Synthesis Of Tetrasubstituted Alkenes Research Articles

Synthesis of Tetrasubstituted Alkenes by Rhodium-Catalyzed Regioselective Cyano Transfer.

We describe herein a novel, general, and robust approach to structurally diversified alkenyl nitriles through a Rh-catalyzed cyano transfer reaction between alkynyl-malononitrile derivatives and aryl/alkenyl boronic acids. This reaction exhibits high chemo- and regioselectivity and a broad substrate scope. The tetrasubstituted alkenyl dinitriles (34 examples, average 58% yield) are obtained through substrate tuning and ligand control.

Unlocking Diverse π-Bond Enrichment Frameworks by the Synthesis and Conversion of Boronated Phenyldiethynylethylenes.

The π-bond enrichment frameworks not only serve as a crucial building block in organic synthesis but also assume a pivotal role in the fields of materials science, biomedicine, photochemistry, and other related disciplines owing to their distinctive structural characteristics. The incorporation of various substituents into the C═C double bonds of tetrasubstituted alkenes is currently a highly significant research area. However, the synthesis of tetrasubstituted alkenes with diverse substituents on double bonds poses a significant challenge in achieving stereoselectivity. Here, we reported an efficient and convergent route of Cu-catalyzed borylalkynylation of both symmetrical and unsymmetrical 1,3-diynes, B2pin2, and acetylene bromide to the construction of boronated phenyldiethynylethylene (BPDEE) derivatives with excellent chemo-, stereo-, and regioselectivities. BPDEE derivatives could transform into novel tetrasubstituted organic π-conjugated gem-diphenyldiethynylethylene (DPDEE), vinylphenyldiethynylethylene (VPDEE), and phenyltriethynylethylene (PTEE) derivatives by a stepwise process, which provides a flexible platform for the synthesis of complex π-bond enrichment frameworks that were difficult to synthesize by previous methods. The initial optical characterization revealed that the synthesized molecules exhibited aggregation-induced emission (AIE) properties, which further establishes the groundwork for future applications and enriches and advances the field of functional π-conjugated frameworks research.

Synthesis of tetra-substituted olefins by NiH-catalyzed hydroacylation of allenes

In this issue of Chem Catalysis, Cho and co-workers invent an innovative way to easily synthesize all-carbon tetra-substituted olefins through a regio- and stereoselective hydroacylation of both 1,1-disubstituted symmetric and unsymmetrical allenes with various anhydrides. This PˆN ligand-ligated NiH system reveals a complementary regioselectivity to Cu catalysis.

Photoredox-catalyzed halotrifluoromethylations of alkynes with triethylammonium halides: synthesis of tetrasubstituted alkenes containing CF3 and halogens

The introduction of F- and CF3-groups into alkynes is enabled by photocatalysis under mild conditions. The developed method can be extended to providing chloro- and bromotrifluoromethylated alkynes and bioactive compounds functionalization.

Origin of the E/Z Selectivity in the Synthesis of Tetrasubstituted Olefins by Wittig Reaction of α-Fluorophosphonium Ylides: An Explanation for the Low Stereoselectivity Observed in Reactions of α-Alkoxy Aldehydes.

A series of tetrasubstituted fluoroalkenes were synthesized in good yield and high E/Z selectivity (up to 96/4) by Wittig reaction between α-heterosubstituted ketones and α-fluorophosphonium ylides. A detailed study of factors that control stereoselectivity in these reactions shows that stereoselectivity is the result of stabilizing CH···F and N···C═O interactions in the addition TS leading to the E isomer. This analysis provides a rationale for the observed decrease in selectivity for reactions of stabilized ylides with α-alkoxy aldehydes.

Synthesis of tetra-substituted olefins via annulation by Pd-catalyzed carbopalladation/C–H activation and solid state fluorescence properties

Palladium-catalyzed and norbornene-mediated multiple C–C bond forming strategies to highly substituted helical olefin incorporated 1,2,3,4-tetrahydroisoquinolines have been developed via double carbopalladation/C–H activation of 2-bromo-N-benzylpropargylamines. The scope of the above carbocyclization process has been studied by varying the substitution on starting materials which have been synthesized using A3-coupling (mine–ldehyde–lkyne). Interestingly, the synthesized compounds show a pronounced solid state fluorescence property due to their restriction of intramolecular rotation in the condensed phase.

ChemInform Abstract: Synthesis of Tetrasubstituted Olefins by Palladium‐Catalyzed Double Heck Cyclization of Bromoenynes.

ChemInform Abstract: Synthesis of Tetrasubstituted Olefins by Palladium‐Catalyzed Double Heck Cyclization of Bromoenynes.

ChemInform Abstract: Haloboration of Internal Alkynes with Boronium and Borenium Cations as a Route to Tetrasubstituted Alkenes.

Vinyl boronates are extremely useful precursors, especially for the formation of new C–C bonds by cross-coupling and conjugate addition reactions.1, 2 Although alkyne hydroboration is a powerful synthetic route,3, 4 it is not applicable to the synthesis of trisubstituted vinyl boronates. Thus, alternative regio- and stereospecific methods are needed, particularly for subsequent use in the formation of tetrasubstituted alkenes,5–7 as the production of these important biologically active compounds as single isomers by classical methods is challenging.8 One simple approach to trisubstituted vinyl boronates is the functionalization of internal alkynes by metal-catalyzed 1,2-carboboration9–13 and 1,1-carboboration.14 The introduction of two selectively transformable moieties onto an internal alkyne should enable ready access to tetrasubstituted alkenes by successive cross-coupling reactions. Significant progress has been made in this area, particularly in the dimetalation of internal alkynes to provide two nucleophilic sites of distinct reactivity.15–19 The haloboration of internal alkynes is an attractive alternative to dimetalation, as it generates ambivalent synthetic intermediates that contain both a nucleophilic and an electrophilic position.20 These synthetic intermediates are ideally suited for the diversity-oriented synthesis of tetrasubstituted alkenes. To date, the application of alkyne haloboration with boron trihalides (BX3) has been limited to terminal alkynes, and has proved an effective route to produce trisubstituted alkenes with excellent regio- and stereoselectivity.21–25 The haloboration of internal alkynes is unsuccessful with BCl3, and it is either slow25 or produces isomeric mixtures susceptible to B–C bond cleavage when BBr3 is used.21, 26 Recent calculations found that the haloboration of internal alkynes with BCl3 is endothermic, but as the Lewis acidity of BX3 increases (Cl<Br<I), haloboration becomes exothermic, and the energy of the key transition state is also reduced.27 This result suggested that an increase in the electrophilicity at boron beyond that of BX3 would facilitate the haloboration of internal alkynes.

ChemInform Abstract: Synthesis of Tetrasubstituted Alkenes by Stereo‐ and Regioselective Stannyllithiation of Diarylacetylenes.

AbstractThe selectivity of the reaction is controlled by subtle steric and electronic effects.

Synthesis of Tetrasubstituted Olefins by Stereoselective Allylzincation-Negishi Tandem Reaction of Acetylenic Sulfones

Tetrasubstituted olefins containing a 1,3,6-triene structural unit can be regio- and stereoselectively synthesised in good yields under mild conditions in one pot, by allylzincation-Negishi tandem reaction of acetylenic sulfones with allylzinc bromide and alkenyl halides.

Highly Stereoselective One‐Pot Synthesis of Tetrasubstituted Alkenes via Carbopalladation Reaction of Fluorine‐Containing Acetylene Derivatives.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Synthesis of Tetrasubstituted Olefins by Pd‐Catalyzed Addition of Arylboronic Acids to Internal Alkynes.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis of Tetrasubstituted Olefins by Pd-Catalyzed Addition of Arylboronic Acids to Internal Alkynes

[Reaction: see text] Tetrasubstituted olefins are readily prepared by the Pd-catalyzed cis addition of two aryl groups from an arylboronic acid to opposite ends of the triple bond of internal alkynes. The synthesis proceeds under very mild reaction conditions and tolerates a wide variety of functional groups, including alcohol, aldehyde, ester, TMS, and acetal groups.

Development of new synthetic method and function of ynolate anions

Ynolates are carbanions having a triple bond in place of the double bond in enolate anions. Ynolates are ketene anion equivalents, thus ynolates introduce a ketene unit into substrates and the resulting products possess high reactivity. This allows ynolates to undergo unique reaction sequences. For the past 20 years, several methods for the generation of ynolates and their reactions have been developed. Recently, we have developed a novel efficient method for their generation via cleavage of ester dianions. Starting from this success, we have found new reactions of ynolate anions. Ynolate anions react with carbonyl compounds to give beta-lactone enolates, which are converted into olefins with high E-selectivity. It is noteworthy that high E-selectivity was achieved in the synthesis of tetrasubstituted olefins. Utilizing the strong nucleophilicity of the beta-lactone enolates, we have succeeded in the first tandem [2 + 2] cycloaddition-Dieckmann condensation to lead synthetically useful 2,3-disubstituted-2-cycloalkenones in good yields. Ynolate anions were found to react with N-sulfonyl aldimines to give beta-lactams. N-2-methoxyphenyl aldimines efficiently activate their cycloaddition of lithium ynolates via chelation to give beta-lactams and alpha,beta-unsaturated amides. We have demonstrated the high functionality of ynolate anions. Ynolate chemistry has begun and much remains to be discovered.

Nickel-catalyzed addition of Grignard reagents to silylacetylenes. Synthesis of tetrasubstituted alkenes

Nickel-catalyzed addition of Grignard reagents to silylacetylenes. Synthesis of tetrasubstituted alkenes

The synthesis of alkenes from carbonyl compounds and carbanions α to silicon. IX: stereoselective synthesis of tetrasubstituted alkenes.

The synthesis of alkenes from carbonyl compounds and carbanions α to silicon. IX: stereoselective synthesis of tetrasubstituted alkenes.