A variety of metalated tosylhydrazone salts derived from benzaldehyde have been prepared and were reacted with in the presence tetrahydrothiophene (THT) (20 mol %) Rh(2)(OAc)(4) (1 to give stilbene oxide. Of lithium, sodium, potassium tested, sodium salt was found highest yield selectivity. This study extended a wide aromatic, heteroaromatic, aliphatic, alpha,beta-unsaturated, acetylenic aldehydes ketones. On whole, high yields epoxides moderate very diastereoselectivities observed. broad...

The reactions of a range amide-stabilized sulfur ylides derived from readily available camphor-derived sulfonium salts for the synthesis glycidic amides have been studied. Primary, secondary, and tertiary were tested, it was found that highest enantioselectivities observed with amides, which provided in good to excellent yields, exclusive trans selectivity, enantioselectivities. reaction general aromatic aldehydes, but aliphatic aldehydes gave more variable epoxy could be converted cleanly...

The reaction of an amide-stabilized sulfonium ylide bearing chiral groups on sulfur has been investigated. We have discovered that the camphor-derived reacts with aldehydes at −50 °C in ethanol to give glycidic amides one step up 99% ee and complete diastereoselectivity. From analyzing reactions different ratios diastereomers it was found major diastereomer gave very high enantioselectivity, while minor much lower selectivity (54% ee). Further mechanistic studies revealed enantioselectivity...

Sulfur ylide methodology has been used to construct the Taxol side chain with a high degree of enantioselectivity via trans-aziridine followed by stereospecific rearrangement trans-benzoylaziridine into trans-oxazoline.

A straightforward synthetic route towards DAB-1 scaffolded dimeric iminosugars is described here, starting from readily available bis-glycosylamines. The method allows the integration of a variety linkages (aryl, alkyl, polyethyleneglycol chains) between both through choice bis-amine used in first step. Moreover, an additional substituent (allyl, ethynyl) may be inserted into structure via nucleophilic addition organometallic reagent to bis-glycosylamine. symmetrical ethynyl-iminosugar...

The synthesis of 2- and 6-substituted-3-aminopiperidines from Weinreb amides containing an allylamino fragment is reported. Involving the simultaneous hydrozirconation C═C C═O bonds, cyclization was promoted by BF3-mediated generation iminium. Proven to be highly diastereoselective, sequence can applied diversely substituted unsaturated valorized through preparation bicyclic heterocycles.

A simple synthesis of enantiomerically pure piperidine esters is described, offering a straightforward access to the trans-2,3-disubstituted skeleton which present in broad range biologically active compounds.

Access to nonracemic amino ketones via a hydrozirconation/transmetalation/acylation sequence applied Boc-protected 1-aminobut-3-enes is presented. This method was the stereoselective synthesis of cyclic imines (or iminiums) which were diastereoselectively converted into 2-cis-substituted and 2,6-cis-disubstituted piperidines. The potential this approach in field alkaloid illustrated by (−)-coniine (−)-indolizidine 209D. Furthermore, access indolizidines bearing quaternary center could also...

[structure: see text] Two diastereoisomeric P,N-ligands, (S,S)-1 and (R,S)-1, were synthesized assessed in palladium-catalyzed allylic alkylations. With rac-1,3-diphenylpropenyl acetate as substrate, ligand (S,S)-1, with "pseudo-C(2)" symmetry, exhibited higher reactivity enantioselectivity than the "pseudo-meso" whereas reversal selectivity observed rac-3-cyclohexenyl acetate.

A highly diastereoselective synthesis of trans-2-substituted cyclopentylamines via a tandem hydrozirconation/Lewis acid-mediated cyclization sequence applied to butenyl oxazolidines is described. The method allows an easy preparation diversely substituted which appear be useful synthetic intermediates. This was further illustrated by the syntheses (±)-Rodocaine, (±)-trans-pentacin, and enantiomerically enriched trans-cyclopentane-1,2-diamine.

Abstract A straightforward access to enantiomerically pure 2,3‐disubstituted pyrrolidines is reported that involves diastereoselective allylation of ( R )‐phenylglycinol‐derived imines and a sequential hydrozirconation–cyclization. number pyrrolidine derivatives bearing aryl, heteroaryl, alkyl alkenyl groups have been prepared in this way. Such compounds are useful building blocks the synthesis molecules biological interest, as illustrated by syntheses proline naturally occurring alkaloid...

Abstract Heavy metal on Lewis acid : The combination of lanthanide metals and AlCl 3 has been employed for selective single C−F activation in benzofulvenes comprising an exocyclic CF substituent. Intermediate ϵ,ϵ‐difluorinated metal‐dienyl species react with a large variety aldehydes highly regio‐ diastereoselective fashion to afford 1,1‐disubstituted indenes bearing difluorovinyl group. These new building blocks have further transformed through hydrogenation–cyclization process into...

The use of unprotected carbohydrate-derived nitrones as partners in strain-promoted alkyne-nitrone cycloadditions was investigated a new tool for bioconjugation. observed second-order reactions displayed rate constants 3.4 × 10-4-5.8 10-2 M-1 s-1, which is the common order magnitude reaction kinetics with other simple aliphatic or aromatic nitrones. Applicability this method to aqueous media demonstrated by performing one-pot protocol, combines sequential formation nitrone and cycloaddition...

A new diastereoselective synthesis of pyrrolidines from readily available chiral N-allyl oxazolidines is presented. The construction the pyrrolidine ring achieved via a tandem hydrozirconation−stereoselective Lewis acid mediated cyclization sequence.

Systematic exploration of zirconocene (Cp2ZrII) chemistry since the 1980s has offered a wide range useful methods for organic synthesis. Many these reactions are stoichiometric in zirconium, and even if several catalytic known, development is continuing interest. In this paper, study i.e. alkyne dimerization cyclotrimerization, presented. These carried out by employing recently introduced lanthanide-originated equivalent. The use 10 mol % Cp2ZrCl2, together with La metal or mischmetall as...

An asymmetric variant of the hydrozirconation reaction has been established starting from Boc-protected chiral allylic amines. The resulting diastereoselectively formed N-functionalized organozirconiums can be considered as promising chirons. In this case, they have transformed into enantiomerically enriched cis-2,3-disubstituted azetidines through a iodination/cyclization sequence.

Abstract The described titanium‐catalyzed hydroalumination of conjugated dienes opens up a new way to allylaluminium reagents. reaction is carried out by using diisobutylaluminium hydride (DIBAL‐H) and catalytic amount [Cp 2 TiCl ] (Cp=cyclopentadienyl). When applied mono‐ disubstitued pentafulvenes, this proceeds in highly endocyclic manner. formed compounds react regio‐ stereoselectively with both aldehydes ketones afford homoallylic alcohols that are suitable synthons for functionalized...

A spectacular inversion of α- to γ-regioselectivity in the allylzincation imines can be achieved by fine-tuning N-side chain. This approach allows easy preparation regioisomeric amines, racemic as well enantiopure forms. The usefulness method is illustrated parallel asymmetric syntheses 2,3- and 2,5-diphenylpyrrolidines.

The synthesis of unprecedented branched pyrrolizidines and indolizidines was accomplished <italic>via</italic> nitrone chemistry.

A "Cp2Zr" equivalent is generated under mild conditions (THF, room temperature) by reducing Cp2ZrCl2 with cheap and readily available mischmetall (an alloy of Ce, La, Nd, Pr). Coupling reactions, including those terminal alkynes, can efficiently be achieved using this reagent.