence has been developed. The strategy has successfully been applied to the synthesis of spiroacetals, including cytotoxic marine metabolites attenols A and B.     

Direct conversion of methylarenes into dithiocarbamates,thioamides and benzyl esters

A new strategy for the synthesis of a variety of dithiocarbamates and thioamides has been developed employing inexpensive and readily available methylarenes under metal-free and solvent-free conditions. The approach offers a one-pot procedure and has also been extended to the synthesis of a diverse range of benzyl esters.     

Direct asymmetric Mannich reaction of phthalides: facile access to chiral substituted isoquinolines and isoquinolinones

The first Mannich reaction employing phthalides using a quinidine-based multifunctional catalyst has been developed. The reported method led to the synthesis of 3,3-disubstituted phthalide derivatives in excellent yields, with good diastereo- and enantioselectivities. Convenient synthesis of chiral isoquinolinones and isoquinolines has also been demonstrated.     

Enantioselective total synthesis of convolutamydines B and E

[reaction: see text] The first enantioselective total synthesis of convolutamydines B and E has been achieved using our vinylogous Mukaiyama aldol reaction. The synthesis features highly diastereoselective vinylogous Mukaiyama aldol reaction with isatin instead of aldehydes to construct a chiral center of convolutamydines. Additionally, the absolute configuration of natural convolutamydine B has been determined as R by its CD spectrum.     

Synthesis and absolute configuration of three natural ent-halimanolides with biological activity

The first three natural ent-halimanolides known until now have been synthesized from ent-halimic acid. Their structure have been confirmed as well as their absolute configurations established. Bestmann methodology has been used for the synthesis of butenolides and for the γ-hydroxybutenolides synthesis the Boukouvalas method has been employed. Biological testing has been carried out on these compounds.     

Total synthesis of (-)-tetrazomine. Determination of the stereochemistry of tetrazomine and the synthesis and biological activity of tetrazomine analogues

The first total synthesis of the potent antitumor antibiotic (-)-tetrazomine has been accomplished. A new method for the formation of the allylic amine precursor to an azomethine ylide has been developed and exploited in an efficient [1,3]-dipolar cycloaddition to afford the key tetracyclic intermediate used in the synthesis of (-)-tetrazomine. Several analogues of tetrazomine have been synthesized and tested for antimicrobial and biochemical activity.     

A clean and expedient synthesis of spirooxindoles in aqueous media catalyzed over nanocrystalline MgO

An efficient and eco-friendly method for the synthesis of spirooxindoles with fused tetrahydrochromenes has been demonstrated using basic nanocrystalline MgO catalyst in aqueous condition. The method has been applied for the synthesis of a range of compounds with variable functionalities in excellent yield and selectivity.     

分级结构纳米氧化铝的可控合成及应用

分级结构纳米氧化铝由于具有微-纳米尺度的协同和偶合效应近年来受到广泛关注。本文将不同形态的分级结构分为空心球状结构、核壳结构、簇状结构和阵列结构4种一般类型,并综述了其合成进展。简要评述了合成过程中的影响因素及分级结构形成的机理,并概述了其热稳定性的相关研究,还列举了其在光学与催化等领域的应用。最后,从分级结构的形态和性质的可控合成与实际应用相结合的角度展望了未来的研究方向。     

Asymmetric syntheses of heliannuols B and D

The synthesis of heliannuol D along with the first synthesis of heliannuol B has been achieved using Mitsunobu reaction and ring-closing metathesis as the key steps.     

Clean and efficient synthesis of O-silylcarbamates and ureas in supercritical carbon dioxide

The synthesis of a family of O-silylcarbamates from the corresponding silylamines has been achieved simply by heating the silylamine in supercritical carbon dioxide (scCO2), and these O-silylcarbamates have been shown to be effective precursors for the synthesis of a range of symmetrical and unsymmetrical ureas.     

Synthesis of ellipticine: a radical cascade protocol to aryl- and heteroaryl-annulated[b]carbazoles

[reaction: see text] Imidoyl selanides, synthesized from amides, have been used as radical precursors of imidoyl radicals in cascade reactions. The novel radical cascade has been developed for the simple synthesis of the medicinally important aryl-annulated[b]carbazoles. The protocol has been exemplified with the high-yielding total synthesis of the anticancer alkaloid ellipticine.