Carbonyl Olefination Research Articles

Garner's aldehyde as a versatile intermediate in the synthesis of enantiopure natural products.

Since its introduction to the synthetic community in 1984, Garner’s aldehyde has gained substantial attention as a chiral intermediate for the synthesis of numerous amino alcohol derivatives. This review presents some of the most successful carbon chain elongation reactions, namely carbonyl alkylations and olefinations. The literature is reviewed with particular attention on understanding how to avoid the deleterious epimerization of the existing stereocenter in Garner’s aldehyde.

Synthetic Routes toward Asymmetrically Substituted (Functionalized) 4H-Cyclopenta[2,1-b:3,4-b′]dithiophenes

A two-step synthetic protocol involving (i) a Wittig-type carbonyl olefination, and (ii) regioselective alkylation of the exocyclic double bond with LiAlH₄ and an alkyl bromide, was developed as an alternative to the recently reported three-step synthetic approach toward asymmetrically substituted/functionalized 4<i>H</i>-cyclopenta[2,1-<i>b</i>:3,4-<i>b</i>′]dithiophenes. The two routes are rather complementary, with specific advantages depending on the desired substitution pattern, and are of particular appeal for the construction of semiconducting materials to be applied in organic photovoltaics.

Organocatalyzed Carbonyl-Olefin Metathesis

The heat is on: A new [3+2] cycloaddition/cycloreversion strategy allows for catalytic and thermally allowed carbonyl-olefin metathesis (see scheme). This strategy opens opportunities for new developments in the field of carbonyl-olefin metathesis, which traditionally relied on stoichiometric amounts of transition-metal reagents or photochemical promotion.

Highly regioselective palladium-catalysed oxidative allylic C–H carbonylation of alkenes

Pd-catalysed direct oxidative carbonylation of allylic C-H bonds with carbon monoxide was first described. This new procedure shows that the inherent requirement for a leaving group in the Tsuji-Trost palladium-catalysed allylic carbonylation can be lifted, which provides a new route for accessing more synthetically useful β-enoic acid esters with high regioselectivity.

Conversions between metal–ligand multiple bond (MLMB) types: carbonyl olefination and other applications

In this Perspective, methods for the direct conversion of one type of metal-ligand multiple bond (MLMB) to another are discussed. Of particular interest, because of their potential utility in organic synthesis, are examples of direct conversion of N- and O-based MLMB to alkylidenes and alkylidynes. Recent efforts in this area from our laboratory with some background are detailed. The research from our group involves metallacycles prepared directly from an imido ligand where a metal-carbon bond can have alkylidene-like or alkyl-like properties and reactivity depending on the ancillary ligands.

Carbonylation of styrenes catalyzed by bioxazoline Pd(ii) complexes: mechanism of enantioselectivity

Preliminary studies of the elementary steps involved in the reaction of a chiral methyl carbonyl bioxazoline Pd(II) complex with aromatic olefins and CO have allowed development of a new enantioselective catalytic carbonylation process, leading to γ-ketoester derivatives with high yield and good enantiomeric excess. The intermediate palladacycle complexes have been isolated and characterized by NMR spectroscopy and X-ray diffraction. Factors that govern the stereoselectivity of the olefin carbonylation process are discussed.

ChemInform Abstract: Methods for Vinyl Ether Synthesis

AbstractReview: ca. 100 refs.

ChemInform Abstract: Carbonyl Olefination with α-Stannyl Ester Enolates: A New Synthesis of α,β-Unsaturated Esters.

ChemInform Abstract: Carbonyl Olefination with α-Stannyl Ester Enolates: A New Synthesis of α,β-Unsaturated Esters.

ChemInform Abstract: Reductive Carbonylation of Alkenes Using Zwitterionic Rhodium Complexes as Catalysts.

Alkenes react with carbon monoxide, sodium borohydride, propan-2-ol and a catalytic amount of Rh(cod)(η6-PhBPh3)(cod = cyclooctadiene) to give alcohols in fine yields; high regioselectivity for the branched or linear alcohol is usually observed, depending on the organic substrate.

ChemInform Abstract: Titanium-Mediated Carbonyl Olefinations. Part 2. Benzylidenations of Carbonyl Compounds with Dibenzyltitanocene.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Methods for Vinyl Ether Synthesis

Deceptively simple as the structure may appear, there is no singlegeneral method by which to synthesize the vinyl (enol) ether functionality.However, there exists a diverse array of complementary methods bywhich this functionality has been achieved. This review presentsthe scope and limitations of these methods according to reactiontype, specifically via ether modifications, elimination reactions,carbonyl olefinations, alcohol additions and carbon-oxygencoupling reactions. 1 Introduction 2 Modification of Ethers 2.1 Vinyl Ether Substrates 2.2 Allyl Ether Substrates 2.3 Acetylenic Ether Substrates 3 Elimination Reactions 3.1 Halide and Pseudohalide Leaving Groups 3.2 Alkoxide and Silyloxide Leaving Groups 3.3 Selenium Oxidation-Elimination 4 Olefination of Carbonyl Substrates 4.1 Phosphorus Reagents 4.2 Silicon Reagents 4.3 Sulfur Reagents 4.4 Metal Carbene Reagents 5 Addition of Alcohols 5.1 Alkyne Substrates 5.2 Dicarbonyl Substrates 6 Carbon-Oxygen Coupling Reactions 6.1 Palladium-Mediated Reactions 6.2 Copper-Mediated Reactions 7 Conclusion

ChemInform Abstract: Palladium(I) Carbonyl Cation Catalyzed Carbonylation of Olefins and Alcohols in Concentrated Sulfuric Acid.

A new palladium catalyst was found to exhibit high catalytic activity for carbonylation of olefins and alcohols. cyclo-Bis(μ-carbonyl)dipalladium(I) cation (1) with bridging CO ligands is formed by reductive carbonylation of palladium sulfate, PdSO4, in concentrated H2SO4. When an olefin or alcohol is added, complex 1 changes to a new complex (2) with terminal CO ligands, and tertiary carboxylic acids are obtained in high yields at room temperature and atmospheric pressure of CO. IR and 13C NMR studies suggest that complex 2 may be tentatively formulated to be [Pd2(CO)2]2+, in which the terminal CO ligands are chemically equivalent. Complex 1 is a catalyst precursor, and complex 2 functions as an active species for the carbonylation of olefins and alcohols. The catalytic behavior of the palladium carbonyl catalyst supports the recently proposed reaction mechanism involving an olefin−metal−CO complex as an intermediate for the catalytic carbonylation of olefins and alcohols in strongly acidic solution.

ChemInform Abstract: Novel Palladium(II) Complex Containing a Chelating Anionic N-O Ligand: Efficient Carbonylation Catalyst.

A novel palladium(II) complex containing chelating anionic pyridine-2-carboxylato and labile tosylato ligands is a highly efficient catalyst for the carbonylation of organic alcohols and olefins to carboxylic acids/esters. Carbonylation of primary, secondary, and tertiary alcohols as well as linear and functionalized terminal olefins was studied. In all cases remarkable activity and selectivity were observed. The catalyst is stable under reaction conditions even in the absence of excess phosphine ligands.

ChemInform Abstract: A New Rhodium Catalyst: Formation of [Rh(CO)4]+ in Concentrated Sulfuric Acid and Its Application to Carbonylation of Olefins.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Catalytic carbonylation in ionic liquids

Synthesis gas, which is formed upon the gasification of solid fossil fuels, is a source of carbon monoxide—a valuable reagent for chemical industry. In this review, studies performed in the last few years at the Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, on the catalytic carbonylation of olefins, alcohols, and halides in ionic liquids are considered. Catalytic systems containing no phosphine ligands were developed; these systems make it possible to recycle the homogeneous catalyst by the extraction of synthetic products from the reaction mass.

Silver‐Catalyzed Aldehyde Olefination Using Siloxyalkynes

We describe the development of a silver-catalyzed carbonyl olefination employing electron rich siloxy alkynes. This process constitutes an efficient synthesis of trisubstituted unsaturated esters, and represents an alternative to the widely utilized Horner-Wadsworth-Emmons reaction. Excellent diastereoselectivities are observed for a range of aldehydes using either 1-siloxy-1-propyne or 1-siloxy-1-hexyne. This mild catalytic process also enables chemoselective olefination of aldehydes in the presence of either ester or ketone functionality. Furthermore, since no by-products are generated, this catalytic process is perfectly suited for development of sequential reactions that can be carried out in a single flask.

Stereoselective Synthesis of Trisubstituted (E,E)-1,3-Dienes by the Site-Selective Reductive Cross-Coupling of Internal Alkynes with Terminal Alkynes: A Fragment Coupling Reaction for Natural Product Synthesis

A highly selective convergent coupling reaction is described between alkynes for the synthesis of stereodefined trisubstituted (E,E)-1,3-dienes-structural motifs commonly found embedded in the skeletons of bioactive polyketide-derived natural products. While numerous multistep processes for the synthesis of this stereodefined functional group exist, the current method represents a significant advance as it does not require stereodefined olefinic coupling partners (vinyl halide or vinyl organometallic); it proceeds by a single convergent C-C bond-forming event (avoiding multistep methods based on carbonyl olefination) and is tolerant of a diverse array of functional groups including free hydroxyls. Through a systematic study of titanium-mediated reductive cross-coupling reactions of internal alkynes with terminal alkynes, a fragment coupling reaction of great utility in natural product synthesis has emerged. Here, use of a proximal hydroxy group to control regioselection in the functionalization of a preformed titanacyclopropene has led to the establishment of a highly selective bimolecular coupling process, where C-C bond formation occurs in concert with the establishment of two stereodefined alkenes. Compared to the body of literature known for related metal-mediated coupling reactions, the current work defines a powerful advance, achieving site-selective bimolecular C-C bond formation without the need for using TMS-alkynes or conjugated alkynes. Overall, complex 1,3-dienes relevant for the synthesis of polyketide-derived natural products of varying stereochemistry were prepared with typically >or=20:1 selectivity, defining the important role of an alkoxide directing group located delta to preformed titanacyclopropenes.

Highly stereoselective and efficient synthesis of ω-heterofunctional di- and trienoic esters for Horner–Wadsworth–Emmons reaction via alkyne hydrozirconation and Pd-catalyzed alkenylation

In situ OH metalation with i Bu 2AlH and hydrozirconation with HZrCp 2Cl of HOCH 2C CH, ( E)-HOCH 2CH CHC CH, and HOCH 2C CCH 3 followed by Pd-catalyzed alkenyl–alkenyl coupling with ( E)-BrCH CHCO 2Et and ( E)-BrCH C(Me)CO 2Et using PEPPSI-IPr ( 7) as a catalyst provides a highly efficient and selective (⩾98% all- E) route to ω-hydroxy di- and trienoic acid esters ( 1a– 6a). The corresponding phosphonate esters ( 1c– 4c) of ⩾98% isomeric purity can be obtained via conventional bromination–phosphonation in >80% yields. As expected, their carbonyl olefination is ca. 85–90% E-selective with alkyl aldehydes but ⩾98% E-selective with PhCHO and some α,β-unsaturated aldehydes under the conditions used.

Concise Synthesis of P-Glycosyl Alkenylphosphonates and P,C-di and P,P,C tri-Glycosyl Phosphonates

A direct access to P-glycosyl-, P, P-di-glycosyl alkenylphosphonates and P, C-glycosyl phosphonates is described. The method involves the Horner reaction of an anion derived from P-monoglycosyl and P 1, P′-diglycosyl methylenediphosphonates either on the exocyclic aldehyde group of carbohydrates or on the masked aldehydic form of the furanose hemiacetals. In this last case, the carbonyl olefination, followed by an intramolecular cyclization, leads to P,C-di and P,P,C-triglycosyl phosphonates.

ChemInform Abstract: Recent Advances in Efficient and Selective Synthesis of Di‐, Tri‐, and Tetrasubstituted Alkenes via Pd‐Catalyzed Alkenylation—Carbonyl Olefination Synergy

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 of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.